Photogrammetry of leaves for an atlas

Scub

I'm wondering if anyone has a good method for scanning leaves for a leaf atlas, like you'd get from megascans. I assume quixel has some crazy lighting setup and special equipment for flat atlas scans like that.

Using a single image in something like Bitmap2material or knald gets that pillowy look and I haven't gotten very good results. I haven't tried using a full photogram software like reality capture, but I feel like that would get very noisy results that wouldn't suite something like leaves.

I'm looking at this program because you can do 4 photos with different light angles and that seems like it would be a pretty good way to do leaves, but I haven't forked over the $50 for it yet.
https://shadermap.com/tutorials/normal-map-photography/

Anyone doing anything else clever?

gnoop

You could do pretty much detailed up to  distinguishable  leaf veins  hi-res mesh of 20-30 mil  with close enough photos. 10 photos probably with a small shift/parallax.   

m4dcow

Scub said:

I'm wondering if anyone has a good method for scanning leaves for a leaf atlas, like you'd get from megascans. I assume quixel has some crazy lighting setup and special equipment for flat atlas scans like that.

Using a single image in something like Bitmap2material or knald gets that pillowy look and I haven't gotten very good results. I haven't tried using a full photogram software like reality capture, but I feel like that would get very noisy results that wouldn't suite something like leaves.

I'm looking at this program because you can do 4 photos with different light angles and that seems like it would be a pretty good way to do leaves, but I haven't forked over the $50 for it yet.
https://shadermap.com/tutorials/normal-map-photography/

Anyone doing anything else clever?

If you already have Substance Designer, their multi angle to normal node does pretty much what shadermap does as far as normals are concerned (doing 4 directions like that you could do this in photoshop yourself too.

I have been messing with foliage scanning for a long time myself, still in the process of making my latest scanner with lots of lights (check out my sig for the thread). I use a software called dabarti capture and it gives the best results in terms of normal maps out of everything I have tried, the prices is a bit steep if you are just messing around $(99), but there is a trial version which does up to 1k textures which you can try out.

One thing I would recommend is using a lightbox to shoot your leaves on, you are able to get translucency, but more importantly it makes it wayyyyyyy easier to generate your alphas. I have made large 3x3ft & 4x4ft ones myself, but you probably don't need one that large and can get something like this which is thin
https://www.amazon.com/dp/B013SHKTXO/

I'm pretty sure quixel doesn't use photogrammetry for their leaf atlasses, when you have stuff that is pretty much flat it isn't really worth it to go that route.

You might want to look at cross polarized lighting too, I use it to get my albedo and my gloss. Analyzing video clips of Quixel's prototype scanner they use that sort of lighting too, probably along with a lot more complicated magic to generate their textures many years later.

Scub

Wow I can't believe I didn't know about that substance node. I'll have to play with that this weekend. I was looking at making a lightbox too, and that may be my next project. I'm sure that multi angle technique runs into hard limits pretty quick though if there is too much surface variation on say a really wavy leaf or dead crumpled ones, so I'll have to try out a normal photo scan as well and compare.