Photogrammetry Blog Post 4: Conclusions

In conclusion, the project has been an overall success. However, there are some changes I would make if encountering this task again. The quality of images could have been improved by using different settings on the camera during capturing. I believe the brightness and focus could have been altered in certain images. The set up of the workplace including the lightbox meant that the light didn’t have to be changed the majority of the time. However, after my experience in Louth County Museum I would have focused more on these settings. I lacked the necessary attention to the detail during the capturing stage.
The experience within St Mary’s church proved to be more useful. As a result of the previous experience in the Archaeological Museum I ensured further attention to detail. Instead of the maximum 91 images I used during the pot model I had a larger collection of 215 images. I captured more images at more angles which allowed for greater precision using the Photoscan software.
The experience was a very worthwhile one which gave me great knowledge of working alongside a museum. If opportunities arose in the future to do further work using Photogrammetry in museums, I would be keen to be involved in the process. St Mary’s church has also been a brilliant experience. It is great to see the interest and happiness the extension of a historical monument can give to an institution.

Photogrammetry Blog Post 3: Software

The process of using Agisoft Photoscan proved to be a reasonably difficult feat. Overall, I have completed a total of six different models. All of which had problems and issues to overcome.
The general workflow, after downloading the pictures, will now be discussed. After capturing around one hundred photographs I opened each to critique if any editing was needed before importing into Photoscan. The photos in terms of brightness and shadows seemed to be fine, however a few photographs had problems with focus. A mistake I would not be able to correct post processing. An important lesson was learned at this point, to ensure that photos are in focus during the capturing stage. Although we had the remote control of the Canon using Shane’s laptop, I had not ensured continual quality in a small amount of the photos.
The post processing complete, which became a time for reflection rather than editing, I transferred the images into Photoscan. Another problem occurred as I could not use RAW images, only JPEG’s were importing to the software. At this stage I had confidence that the model would still remain photorealistic. The photos are now placed in the gridview below the main Photoscan panel, as seen below.
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The first time creating the model I focused on using the magic wand as a masking tool. Opening each image into the main window, a single click allowed the magic wand to remove any obscure parts of the image, in this case the white area surrounding the pot. The image below shows the area designated by the magic wand. Although it seems to cover most of the image problems still arose.
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A severe problem was found here in the form of an assumption. The assumption that the magic wand would suffice for the production of the model. It proved false, as I will show in an image below. The assumption wasted valuable time, the mesh cloud and points take time to complete. Further work in masking parts of the image had begun. Use was made of the rectangular selection tool and intelligent scissors. This allowed for a more precise look at the model. The image below illustrates the rectangular section in use.
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This tool proves useful when there are large chunks which need to be deleted from an image. However, when a more precise deletion is needed the intelligent scissors prove to be the best tool. This allows for a user to select points which map around the object, ensuring that the first and the last point match, as seen below.
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After all these steps had been completed, the workflow was completed. Finishing the dense cloud and mesh was part of this process. My laptop power only allowed for medium settings to be completed at this point. But, the outcome would not change hugely. Importantly, an error occurred at this point with missing parts of the bowl and essentially some floating sections found outside the main shape. Although the sections on the outside of the model could easily be deleted using the Photoscan cutting tool, it could not fix the missing pot sections.
I attempted to rectify this by finding the images which had not been completed correctly. A simple zoom out function allowed for this to be possible. However after many attempts I concluded that the images used was the main problem.
The texture selections found within Photoscan are interesting, allowing for greater detail and different viewings. However, the generic setting is perhaps the easiest to complete and looks suitable.
The final product of the archaeological pot was a disappoint with regard to the original thoughts of the project. The conclusion to be found here was to be more precise during the early stages of the project. Mistakes had been made with the capturing of the images which could not be improved at a later stage.

Pot
by nathanmurphymu
on Sketchfab

The use of Autodesk 123d Catch proved to be an easier process. The software only allows for 70 images to be used. These images were automatically uploaded and rendered using the software. The software does allow for a series of post processing once the model has been completed, these include squares and line selects. These allow for deletion and further processing. The mesh can be changed after the original one has been completed. The choices range from mobile, standard and maximum depending on the power of a computer. Video functions are also available with uploads to youtube and the possibility to save to desktop.It has to be said that the user interface of this software is a lot more accessible than Agisoft Photoscan. The primary screen is shown below.
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The result of the model can be seen below. Although the majority of the model can be seen and there are no holes present, like the first model there are still remaining problems. It shows that the inside of the pot was not captured properly, meaning there is a hole on the inside of the pot. Yet again the software used to complete photogrammetry has proven that mistakes were made during the capturing process which could not be rectified at a later date.

http://www.123dapp.com/catch/Capture_2015_04_20_02_13_24/3839554

Photogrammetry Blog Post 2: Photogrammetry Uses

The Bronze Age pots found in the Irish archaeology museum hold a very interesting history. The process of photogrammetry used for the capturing of my own Bronze Age pot was a method specific practice.
The bronze pot was placed within a lightbox. LED lights were placed at three points surrounding the item. Photogrammetry needs equal light on all parts of the object to ensure no shadows or shininess. The box was placed on a table ensuring that height became a problem for the practice. The larger LED light, which used a larger tripod, looked down from the top of the object. Chairs had to be used on either side of the lightbox to ensure the surrounding light. Balance becomes quite important here because the lights cannot move during the process of photogrammetry, otherwise the data will be corrupted because the common points cannot be found.
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The bronze pot was placed on a rotating table allowing for easy use of the Canon 60D on the tripod. Instead of moving around the object, like one would do with a larger object, the item could be spun using the table and photos then captured. The pot had to be turned each time, ever so slightly and the photo captured.
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Importantly, the curator at the museum had to flip the pot to its other side. This was to ensure that the inside and bottom of the pot was captured evenly to ensure a full model.
The inside of the pot would prove to be the most difficult to capture. As the pot was rotating and the angles of capturing had changed it became clearer that the inside of the pot was being captured correctly.

Photogrammetry Blog Post 1: Working in a Cultural Heritage Institution

The National Archaeology Museum was very accommodating of our work with the Bronze Age pots. We were given access to a large activity room for the photogrammetry and it proved to be very suitable. The curators ensured that we had all relevant information by providing books and short lectures. It was this surrounding information which helped the completion of the project as a whole. The 3D visualization in Cultural Heritage is a fast growing field. The adaption of cultural heritage institutions to these new digital techniques allows for greater visualizations of the past.
Working in cultural heritage institutions eludes to fountains of knowledge. Although a specialist topic was being completed in the museum. The extra information provided by the institution itself extends the knowledge of any person involved in the projects. The Bronze Age pots which were used during this project have a strong history. Originally found near Castlefinn, County Donegal, they are now found at the National Archaeological museum.The specific bowl used for myself was a simple bowl with an inverted rim. Comb impressions are found on the inside of the rim with a similar motif surrounding the outside of the bowl. The rest of the bowl is decorated with simple lines and triangles.
The experience gained while working with the museum will prove useful in future career paths. The completion of the MA in Digital Humanities opens up avenues of employment which cater greatly to cultural heritage. Inter and intra personal skills were improved. We also experienced important advancement of photography skills, including setting up a workspace and focusing clear capturing.
The fragile nature of the bronze pots meant that the only possible movement for the students was rotation using a turntable. When the bottom of the pot had to be captured a museum worker would help. The accommodating nature of the cultural heritage workers continued throughout the day with consistent support and frequent updates.