Building 3D models with Digital Photographs

A guide to Small-Craft Monitoring, Preservation, and Documentation


Author: Kyle Hunter, The Center for Wooden Boats
Contributors: Jonathan Taggart, Jack Becker, David Cockey, Kathrine Cockey, Todd Croteau, Dana Lockett, Don Rothwell, Eric Hervol, Nat Howe

Cover Photo 1.JPG


Project Background

The Center for Wooden Boats, funded by the Institute of Museum and Library Service and in part by 4Culture, led a year-long experiment to develop a new method for using digital photogrammetry for long term monitoring of the condition of large objects. The team found that the photogrammetry software and method tested throughout this project is not only capable monitoring the changes in shape of an object over time, but is powerful enough to use for a variety of different applications. CWB and the project partners unanimously agree that digital photography used with Agisoft Photoscan Software (Photogrammetry) is a tool comparable to other technology available on the market (like stationary laser scanning and total station survey), yet it is economically accessible to smaller institutions with limited available resources.

As small museums are often limited by funding opportunities for documenting objects, this process of building 3D models from a series of digital photographs avails institutions with a low-cost solution to what has previously been difficult for smaller institutions to afford. Over the course of a few months, CWB staff, consultants, and volunteers began to collect data to test the process of Agisoft Photoscan and how it could be applied to common scenarios that small museums or historical institutions would be likely to encounter. These methods can be applied to creating 3D models for the purpose of comparing the change over time or design of two objects, either different or similar, comparing changes in shape of an object over time, creating lines drawings of small craft, and documenting scaled complex objects not easily measured by hand.

The purpose of this document is to provide an overview of the concepts and methods used in this study along with some ways of using the created 3D models. It is not intended and a step by step tutorial. Others may choose to use other software which will have its own strengths and limitations. Some specifics have been included regarding the software that was used where we discovered peculiarities and learned important lessons.

Documentation vs. Interpretation

When a historically or culturally significant boat cannot be maintained or preserved, the standard practice is to document it by creating lines and construction drawings that might allow someone to reproduce the boat. With Photogrammetry, the photographs taken are the primary document of the current state of the vessel or object. In the future, researchers can return to these documents for information, and to create better 3D models than we are able to today. The photos themselves need to be preserved and not altered. Everything after the photographic stage that documents the object as-is is an interpretation. The 3D models that we create, though highly accurate are an interpretation. In the process of turning these models into drawings, many compromises, idealizations and judgments are made. The quality of these may be subtle or substantial depending on the skill of the interpreter.

Explanation of Photogrammetry

Photogrammetry is the science of using photographs to make measurements of a real world object or scene. This usually results in a drawing, map, or 3D model.

A 3D model is a representation of an object using a collection of points plotted on a grid with an x, y, and z coordinate system. Though there are many ways to create 3D models of an object, this research project primarily focused on building 3D models using an inexpensive software program called Agisoft Photoscan, as it has been found to be the most accessible method available to smaller institutions. (It should be noted that the project used the Standard edition, Educational software which is substantially more cost effective than the commercial and the professional versions of the software.)

You begin by taking multiple, overlapping digital photos of your object. For a 20 foot object, you might have 200-400 photos as an example. An eight foot distance is a good rule of thumb, though there are many cases where this isn’t possible. The software works by aligning common points in multiple photos and plotting those points on an x, y, and z axis in 3D space. The quality of the model will depend largely on the quality of the photos, and it is highly recommended that sufficient time is spent on taking a good set of photographs. For the same object mentioned above, about three hours were spent photographing.

Just as there are various techniques to getting good photos, the same goes for processing the models. First, one must know to what end your model will be used. If you are running quick comparisons on objects, you can process the 3D model on low settings thereby significantly speeding up the process. If the model is to be used for documenting measurements, it should be processed at a higher setting. Second, Photoscan has a variety of tools to help process models. Eliminating background “noise” can be accomplished with a masking tool, a snipping tool can be used to manually erase extraneous points, and photos can be processed in smaller sets to create individual “chunks” which can be merged later to create the complete model.

Required Equipment

To build a model using Photoscan, you will need the software, a digital camera and accessories, and a computer capable of processing large amounts of data.

The following comprises a list of the equipment used by CWB to achieve the majority of the results reported.
  • Dell Laptop- $1250
    • Processor: Intel® Core™ i7-4500 CPU @ 1.80GHz
    • Installed memory (RAM): 16.0 GB
    • System type: 64-bit Operating System, x64-based processor
    • Agisoft Photoscan standard edition (educational version) $65
    • Canon Camera- $650
      • PowerShot G12
      • Travel Tripod with 360 degree ball mount- $65
      • Floor tripod to allow for perpendicular camera angle to the object from the ground- homemade with ball mount- $20
      • Remote shutter release - $35
      • Painter’s Pole with camera mount- $30 (for tall objects)
      • Blue tape- $5
      • Tape measure- $10

Building a 3D model of a Mukilteo boat in Agisoft Photoscan, and other general tips

As a rare relic from the 1940’s recreational fishing industry in the Puget Sound region of Washington State, this Mukilteo boat does not have any supporting historical documentation in the form of original plans, design, or construction drawings. Because there are so few of these boats in existence due to very limited production by the builders, it is important to document the shape and construction details in order to preserve the maritime heritage of this region. In particular, this 3D model was created to derive the lines plans and construction drawings.

For more information on this boat or the plans produced, please refer to the HAER WA-224 with the National Park Service Historic Records Division.

Object Setup

The Mukilteo boat was setup with 360 degree access supported by four sawhorses, providing as much access as possible underneath and above the object. Depending on the object, it is not always possible to have complete access. In fact, no matter the object, there will always be some areas obscured by supports unless specialized efforts are applied. Concerning all of the 3D models outlined in this document, this does not present a huge issue. As long as these supports are minimal and one can photograph around them, the essence of the shape should be captured.

This Mukilteo boat was stabilized by adding strategically placed wedges in as few places as possible. This allowed the camera the maximum access to the hull by minimizing visual obstructions.


One should always include a highly visible measurement of some type. This could be a premeasured distance between two pieces of tape or features, or an actual tape measure that has been extended and numbers are legible. The scale should be included in a few photos, but it is not necessary to include in every photo, but it should be in as many as possible. It is important to make sure that the tape measure, if used, be included in the 3D model as it is developed. When providing a measured length, provide the longest practical measurement, as the longer the measurement, the more accurate the model will be. In the photo of the Mukilteo boat below, the yellow arrows point the inside edges of two pieces of blue tape, of which is 15 feet. The green arrow points to the written measurement also present in the photograph.

It is also recommend to take measurements (and photos of those measurements) of the object, so that they can be factored into the model at a later date. For example, one can take a specific measurement from the tip of the stem to the tip of the stern. While these photos may not be useful for the model construction, they will always remain as notation included with the photo documentation. That way they can’t easily be lost as they could be written on a piece of paper. One can then manually pick out specific points in the model and set the scale based off of those specific measurements.

Note: that the scale cannot be added to the 3D model in the standard edition of Agisoft Photoscan, though that feature is available in the professional version. Instead, the project team is used Rhino 3D for that purpose, which will be discussed in more detail in that section.

Sample of scaled photos including a tape measure below.



Note: The 3D model will be only as complete as the photo sets that are taken. Take the time for proper set up and quality photographs.

The lighting in the warehouse was overhead fluorescent, suspended about thirty feet above the object. On average, half of the fixtures were functional. A Canon G12 camera on variable settings, both automatic and manual, was used to capture the photos. The photos were taken in an orderly and consistent way, to make them easier to keep track of while processing. To capture the hull, roughly 30 photos were taken clockwise around the boat at eye level, keeping a consistent height locked on the tripod and a roughly consistent distance from the object regulated only by sight. The next set was raised a couple of feet to get a slight downward angle, and shot clockwise in a similar fashion.


To get the bottom of the hull, which was especially dark as it was not lit well, a manual setting with an open aperture and slow shutter speed allowed the photos to show the details of the surface. If a photo is too dark, the details cannot be “read” by the program. The camera was affixed to a self-built wooden contraption (floor mount) to which an adjustable ball joint camera mount was fastened. This allowed the camera to be locked into a position so that the lens was facing up toward the bottom of the boat (and ceiling). With a remote control shutter release, the contraption was pushed along snapping over-lapping photos, back and forth under the boat until the entire bottom was captured.


Tips for photography for use in Agisoft Photoscan
  • Photos should be taken anywhere from 4’ to 8’ ft. away from the object, depending on the size. As the object increases in size, generally so should your distance. However, a closer range will produce more detailed results
  • Best results occur from photos taken in even, diffused light
  • Shiny, smooth, and uniform surfaces are difficult for the program to read
  • A tripod, floor mount, and remote shutter release are very helpful for creating good photographs
  • It takes time to get quality photos. If you are ever in doubt, take more. You may never have access to the object again. The setup might be time consuming, but once done the photos are free. It is much more time consuming to return to setup and create more photos.
  • 2/3 overlap of the object from one photograph to the next is necessary, ¾ overlap is better
  • Turn the histogram setting on, and use it. This will help reading the exposure for good photographs.
  • Keep lens parallel to the face of your object.
  • A bright light, sun, or sky will be challenging to work with. If you are shooting in the direction of the light, this will silhouette your object and the software will not be able to read the details of the photograph. You have to either carefully shoot only your object (and no background) to avoid the light, erect a background to block the light, or wait until conditions change.
  • Changing aperture, shutter speed, or automatic to manual settings will not affect the results of the model.
  • Make sure you have ample storage for digital photographs and charged, spare batteries.
  • Avoid moving light sources which relocate shadows and can potentially confuse the program.
  • Extra, more overlapped photos may be needed when photographing the transition around the corners of the object to ensure that the program can make the transition from one surface to the other.
  • Extra photos need to be taken in obscure interior areas such as inside the bow or transom or under thwarts to insure that these areas are captured. Ensure that you create a “path of photos” that the software can “stitch” together.
  • If you keep your set up intake until after you have processed you can see if there are areas where additional photographs are needed to fill holes or other areas with more data.

Using Agisoft Photoscan Software

Agisoft Photoscan offers the standard edition to educational institutions for $65, or to unaffiliated individuals for $200. The demo version can be obtained at no cost but doesn’t allow the saving of projects.

The following workflow describes how the Mukilteo boat model was generated, and offers general notes and tips. If new to Agisoft Photoscan, this should be read in conjunction with the software tutorial and Help file available through the software developer.*

The “workflow” tab in the Agisoft Photoscan interface contains all the actions to build a model.

Add Photos> Align Photos> Build Dense Cloud> Build Mesh> Build Texture>

Add Photos>
558 photos of the Mukilteo boat were initially added to the “chunk” which becomes “chunk 1”. This is a good time to inspect photos and make sure that there are no blurry, dark, or duplicate photos that aren’t useful to the process. Photos can be either removed or disabled, the latter of which will keep the photo in the loaded file by essentially turn it off.

Align Photos>
Of the 558 photos that the software attempted to align, about 140 were not. 60 of those comprised of the dark bottom of the Mukilteo boat, and 80 were shots of the interior. Two other chunks were created, one for each section that didn’t align. Within each of the chunks, the photos were re-aligned.

In the workflow tab, there is also the option to align and merge chunks. As the photos were now separated into three chunks, or three separate sections of the boat, they needed to be aligned. Selecting align chunks and merge chunks will combine all the data.

  • Bounding Box- this is an adjustable tool that is useful to cut down on unnecessary processing. The program will only process what is inside the box, so make certain that while adjusting the box around the object it is looked at from multiple views.

  • Cutting/cropping- This tool is useful to clean up “noise,” or unimportant points that are picked up on a floor, wall, or ceiling around the object. Or in the case of the Mukilteo boat, the sawhorses were also cut out. It can be used in conjunction with the bounding box, for example cleaning up points around the object that are still within the bounding box.

  • Camera positions- This tool will turn the camera positions on and off for each photo. These are the blue rectangles in the previous photos. This is a useful tool to ensure that the cameras are aligned properly. Sometimes the software will align the photo, yet the blue rectangle will be “way off in space” or backward.

Build Dense Cloud>
After all the photos were properly aligned, a sparse cloud of data points we present on the screen. This isn’t a highly detailed point cloud, but will indicate any “hole” in data, perhaps where more photos are needed or where photos didn’t align properly.

Build Mesh>
The mesh is the tool that creates polygons from the points, or lines that connects adjacent data points to one another. The program is extrapolating the information that is created between the points of the cloud. When creating mesh, Agisoft meshes all of the points first, then the number of connections is reduced (in a process called decimation) down to the number selected. Un-decimated files are large and contain more detail, though they can be cumbersome to use in software programs, creating “choppy” interfaces, lagging speeds, and program crashes.

Build Texture>
The texture tool adds the color information from the photographs to the surfaces created on top of each polygon. This gives the cosmetic detail to the model that will most closely resemble the object.

This 3D model was decimated to reduce its file size to about 3-4MB before it was exported into Rhino3D. Decimating the model will allow for better performance and minimize slow speeds and program crashes

*Note: Software tutorials for Agisoft Photoscan can be found at www.agisoft.com. It is recommended that beginners follow the procedures outlined in the tutorial, though initially skipping the masking process. The workflow process is thoroughly detailed in the help file of Agisoft Photoscan and goes into much great detail than below.

Combining photos from different sets

Twilight is a NW built 36’ fishing trawler built in Seattle in 1933 by Harold Hansen. A once common double ender of the era, she was acquired by Northwest Seaport, a partner organization for this grant, in 2000. In December of 2013, while floating in the water, the team comprised of project partners listed in this grant took a complete set of digital photographs from various vantage points around the vessel. Twilight was moved repeatedly throughout the photo shoot, and photographs were taken from other floating boats and from the pier. A tripod was not used for all shots.

The resulting model generated in Photoscan was remarkable. Two other common ways of capturing enough data for generating a 3D model, stationary LiDAR (laser scanning) and Total Station survey, are not capable of generating a model of an object in motion. Note that because the boat was in the water, the model lacks any information below the waterline.
Later, in July of 2014, Twilight was hauled out and trucked up to Pt. Townsend, WA for storage out of the water. Nat Howe, present for the original photo shoot, took another set of photos after she was blocked up. The model that we created of this latter shoot was “merged” in Photoscan with the model from the former, resulting in a model of the boat in its entirety. NW Seaport has a base model of Twilight to monitor her dimensional stability by comparing it to later models built from future photo shoots.
  • Observations:
    • Photos can be added and processed at a later date to make a more complete model
    • Photoscan works on objects in motion, whereas laser scanning and total station will not
    • Photoscan works on large objects

Using 3D models

3D models can be useful in a variety of ways. One can use a model to create detailed lines plans and construction drawings in Rhino3D, AutoCAD and other design programs to help preserve the cultural information of the boat, and record enough information to build replicas. A 3D model can be used to create a cultural object study that deftly illustrates the cultural information in a more easily interpretable way, such as in a museum panel. The data information that make up these models can be compared to one another using Cloud Compare, showing differences in the change of the shape of an object over time. This same program is even capable of comparing objects of very similar design by aligning the points with one another. The following case studies are presented to illustrate the capabilities of the different software programs and what is needed to accomplish similar tasks.

Creating lines plans in Rhino and AutoCAD


Rhino3Dis a versatile 3D modeling program capable of constructing, processing, and animating 3D models. The educational copy of the full version runs approximately $200, while the version for the unaffiliated individual costs $1000. Rhino3D allows the user to accurately scale the 3D model to match the actual object, and then to section the model to obtain the various waterlines, station lines, and buttock lines. However, as powerful as Rhino3D is as a modeling tool, it lacks some capabilities in creating finished technical drawings. Once the relevant lines are defined on the model, they can be projected to a single reference plane and exported as a 2D AutoCAD file. AutoCAD (approx. $500) is arguably the industry standard drafting and design program for technical drawings, although any good drafting program can be used. Regardless of which program is used, following conventional drafting practices will ensure clearly understood drawings.

Significant knowledge of both of these software programs is required to get accurate and professional results, as these programs are more complicated than Agisoft Photoscan. Likewise, strong knowledge of boat construction and lofting plans is required at this stage.

Note: It has been observed the file names that contain spaces Photoscan can be problematic when exporting the photographic texture files (renders) to Rhino3D.


The 3D model is imported into Rhino3D as an .obj file. (All spaces should be left out of the file name i.e. mukilteoboat2013.obj).

The first step after importing the model into Rhino (or any other program) is to align it as precisely as possible to the XYZ axes, meaning level fore-and-aft and level athwart ships.

Locating Station 0 and Baseline intersection at the Origin would also be a good suggestion, but is not critical. Typically the stem is used as the vertical reference, and the load waterline as the longitudinal (horizontal) reference.

Note: As these objects are not perfectly symmetrical, and construction is not always square and fair, it is at this stage that lines plans become interpretations of the actual object. If any artistic liberties or judgments are made in this interpretation, it is valuable to make note of that in any final reports.

It is in Rhino3D that the traditional lines of the boat are added, and the model in divided by those lines into the sections that will represent the boat in the drawings. The green lines are Station Lines, red lines are Waterlines, and the blue lines are Buttock lines. It is worth noting that proper orientation of the model is critical before creating these lines. The model should be level and plumb as much as possible. The sawhorses and blocking are integral to the boat. Removing them at this stage would leave “holes” in the model. Additional masking of the photos in Agisoft Photoscan prior to creating the model may have reduced or eliminated some of these unwanted components. Supports and stabilization methods should be kept as minimal as possible to increase the view of the surface of the object, but small discrepancies such as these are relatively easy to correct in Rhino3D.

Refining the lines in Rhino

The lines follow the surface of the model, including the sawhorses. Agisoft Photoscan can produce reasonable lines of complex curves, yet edges and corners are generally not as distinct. However, higher quality models usually have better representations of corners and edges.

Additional editing can be performed in Rhino3D to provide missing data, such as plotting the theoretical points along the edge of the transom. This gives the user the ability to correct for inaccuracies created by Agisoft Photoscan, as its tendency to round off sharp edges or to distort certain geometries can make it difficult to automatically extract crisp lines. This is also the case with the edge of the deck and the rub rail, which may have two relatively sharp edges in close proximity and also obscures the true sheer line. An example of this “fairing” technique is shown below. The software user extrapolated the edge of the transom using the Red lines.

The screenshot above represents the port side of the transom. Note the roughness of the waterlines from the model. The smooth lines represent a faired interpolation of those lines, which were then extended to define their intersection points. The series of points derived in this manner define the theoretical edge of the transom and are included in the Table of Offsets on the Lines Drawing. (For scale reference, the actual distance between waterlines is 3”, so the roughness of the lines and the margin of error appears quite small over most of the model.

Similarly, the diagram above is an example of how the sheer and rabbet points can be derived at each station section. The surfaces of the hull and deck are very consistent until approaching the deck edge, which is severely distorted due to the presence of a rub rail. Drawing faired lines through the “good” portions and then extending them to their logical intersection produces the desired point on the Sheer line. In the case of the rabbet, the faired line of the hull is simply extended to the half-breadth plane of the keel.

Table of Offsets

Smooth lines are drawn in Rhino through the coordinate points at each station to create a 3D wire frame image of the hull.
These are the points that ultimately become the Table of Offsets. The offsets were obtained from the model by the coordinates of each point in the Body Plan. Automated routines are available, however the user did not use that in this case. The traditional Table of Offset notation is in feet-inches-eighths-+ format; though it is not one that any automated routine can accommodate.


As good as Rhino is for 3D modeling, it isn’t so good for 2D drawing preparation, so these lines were exported into AutoCAD.

The Lines Drawing documents the size and shape of the hull, such that a new hull can be built to the same shape if desired. In actual practice, when building a boat, the Lines are drawn, or Lofted, full size in order to correct small errors in the offsets and to provide full size patterns for molds, transom, stem, and certain other components.

The Construction Drawing documents the parts and pieces of the boat and how they are assembled. The Photoscan model is superimposed on the drawing to aid in locating the various components of the hull (frames, engine stringers, thwarts, etc.), but the model is not accurate enough in itself. Manual measurements or scaled photos of each component are necessary for an extremely accurate drawing.

Direct tracings of oddly shaped individual components like the one below can also be scanned and traced in AutoCAD.

  • Observations:
    • Agisoft Photoscan is an excellent tool for capturing an accurate scale of 3D shapes of objects, within an 1/8 of an inch over 20 feet
    • Agisoft Photoscan does not capture edges well
    • The basic version of Photoscan can’t be used alone for the purposes of documentation- additional software is necessary (Rhino3D and AutoCAD)
    • It is not possible to accurately capture small features within the 3D model, i.e. a screw head or cross-frame in a boat
    • Many measurements for the detailed construction drawings must be made by hand and factored into Rhino3D

  • Equipment and cost:
    • AGISOFT Photoscan software $65 Educational copy
    • AutoCAD $400-900
    • Rhino3D $195 Educational copy
    • Window PC Laptop (recommended CPU) - $1500
    • 12 megapixel digital camera- $500
    • Tripod $90
    • 25-30 hours of labor

Creating a cultural object study in Rhino3D using orthographic projections

Note: This section contains terminology specific to Rhino3D, so a basic understanding of this program will be necessary in order to fully comprehend it.

While lines plans with table of offsets and detailed construction drawings are very helful for builders to take on a new construction project of an original classic, it isn’t always necessary to create them in order to preserve all of information. Many boats do have their original documentation, and of those that do, it might be more important to document the specific object for cultural purposes; i.e. the rowboat that took George Washington across the Delaware River vs. other boats built by the same builder of the boat that President Washington used. Creating a study such as this has potential to reach a wider audience using a more general interpretation in order to grasp the details of an object that can’t be touched or easily seen.

An orthographic projection is “projection of a single view of an object (i.e. a perpendicular view of the object) onto a drawing surface in which the lines of projection are perpendicular to the drawing surface” Merriam-Webster, M-W.com. This means that all perspective distortion has been eliminated from views such as the top, front and right side views. However, it does not apply to the rotated perspective views (see green arrow above).

The above montage is comprised of drawings and orthographic photos imposed over those drawings. This was created to show how the textured (rendered) orthographic projections of the scaled 3D model can be used in conjunction with lines drawings. One of the advantages of this type of presentation is the amount of cultural information included in one page of documentation. As the drawings for the Mukilteo boat in the previous study were created by the user’s judgment to record the lines in what makes sense in terms of construction, this can lead to a compromise in detail of the original object. There are often variations in the actual object to its original state, such as off center frame placement or repairs that have altered the object from its original construction, all of which might be erased when creating a lines plan and construction drawings. The variations that are evident in the Davis boat (above) is a good example of how this method of record can capture the object as-is, while still allowing the reader to use a divider and scale to garner qualitative measurements from it. Therefore, these textured orthographic projections are a more accurate form of documentation closer to the original object. Additionally paint colors and even the shadows of the boats numbers can be seen, which would be eliminated from drawings, though possibly noted in the report and definitely included in any accompanying photographs.

To create these views in a drawing, the textured 3D model has to be exported from Agisoft Photoscan in the .obj format. File names and chunk names can have no spaces in them. This export is a group of files and should be opened in Rhino3D as a group when given the option. The model then has to be scaled using a known measurement, its starting and ending points, and a scaling factor. The scaling factor has to be calculated. One can do this by drawing a line between the starting and ending points in the model and determine its length: this is the model length. Divide the known measurement by the model length. This will give you the scaling factor. Select the entire object in Rhino3D and scale it by the scaling factor to create the scaled model.

The model needs to be rotated around the three coordinate axes so that it is set up level and square. The model can now be contoured to create stations, water, and buttock lines. Locating the model appropriately on the World Coordinate Plane will allow the automatic generation of a table of offsets from the Rhino3D add-on program Orca 3D. The format of this table is not in the traditional form (as described in the previous study), and may need to be further manipulated in Excel.

Rhino3D has drafting functions that allow for the creations of Layouts like the one above with any number of Detail views appropriately layout scaled. Each Detail can be individually controlled to show the desired view with an individual set of layers showing.

The half drawing of the interior of the Davis boat was created by using a Clipping Plane centered on the keel of the boat. It was not possible to transfer it to the Detailed View in the Layout in the usual way. It was captured with the keyboard Print Screen command, then opened in Photoshop, cropped and saved as a jpeg. The jpeg image was then put in the Layout using the Picture Frame command and scaled. Information about its original scale seemed to be retained in the jpeg. Two things should be noted in this view. The first is the breakdown of quality in the model under the thwarts and in the bow and stern. In these areas there was not sufficient photographic data to produce a clean surface model. The second is the major holes in the model in the bow and stern. In these areas where there is complete failure of the surface model you can see through to the backsides of the far surface. The green line is to note the location of the clipping plane where it cuts through the surface model.

The Layouts chosen in the montage above and the level of detail entirely depends on the project goals determined beforehand. This study is meant as a primer to illustrate some possibilities of what can be accomplished using this technology.

Monitoring the change in shape of an object using Cloud Compare

Cloud Compare and software tutorials are available for download at no cost at www.danielgm.net

Large object collections are often stored in less than ideal conditions so it is incumbent on collection managers to monitor the condition of those objects carefully. This presents its own set of challenges. By the time a change in shape or size of a large object is perceptible by the eye, significant, irreversible damage has already occurred. To accelerate the process to get to a conclusion on whether these software programs were capable of recognizing the change in the shape of a hull, CWB used a derelict recreational fishing boat built in 1929 to physically manipulate that very change.

A 3D model was built using the same method explained with the Mukilteo boat above. To simulate the shape change that might occur over time, a lead weight was cantilevered out over the gunnels of the boat, in opposing directions, giving the hull a definite and perceptible twist. Then, mimicking elapsed time of a lengthy period, as might occur with an improperly supported boat, we created a second 3D model. We repeated the photographic process to minimize any possible errors arising from a change in camera settings or photographer, and built models using the same parameters in Photoscan.

Exporting the models from Agisoft Photoscan as a standard .ply file and uploading them each into Cloud Compare, we were able to align the models to the points most common to each model. Cloud Compare provides the user with a heat map type function to illustrate the differences in the shape of the 3D model, thereby highlighting the differences in our physical hulls. The red coloring illustrates the most extreme differences between the two models, while the areas without coloring represent sections of the boat unaffected by movement.

In order to qualify the actual distance of movement into relative units of measurement, the model needs to be scaled in Rhino3d prior to uploading into Cloud Compare. More overall research is needed to determine the level of accuracy using cloud compare, as the project was only able to test simulation of a shape change of one object. However, based on other studies in this project, the accuracy level is estimated to be roughly 1/8inch error over 20 feet.

If highly accurate measurements are needed before further research is conducted using the baselines of other models in this project, the total station survey is a proven method to measure that movement. The Vhasa Museum (http://www.vasamuseet.se/en/) has done an excellent job of geodetic measuring using total station survey that produces results with an accuracy of less than 1mm.

Based on this project alone, Cloud Compare is a very useful, inexpensive, and less technical of a process that will tell if// the object is changing rather than by how much. The great value of this process is to determine whether to take precautions to stabilize the object or turn to the geodetic measuring process using the total station to provide a more precise accuracy.

  • Cloud compare is an accessible “open source” program available free of charge
  • The program is quirky, yet it can provide quick results
  • The object must be scaled prior to use in Cloud Compare in order to qualify the actual change in shape
  • Large data files will cause the program to crash, so it might be necessary to decimate the 3D model
Equipment and cost:
  • AGISOFT Photoscan software $65 Educational copy
  • Cloud Compare Free Open source
  • Window PC Laptop (recommended CPU) - $1500
  • 12 megapixel digital camera- $500
  • Tripod $90
  • 6-8 hours of labor

Comparing design differences of the hulls of one-design sailboats using Cloud compare

The Center for Wooden Boats cares for a fleet of eight Blanchard Junior Knockabouts (BJK). These boats were built on Lake Union in Seattle, WA during 1933 and 1947 to give customers access to an affordable “daysailer” during the depression. The design was a shortened version of the Senior Knockabout, and the story goes that building the first few BJK’s too many planks were broken during construction due a strong curve at the bow of the boat. In order to prevent this from happening further, the design was elongated slightly to lessen the curve. Of the eight that CWB owns, one is the shorter version at 19’ LOA compared to 19’8”. While the length is easily distinguishable to the eye, the complex curvature in the shape of the bow is more abstract to comprehend and ultimately compare by hang measurement.

Building a model of each vessel in Photoscan, we exported them and uploaded them the same way we did the two models of the Reinell fishing boat. The white hull (top) is the shorter, earlier version and the stripped hull (below) is the latter, elongated version.

Cloud Compare aligns the majority of the points together automatically, creating a model that reveals the changes as layers are peeled away. In the photo below, the green hull represents the elongated version. Illustrated is the drastic “bump” as the models combine at the stem of the bow. Further towards the after section of the BJK the difference in the height of the boat is revealed. The elongated hull is narrow and sleek whereas the shorter hull is stubby and thick.

  • Layers of objects can be peeled away to reveal an section that could be of interest
  • Cloud Compare allows the user to pick up on differences immediately that would be more difficult and time consuming to measure by hand
Equipment and cost:
  • AGISOFT Photoscan software $65 Educational copy
  • Cloud Compare Free Open source
  • Window PC Laptop (recommended CPU) - $1500
  • 12 megapixel digital camera- $500
  • Tripod $90
  • 6-8 hours of labor

Comparing Photoscan to common methods

Photogrammetry is not a new science. However, methods continue to evolve. The results attained by Agisoft Photoscan are most similar to those attained from laser scanning, as both methods automatically generate high numbers of points that make up the dynamic surface of an object. Total station survey has been used in the past for boat documentation, yet it stands apart from these two methods because of its limited data capture overall.

Agisoft Photoscan
Stationary LiDAR (laser scanning)
Total Station survey
Digital Photographs
Equipment - type
High mega pixel (12+) Camera


Remote shutter release

Pole tether

Tae measure


Laptop for remote view (large or tall objects)

HDS terrestial system


High/low tripods

Camera (could be part of scanner)

Platform for large or tall objects

Total Station

Prism poles


Equipment costs for fieldwork and data processing
Camera - $200 - 2000, median $500

Tripod- $100

Remote shutter- $40

Painters pole (large and tall object) - $20

Misc. Camera- $100

Laptop- $1250

Agisoft Photoscan software- $65 EDU

Rhino3D Software- $195 EDU

AutoCAD- $400-900

CloudCompare- Free
Leica ScanStation C10 - $82,000.00

C10 yearly maintenance - $10,000.00

Extra Targets and equipment - $10,000.00

Pano-Camera and Equipment - $ 3,000.00

Leica Cyclone Register Software (1 Seat) - $7,000.00

Cyclone Register Subscription (1 Seat) - $1,200.00

Leica Cloudworx Software (1 Seat) - $4,000.00

Cloudworx Software Subscription (1 Seat) - $500.00

AutoCAD (1 Seat) - $5,000.00

AutoCAD Subscription (1 Seat) - $300.00

Shipping Cost (field work) - $300.00 - $1,000.00
Total Station- $6,000

Accessories- $500

Multisurf Software- $900
Total Estimated Costs
Portable- data can be retrieved on the fly using minimal equipment.

Lightweight, easy to transport.

Low-cost and accessible.

Can capture data on a moving object.

Can capture data in the dark using a camera flash.

Can work in tight areas if sufficient overlapping photos are taken with wide angle lens.

Works around obstructions such as columns or scaffolds without additional processing as long as sufficient, suitable photos are taken.

Works with very small to very large objects – small models to large vessels with accuracy relative to size of object.

Users can bank photographic data over time and process models at a future date.
Accurate- very capable of high level detail.

Proven- has been highly developed and vetted.

Works well with very large sites or objects
Dimensions and Geo-referencing are built into the data capture process.

Access to some areas that would otherwise be too distant (300meters).

Can capture data (Not Color) in total darkness.
Portable Equipment.

Highly accurate points mapped to X,Y,Z coordinate system.

Relatively simple to use.
Evolving and developing technology Capturing edges of an object can be difficult depending on experience level

Scaling is not built into the process and must be added and captured manually. This cannot be done in the standard edition of Photoscan
Can't capture color data in the dark unless lights are used.

Can't capture data on a moving object

Doesn't work well in close or tight areas.

Expensive hardware and software needed.

Requires multiple cases of gear- increased difficultly to logistics and transport.

In areas with many obstructions such as columns or scaffolds many station setups are required to capture the complete structure (each set up is time consuming and requires visibility to targets from the scanner).
Requires two people.

Cultural information and colors are not captured in the model.

One point is captured at a time, subject to where the team places the target.

No photographic images are attained.
Model only has as many points as are captured by the user.
One click of the shutter provides one point.

Comparing Agisoft Photoscan to Stationary LiDAR (laser scanning)

Honor Pole

CWB was gifted a 20’ Honor Pole to commemorate a dugout canoe carved by Haida Native Saaduuts, an Artist in Residence at The Center for Wooden Boats. Like any cultural object or artifact made of organic material and on display outdoors, it is subject to degradation by rain, UV light, and other environmental factors.
This model was built using the same photographic method as all of the other models. The technique however, differed slightly. As the pole is 20’ tall, we attached the camera to a mounting plate that sat atop a painter’s pole so that we could capture the surface at a perpendicular angle throughout the object. We used a camera cord to attach to a laptop, where we installed remote viewfinder software from the camera manufacturer. This allowed us to see and capture the object while remaining on the ground level.
As part of this project is the focus of using the software for the documentation of objects, we found Agisoft Photoscan to be a highly capable tool to aid in process. It is very difficult to measure such an abstract object as this by hand; having a scaled, 3D model can provide a variety of information that other methods like photography and sketching cannot.

In addition to the construction of a model using Agisoft Photoscan, this object was a good candidate for a direct comparison to the laser scanning method to test its viability. Cloud Compare, the same program used in the simulation to monitor dimensional stability, was used to compare the two methods of 3D model making.

Method 1: Stationary laser scanner (LiDAR)- Todd Croteau (NPS)
Data Capture:Leica ScanStation C10 - Todd Croteau (NPS)
Software: Leica Cyclone Register, Leica Cloudworx Software - Todd Croteau (NPS)
Equipment Cost (one time, including yearly maintenance and software subscriptions): $123,500

Method 2: Digital Camera and software- 2013-2014- Jonathan Taggert, Kyle Hunter, Eric Hervol
Data Capture: Digital photographs processed in AGISOFT Photoscan software- Kyle Hunter
Software: Agisoft Photoscan and Cloud Compare
Equipment Cost (one time): $3,500 (includes digital camera and laptop which can be used for multiple purposes)

This screen shot captures a comparison (middle) the between an Agisoft Photoscan point cloud (left) and a LiDAR point cloud (right). The pole depicted in the center is the comparison of clouds aligned using Cloud Compare software. The yellow, orange, and red coloring that you see represents minor discrepancies between the two models. The biggest differences are in the chin of the face of the figure holding the canoe and the canoe itself. The difference in the chin is due to the shadow of the chin in the photographs used to build the model in Agisoft Photoscan. The difference in the edges of the canoe that the figure is holding stems from the difficulty of the Agisoft Photoscan software to process edges in detail.

Note the “garbled” section at the top of the model built in Agisoft Photoscan. This is due to the silhouetting that occurred against the sky, darkening the object, and the failure of the software to align the photos properly. This is also reflected in the screen shot below, where many points are missing. This could be remedied by taking additional photos and adding them into the software and ultimately the model.

It is apparent that both technologies are capable of comparable results, as long as the Agisoft Photoscan process was thoroughly done. We would have better results in our Agisoft Photoscan model if more pictures were taken in areas that had pointed, thin edges or deep shadows.

Deciding which method might work better for this type of tall object would depend on the circumstances. Both models needed more information as you go further up the pole.

It is apparent that both technologies are capable of comparable results, as long as adequate photos are taken for building the 3D model.

  • Both technologies are capable of comparable results.
  • Laser Scanning provides a higher level of detail, yet has limitations of portability and cost.
  • Photoscan results improve as the photography work is detailed and the lightning favorable.
  • Areas of great shadow and a high contrast of light between object and background are examples of challenging environments that worked against the ability to produce a model of greater detail in this example.
  • Deciding which method might to use for this type of tall object would depend on the circumstances. If this pole were in a remote area, Photoscan would be a better option. If this pole were in a museum and one had access to laser scanning method and a lift to elevate the scanner.
  • Note there is also some missing information at the top of the pole that comes out as a jumble of graphic in this depiction. That is due to the program having a difficult time recognizing all the photos as the sky behind it was cloudy and bright. That missing information could be shot at a later point in order to make it more complete.
Equipment and cost:
  • AGISOFT Photoscan software $65 Educational copy
  • Cloud Compare Free Open source
  • Window PC Laptop (recommended CPU) - $1500
  • 12 megapixel digital camera- $500
  • Tripod $90
  • Painter’s pole $30
  • 6-8 hours of labor

Nordic Spirit

Nordic Spirit is a large, Viking-style ship built in Northern Norway approximately 200 years ago. It is currently owned by the Nordic Heritage Museum in Seattle, WA, and is on permanent display under a covered outdoor section in front of the museum. Because of the age of the vessel and the challenges of preserving it, it is prudent to make a good base model to monitor its stability.

Nordic Spirit was scanned using a stationary LiDAR laser scanner, an instrument capable of capturing immeasurable detail. In this case, the vessel was supported by several obstructions that left significant “holes” of information in the model. Due to the nature of the scanner and limitations in mobility, it is not possible for the scanner to read obscured areas.
A view of the main obstruction from the support system.

A model of the boat was also built in Agisoft Photoscan, using the same process outlined in previous studies of this document. While no technique is able to penetrate obstructed sections of the object, a camera is small enough to work around in the majority of tight spaces. A more complete model was created using this method. This model is a good base to compare future models to in order to monitor the stability. It also serves as an illustration of the versatility of the Photoscan method.

Comparison of Total Station to Photoscan- Salish Canoe

In 2008 4Culture gave The Center for Wooden Boats a grant to document two vessels owned by CWB. The vessel of this particular study is a unique 15’ 6” Salish Dugout Canoe. In 2009 Todd Croteau of the National Park Service HABS/HAER program came out to help CWB document this vessel, of which resulted in an Historic American Engineering Record (HAER) being filed with the Library of Congress.

In 2013, with continued support from 4Culture, CWB experimented with a new method of data capture using digital photoscanning. CWB was able to compare the results from a Total Station in 2009 with results from this new method of digital photoscanning, providing a unique opportunity to study the similarities and differences of each process.

Method 1: Total Station survey- 2009 by Todd Croteau (NPS)
Data Capture: Leica TCR303 Total Station- Todd Croteau (NPS)
Delineated: AeroHydro Multisurf 6.0 software- Todd Croteau (NPS)
Equipment Cost (one time): $14,000

Use of the total station requires two individuals and captures as many points as the user is willing to provide. One person controls the machine while another holds a reflective mirror target to be captured by the machine. Accuracy is dependent upon the eye to place the points in correct positions. That point cloud created in the totalstation is then downloaded into multisurf software, where an accurate lines plan can be produced.

Method 2: Digital Camera and software- 2013-2014- Don Rothwell and Jack Becker
Data Capture: Digital photographs processed in AGISOFT Photoscan software- Don Rothwell
Delineated: Rhino 3d software and AutoCAD software- Jack Becker
Equipment Cost (one time): $3,500 (includes digital camera and laptop which can be used for multiple purposes)

Training individuals with these methods can be tricky. As with any process, a new skillset might be required. In each case, there is hardware (total station vs. camera) and software unique to each process that must be mastered. The learning abilities of each individual will determine the speed and accuracy at which these methods can be used. They are similar in complexity and therefore cannot be argued that one method is easier to use than the other. It was gathered through experience and discussions that each method is comparable to labor spent on each result.

The “Photoscan Lines” below are as they came out of Rhino3D directly from the model. They were further interpreted by the author and “faired”, in order to provide the reader with smooth lines that better represent the actual object.999.JPG

Here the lines after the author “faired” them, as they were derived from the Agisoft Photoscan, Rhino 3D, and AutoCAD process. Those “faired” lines (red) are overlaid onto the lines derived from the Total Station process (black). The reader can see that they are close in proximity. It must also be noted that the 3D model built of the Salish canoe was one of the first done in the project, and therefore of a rather low quality. As the user learns the process, results are dramatically improved.

Here the lines derived from the Agisoft Photoscan, Rhino 3D, and AutoCAD process (in red) are overlaid onto the lines derived from the Total Station process.


  • Similar results were achieved using the two methods.
    • Digital photoscanning equipment is more accessible and cost-effective.
    • Digital photography is more common than total station survey, and therefore finding qualified people with a basic understanding of photography is easier.
    • Photographs for the process of photoscan can be obtained at any time, and archived for the future. Even if a model were to never be built, hundreds of detailed photos of the object would exist in case it was ever altered, destroyed, or lost.
    • If a small institution chooses to invest in Method 2, half of the cost is in the camera and computer necessary to capture and process the photos. These items might already be owned and can be used for multiple purposes, thereby potentially reducing the impact on the financial constraints of the organization.


Overall Conclusions- start taking photographs now

The intended result of this project was to develop a cost effective, simple method to monitor the condition of irregularly shaped large objects, in order to best preserve the cultural heritage specific to regions and peoples. Though the preservation of these objects is the ultimate goal, it is inherently impossible to prevent the deterioration and ultimate destruction of organic materials. Luckily, the methods studied go well beyond monitoring an objects stability and reach deep into the preservation of culture.

The methods of ways using the technology outlined here for the preservation of objects are infinite. There also exists other forms of software and tools to achieve similar results that are not even mentioned. That said, this study highlights some options for institutions of all sizes to begin or continue documenting large objects that are especially prone to more rapid deterioration.

The project partners unanimously agree that the collection of data is the single, most important thing that an institution with large objects can begin doing. By using a good quality digital camera and spending the time to gather a proper set of digital photographs, these pictures can be processed at any point in the future. An institution initially needs only to spend the resources to learn the photographic method and techniques compatible with Agisoft Photoscan in order to begin collecting data.

  1. An initial startup cost of $2400, including computer, camera, software, and accessories provides the necessary equipment and software to build 3D models as seen here.
  2. Monitoring an object requires approximately 8hrs for photographs and model construction.
  3. Documenting and object and creating lines drawings and construction details requires approximately 30-40hrs and necessary software for an additional $700.


  • Portable: data can be retrieved on the fly using minimal equipment and does not require fixed tripod locations
  • Photographs can be taken at any time, for future processing
  • Low-cost and accessible to institutions with smaller budgets
  • Can capture data on an object in motion
  • Can capture data in low light with camera flash
  • Can work in tight areas if sufficient overlapping photos are taken with wide angle lens
  • Works around obstructions such as columns or scaf­folds without additional processing as long as suffi­cient, suitable photos are taken
  • Works with very small to very large objects – small models to large vessels with accuracy relative to size of object

  • Evolving and developing technology- subject to change
  • Capturing sharp edges of an object can be difficult, depending on experience level
  • Scaling is not built into the process and must be added and captured manually. This cannot be done in the standard edition of Photoscan
  • Does not work well on smooth surfaces with no texture or graphic patterns (i.e. smooth/white fiberglass or freshly painted wood hulls with no plank seams)

Description of project partners

Nathaniel Howe: Naval Archaeologist. Nat provided insight into the challenges that vessels face over the period of their lifetime, experience in documenting and monitoring gained from graduate work, and provided the data collection for the study of the Twilight.

Jonathan Taggart: Drawing on experience as a professional conservator, Jonathan helped steer the project into meaningful and realistic goals. His valuable efforts included photography, analysis, and data collection.

Todd Croteau: As a project architect in the HABS/HAER program of the National Park Service, Todd brought years of documenting experience and validation to the methods we were testing.

Dana Lockett: As a project architect and technical expert on the HABS/HAER team, Dana recognized the value in the method for data collection that we attained, and helped to oversee that the research being done was thoughtful and complete.

David Cockey: David taught the team the Agisoft Photoscan method, complete from photography using the software. Using career experience as a design engineer, David guided the group to achieve goal-oriented results, provided excellent feedback and problem solving, and continued to consult throughout the entire project. David was in attendance at the Council of Maritime Museums conference, one venue where these findings were presented.

Kathrine Cockey: Katherine, an engineering manager, helped organize this project and guide its direction. She assisted with the teaching and generated a comparison of the various documentation techniques.

Eric Hervol: A computer programmer and professional boatbuilder, Eric’s expertise in both fields provided accurate insight into the relevancy and efficient uses of some of the software we tested.

Jack Becker: As a structural designer/draftsman, Jack excelled in the photographic data collection and the transformation of the 3D model in 2D lines plans. His work directly made possible the success of that process into a submission of another vessel in the HAER documentation program.

Don Rothwell: Don has spent a career in photography, art, murals, and instruction. Don helped with data collection and experimentation with model construction in the software.

Kyle Hunter: Collection Projects Manager at The Center for Wooden Boats, Kyle managed this project from the point the funding was awarded. He has participated in every phase of the project including planning, logistics, photography, model building, dissemination, financial management, and reporting.