New rendering technique Allows for loading multiple .ptm files of same scene
User can switch between loaded .ptm files
Presenter
Presentation Notes
My initial goals for this project were to finish what we started in the freshman class. The idea of a multispectral PTM device originally meant to split white light into RGB channels and to use UV and IR illumination as well. I wanted to find a new rendering technique to load multiple .ptm files of the same scene so that the user can switch between which channel they want to see the object illuminated with.
+ Project Design: Structure
Style: Geodesic Dome Rotating Arm Hinged Arc
Pros • Low cost • Short construction time • More time to focus on software • Website with dimensions
• Open design • ~3 illumination points • “Small”
• open design •~ 4 illumination points •Low cost
Cons and Challenges
• Closed design • Clustering LEDs • Been there, done that • ~24 illumination points
• How do I motorize a rotating arm? • Separate camera setup
• Hinging the arm
Presenter
Presentation Notes
I had 3 ideas for designing the structure of the system. The geodesic dome was very simple, cheap, and easy to do. However, it would use a lot of illuminators, cancelling out the low cost of the design. It would be easy to build the structure itself but wiring and controlling would be more difficult due to all of the LEDs we would need. Rotating arm along a circular track was the next option. This solution is ideal for mobility and it would ease the process of capturing the images. However, I would have to figure out how to motorize the arm to stop in specific positions which is way over my head. Learning how to do so would take too much time out of the rest of the project’s parts. The final structure plan was a hinged arc. It has the open design that the rotating arm offers but is more achievable. It also shares the low cost feature of the geodesic dome.
+ The winner is…
Hinged arc! Best balance of challenges and current skills
Presenter
Presentation Notes
The hinged arc provided the best balance of challenges to overcome as well as using skills I already have.
+ Illumination: which wavelengths do I use? Original plan: use white light and IR illuminators Only decent IR illumination with 30 second exposure
Let’s reconsider our priorities… Source images in non-visible spectrum
Or working device that simply splits channels but can be modified for other uses later on
Presenter
Presentation Notes
My original plan was to use both white light and IR LEDs but the only decent exposure I could get with the Nikon D50 took 30 seconds. I could have used a scientific camera but learning how to operate it would have cut into too much time with other aspects of the project. After reconsidering priorities I decided to use the white light flood LEDs we already had, cutting down on cost and production time. I would split the channels of the white light illuminated images and offer 4 different kinds of PTMs to be used. This model can also be modified to add additional illuminators later on.
+ Use white floodlight LEDs
Filter the light Too much work for the user
Intern couldn’t find accurate colored filters in time allotted
split channels in processing MATLAB splits into three 8 bit images
PTM Fitter needs 24 bit images
Layer the channels so they are 3 dimensional again
Presenter
Presentation Notes
I debated between filtering the light and splitting the channels, but the filters were too much of a hassle to switch each time. It was also more difficult than expected to find correct colors for the filters. I used a MATLAB code created by one of the summer interns to automatically split the images post processing. We had to stack the black and white images because the PTM fitter software can only receive 24 bit images in order to create accurate PTMs.
+ Camera Nikon D50 is available and
free
Lenses Sigma 14 mm
Doesn’t focus in IR
Too wide, can see LEDs in corners of images
Stock lens 18-55 mm
Falls out of focus
Coastal optical 60 mm UV-VIS-IR
Small field of view
Not necessary
Presenter
Presentation Notes
The Nikon D50 was still the best choice because of how easy to use and FREE it is. I stuck with the stock lens because the Sigma 14 mm didn’t focus in IR and was too wide for the device.
+ How to control the camera
Mac or PC? PC: Dome used IR trigger from Nikon remote
Wires easily came undone
I want to try something new
Mac: GPhoto2
Command line camera control
Issues encountered:
PTP permissions
Simply capturing the images overwrites previous images
Use capture-image-and-download to ensure that all data is collected
Presenter
Presentation Notes
I had to choose between a Mac and a PC to control my system. I could have used and modified what we already had made, but I wanted to try using the Mac since it hasn’t been done before. I found a command line control system for the camera called Gphoto2 that allows us to capture and download each image as it is taken.
+ Illumination Control
MATLAB Jeff Pelz
Designed to turn on one switch of a relay at a time, turn off, continue
Written to control 4 switches (I have 4 LEDs!)
Waits for camera to capture image before moving on
Encountered LOTS of issues
Google
Thomas Kinsman
Glenn
Jeff Pelz
Interns
Presenter
Presentation Notes
Jeff Pelz helped me find a relay and provided a code for me to use to turn it on. I have 4 LEDs and the code was written for 4 switches, so it worked out perfectly! I worked out my issues using the sources listed on this slide.
+ Channel Splitter
ImageJ For an unknown reason PTM software won’t load images sent
through ImageJ
MATLAB seems to always be the answer Splits channels
Layers them into 24 bit images
Labels each channel of each image respectively (_red, _green, _blue)
Creates directories labeled “red,” “green,” “blue” to save channels
Presenter
Presentation Notes
We tried using ImageJ to split the images but the PTM software wouldn’t load the images once ImageJ had touched them at all. MATLAB worked a lot better and we were already using it to control the lights so it made sense to keep it all in one space. The code added labels to each image and separated them into files for each channel.
+ Building a PTM
Couldn’t test RTI builder on a Mac with .lp file until we had a repeatable structure Betsy is only controlled by PC
RTI Builder wouldn’t load the .lp file Contacts: classmates, Cultural Heritage Imaging, Tom Malzbender
Incorporate PC Gphoto2 works on any system EXCEPT Windows Replace .lp file from Betsy with new .lp file Transfer files to PC Use the Hotkey already in place on the PC to create .ptm file
Highlight-based PTM Glossy ball More work for the user
Presenter
Presentation Notes
The RTI Builder wouldn’t work on the Mac with a .lp file, so you either have to transfer the images to a PC or image with a black ball. We couldn’t just switch to a PC because Gphoto2 doesn’t work on Windows.
+ What’s next?
Arm can be easily removed and replaced
More light sources IR UV Solux bulb
Block out ambient lighting
Get RTI builder to work on Mac
Test newer versions of RTI builder on PC to further investigate differences
Web-based .ptm file for easier viewing
RTI builder easier to get along with
Presenter
Presentation Notes
Future tasks: The arm can easily be replaced and removed for modification. More light sources can be added. The system needs to have ambient light blocked out so something could be added to do so. Figure out why the RTI builder doesn’t work on a Mac. Turning the .ptm files into web based files would make them easier to view and share. Make RTI builder easier to get along with.
