Week 1 Overview (June 29th, 2012)
Dale Kronkright scheduled Mark Mudge and Carla Schroer from Cultural Heritage Imaging to spend a week training staff on Computational Imaging. Cultural Heritage Imaging’s ambition is to make digital imaging methods more utilized to preserve and monitor cultural artifacts.
Mark and Carla trained us in two methods of Computational Imaging. The first being Reflectance Transformation Imaging (RTI) and the second Stereoscopic Photogrammetry. The first day was primarily explanation of theory and how the software processed the images.
Several days were spent training RTI and how to shoot ideal images. Our speed and placement of the flash progressed after each attempt. First we shot O’Keeffe’s painting “Untitled (Cottonwood Tree)” and “Horn and Feathers.” However, “Horn and Feathers” was also shot in infrared.
After processing the images in RTIBuilder, detailed texture the human eye cannot see was made clearly visible. “Soap bubble’s,” due to humidity changes, were also made clear. In the infrared RTI image Dale was able to point out the underdrawing of O’Keeffe’s painting.
Toward the end of the training we travelled to O’Keeffe’s home in Abiquiu where we did more Photogrammetry and RTI imaging.
Overall, week 1 turned out to be very successful. CHI prepared us to continue capturing images throughout these 8 weeks and we will continue to post updates on our progress.
Week 1 (June 29, 2012):
We completed our first week of intensive training on June 29th. The first day we learned the theory and technique behind two methods of Computational Imaging: Reflectance Transformation Imaging (RTI) and Photogrammetry. Being unfamiliar with the two methods it was easy to grasp the concept but difficult to grasp how it processed. The first few days we worked primarily with RTI and how to process the images in the software. Equipment for these methods are extensive so it will take several attempts to be familiarized with them and how to set up. When the equipment was being introduced to us I was slightly overwhelmed because I was unfamiliar with most of it; it became more clear after using it once or twice. In this case learning is by doing.
We ran into some initial issues when beginning RTI. The new Canon 5D camera had an issue and had trouble communicating with the computer. After several attempts we had to switch to Mark and Carla’s camera. It worked the following day without explanation so it was a minor hiccup. Our first RTI came out successful. Since we are mimicking a dome, we spent some time trying to get the flash to the correct position. As we continued practicing, visualizing each angle became easier and much quicker.
Since there is so much equipment and things to keep track of for RTI, minor hiccups can stall a shoot from a few minutes to several hours. Batteries not being fully charged or camera malfunctions will take up time. The process will take more time than originally anticipated so some flexibility is necessary. If software or equipment is not working properly, begin with making sure all connections are stable and connected properly. After that one can start troubleshooting each individual piece of equipment from the top down. And a very important reminder is to be aware of your surroundings at all times. One bump on the tripod will result in a re-shoot. Luckily we haven’t ran into that issue yet.
Another time while doing RTI, after setting the focus, we forgot to set the focus to manual on the camera. The camera ended up changing focus right before the shoot without our knowledge. After several shots we realized the change and had to start over. One should check the focus again immediately before shooting to avoid a re-shoot.
Photogrammetry uses a separate software than that of RTI. On our Photogrammetry test we were being extremely precise on camera placement by using measurements. A chalk line or measuring tape makes the process quicker so that one can visualize distance between the subject. Our attempts at being extremely precise were taking up a lot of time, but in reality the software still manages to recognize familiar points and string them together. We had to be precise in our distance from the subject but not by the centimeter. One can successfully do Photogrammetry without a tripod, moving laterally along a chalk line. It took several long attempts to come to that conclusion.
As Mark and Carla warned us in the beginning of training, its a fire hose of information. There is lots of terminology and lots of equipment to interface with. We were able to get some great equipment troubleshooting tips from Carla and Mark during this first week because there were plenty of equipment problems. There is nothing better for familiarizing oneself with a piece of equipment than attempting to fix it when it is malfunctioning.
As for training, It is hard to visualize the angles the flash needs to take in the RTI capture process. We are told to picture an umbrella that surrounds the artwork that the camera flash has to follow. This visualization requires practice. It would be of tremendous help if there was some type of visual guide. Very steep learning curve, with software, equipment, techniques, do’s don’t, and art safety. The huge payoff was the creation of our first successful RTI image with an Okeeffe painting and an image of the front of the research center here in Santa Fe captured using photogrammetry.
What I learned from our field work is this…mosquitos stink! Bring suntan lotion and bug repellant when doing field work. Setting up is 90% of time taken in RTI and Photogrammetry. Organization is essential with equipment in specific bags, and labeled. Makes packing up and setting up easier and increases efficiency by a huge factor.