I have begun to explore using a smart phone as a viable tool for material scanning for real time computer graphics. I was inspired by a great article put out by the fine folks at Allegorithmic, about how to use most newer smartphones as material scanners. The article goes into detail about what kind of set up produces good results. It sounded relatively simple, and my smart phone seemed up to the task, so I figured I would give it a shot.
I had to get and build a number of things in order to make this possible. I managed to find everything used by the author of Allegorithmic's article, for good prices, including:
- x-Rite Colorchecker - This is a professional graded macbeth chart, used to for detailed colour correction in Adobe Lightroom.
- Manfroto Lumimuse High Power LED light - A high performing LED light that can be mounted to a tripod that is small and practical for this kind of project.
- 2 small tripods - the smaller the better, but stability is key. You want to get the smart phone pretty close to the material sample, as zooming creates unwanted noise.
- A modified selfie stick - modifications made to it include removing an end piece so that it could be mounted to a tripod as a make shift boom stick to hold the smart phone out at a distance, pointing down. A microphone stand could also work for this.
- Some string or thread and an object to tie it off to - The string is used as a measuring tool, attached to the tripod with the LED light on it. The process of capturing the material
- A small box, 12"x 12" x 9", with a 10cm hole on top, and a small hole on the side - you could make it out of something cheap like cardboard, but I figured I would be using this rig quite a bit for various projects, so I decided to build it out of a sturdy fibre board, with the help of a friend (Thanks again Ewan!). I painted it matte black on the outside, and matte white on the inside. The two holes in the box are made to be able to put the LED light inside, to photograph the transparency of a material sample.
To summarize the process, with this rig you just need to move your LED light around the material sample, at 45 degree increments, an take a photo of the material straight down with Adobe Lightroom Mobile camera, using either the Professional Mode, or the HDR mode. You need a fairly small (10-15 cm) material sample. You take 8 angled shots all the way around the material sample, with all other lights off. These shots are later computed to produce a relief of the three dimensionality of the material you're scanning. Then you turn the lights on, surround your material sample with some light diffusion (in my case the dull side of aluminium foil as its very cheap). This is done to capture the unbiased colouration of the material (with as little shadows as possible). If your material is transparent at all, you can then remove the LED light from the tripod, and place it inside the scanning box, to shine up through your material sample. A colour checking sample is taken after your 8th angle shot, and during the foil shot.
All of your 12 photos can then be synced and uploaded to Adobe Lightroom on your computer. Here you calibrate the photo's white balance profiles from the colour checker samples. This way you get the true colour. Then you can Photomerge your pics, to align them in Photoshop. Crop them down to isolate the material scan, and resize them to 4096 pixels. Export them as TIFF to be imported into Substance Designer 6.
This is when the real magic starts :)
Substance Designer 6 comes with some fancy new tools to process material scans, including multi angle processors, multi cropping tools, multi colour equalizing tools, and smart auto tiling tools. With these features, you can input multiple shots, and process them with precision. These tools in concert make it feasible to produce a pretty great looking result in a matter of minutes.
For my first tests, I decided to go with a non transparent material to familiarize myself with the process. So I had some pieces of cardboard kicking around, which became the subjects of my first scans. From the start of scanning, to the final render of each material, was about 2 hours. I was very pleased with this result, and I know that with a little bit more attention and time, I could get a lot more out of the new tools in SD6, and my new rig.