Soft light blend mode technique for normal mapping

PaK

There is a technique to blend a layers that are higher in your heirchy (in photoshop) and set them to soft light, and change the blue to 128 isntead of 255. What you are essentailly doing is overlaying details without causing a saturation/color shift in the normal mapping color space.

I just dont know howto do that shift from 255 to 128. can someone help?

-R

thnom

http://www.poopinmymouth.com/tutorial/normal_workflow_3.htm

Delaney King

I use overlay on the channels. Seems to be ok.

FAT_CAP

ALT + L to bring up the levels panel - select the BLUE channel from the RGB dropdown menu - then replace the 255 value with 128. Then set the layer to OVERLAY mode.

Rick Stirling

Replace with 127 folk, thats a 7 on the end.

1 to 256 = 128, but since PS uses 0 to 255 its 127 you want.

sinistergfx

To rick you listen. 127 is the true half.

I have this overlay method and an nvidia filter normalize set up in actions; because they end up getting used a LOT when working over your normal map in PS. Depending on the texture, sometimes I spend more time in PS on the normal map than on the high poly geometry.

poopinmymouth

I'll update the tutorial, I think though that 127 and 128 are close enough to not matter *too* much.

Also Sinister, I mentioned setting it into an action and even have said action available in the tutorial.

sinistergfx

Yeah, I know.

But your action was WRONG. :P

KDR_11k

For Doom 3 you can also save all layers separately (with the overlays still reduced to 0-127 in the blue channel) and use the addnormals() function in your material. That allows you to use different overlays for different skins.

PaK

I did a control test with this technique, and though it did improve the color shift a bit it did not maintain the hue/value integrity I was hoping for. I would post the results but I really think I'd get in trouble for that.

Great technique though ben. This pipeline I'm developing is quickly becoming the most complex and gratifying assignment i have ever had in my career. i love this job *woot*

-R

sinistergfx

PaK: are you using soft light or overlay?

PaK

I tried both, there is a hue/saturation shift no matter what you do. There is no way I have found yet to add detail on a layer overtop and maintain tangent space normal map colors.

-R

poopinmymouth

that's because you can't overlay it without changing them. That's the whole idea, to change it. When you put a layer into overlay mode, it is essentially modulating each channel, by the channel above it. darker than middle grey, and it darkens it, lighter and it lightens it. If your photoshop overlay is only details, it should only change the layer enough to add these details. If it is shifting it too far, you are most likely either have your scale set too high in your nvfilter options, or your b&w layer wasn't just details, it had large scale volume changes in it in addition to the smaller scale noise you were looking to add (like just running the filter on a greyscale version of your color map)


Only remote way I can think of to be more accurate than this is to set up your low poly with a normal map that will render, as well as a bump map addtion, then rendering to texture again. But I'm just throwing out ideas and I've never tried that.

Oh yeah, I might not have made it 100% clear in the tutorial, so I'll go back and fix it, but once you are done with your nvfilter layer, you need to make a merged copy of it, and re run the nvfilter set to Normalize only, with height set to 1, and this will return the colors to safe tangent colors. I mentioned it, but I'm not sure how well.

PaK

that's a good point ben i forgot that normalize step. i'll try it tommorow and let you guys know if it solves my problem.

EDIT:
WORKED! Normalize made the difference. Thx again Ben.

-R