Author Topic: Hard or softlight in material scanner  (Read 444 times)

Tok Tok

Hello!

I'm not sure if I put this in the right section but there wasn't a section for scanning materials.

I'm currently building my own material scanner and to do this I'm following the blog of Dave Riganelli and Allegorithmic, but I see two big differences between the two. Dave Riganelli is using hard lights to light the material and on the Allegorithmic blog they say you need a big soft light for the best result. So before I start building my scanner I would like to know the difference between the two options and which one is best.

Does anybody have experience with this?

J

Anthony Salvi

Hi Tok Tok,
Hard or soft lights depend on the algorithm you used. What we have experienced at Allegorithmic is simple. Our algorithm in Substance Designer works better with soft lights.
Why?
Because with a soft light, you have enough shadows to compute a Normal map and enough information (not too dark shadows) to compute a nice Albedo map.
One thing to note with the soft light configuration, in some cases, you need to boost the Normal map to get a stronger result.
All steps are described in this tutorial https://www.allegorithmic.com/blog/your-smartphone-material-scanner-vol-ii
I hope it will be clearer for you.
And the best thing is to experiment by yourself and find the best configuration for your usage.

Tok Tok

Thanks, that's what I wanted to know. I have to change my design a little bit, soft light is harder to make than just a spot.

In a youtube video you can see someone putting some leather material in a boxed 3d scanner with soft lights. Are there any specs/tips on how you did the gradient soft light in there?

I don't have a license for substance designer so I don't know much about it (best algorithm etc.), yet, but I will buy it for this project. I'm very eager to test out the scanner once it's done!

Anthony Salvi

Regarding the specs/tips for a DIY scanner, I can only say this:
The Substance Designer algorithms are robust and flexible enough to produce good results even with this low-tech approach.
So, build your prototype and try it. That should work.
Last Edit: January 10, 2019, 01:15:41 pm

Eggfruit

Although I have no experience capturing surfaces (so take this with a grain of salt), I know that hard lights will light surfaces in a somewhat binary way: either lit or shadowed. Whereas soft light will create more gentle gradients as surfaces curve towards or away from the light source. This means that soft lights will probably capture curvature and the feeling of depth better, while hard lights probably capture very fine details better.

Also keep in mind that hard light can cause parts of the subject to cast shadows onto itself, which seems like something to avoid.
Esger van der Post.
Game design student and texturing addict.

Tok Tok

Yes I guess that's true but at the same time Substance Designer should be able to get the color information that is in the shadows in one picture back from the other.

Anyway I'm still building and went with the soft light approach. We'll see what the results will be.

Anthony Salvi

Don't hesitate to share your results.
And as soon as Substance Alchemist will be available, you will be able to use the same datasets with it.

Tok Tok

At the moment I'm still building (very busy with viz work) but when it's finished I'll share the results.

What is Substance Alchemist, do you have more information on that? The beta page looks really interesting!

Tok Tok

I finished the material scanner and posted the first results in this topic:

https://forum.allegorithmic.com/index.php?topic=28088.new#new