Editing normal maps manually...

pillowsama

I was just wondering if anyone here is familiar with any techniques to edit the normal map directly in photoshop...

I bought character modeling 2 and in the book it mentioned that it's easier to edit the normal map directly and more efficient too (for example, adding in pores and micro details) but I have no idea how to properly edit a normal map, can someone please help me out here? thnx!

HarlequiN

Grab the nVidia normal map plugin from http://developer.nvidia.com/object/photoshop_dds_plugins.html

Using this you can create a normal map from basically a greyscale heightmap (so you might paint the pores in a dark shade of grey on a 50% grey background, and then run this filter on the image).

Once you've done that you can overlay your pores normal map over your rendered from max normal map (that is place one as a layer over the other and select the Overlay blending mode). This next bit is important - Flatten the resulting image and run the nVidia filter on it again, but this time select "Normalize Only". This will attempt to repair damage to the normals caused by overlaying one on the other (it doesn't always work, but the failiure rate is pretty low if you're not overlaying dozens of maps at once).

That's the only way I know of to do it.

Ryan Clark

I'm gonna throw in a plug here my own software:

CrazyBump's mixer gives better results than a Photoshop overlay. It uses a different blend function which doesn't damage your normals.

If you care to try it, grab the beta from www.crazybump.com

MoP

Also worthwhile remembering to change the "Blue" channel's output levels to maximum of 128 (CTRL-L, select blue from the drop down, type 128 where it says 255 on the right at the bottom gradient slider thing).
This is because the blue channel contains the "forward" facing normal information and if you use Overlay blending mode it has a tendency to push the underlying layer off a bit.

I've got a Photoshop Action on F11 which runs the NVidia filter, then sets the blue levels to 128, then changes the blending mode to Overlay ... so once I've made my greyscale "height" layer I can just quickly get it blended properly onto my underlying normals just by hitting F11.

Rick Stirling

Is it not 127? (The difference will be minimal anyway.)

Ryan Clark

Ideally, it would be 127.5

pillowsama

WOW, u guys are AWESOME! thnx a lot!!! I've never had replies so fast on any forums before lol... My last topic was filled with replies and solutions withini a day too, this is great help! I'll definitely try these out and post my result thank you so much guys!

I've actually tried out the Crazy Bump beta already, it does give off a much better result even in generating height map as well, I'll make sure to grab the latest beta version!

Just a question, when painting a height map, wut's the contrast level that is recommended? just like any bump map? and ... is there a difference between bump map and a height map at all anyway?

Ryan Clark

Either way you round it, that step throws away half the detail in your blue channel. That's 1/6th of the detail in your whole map!

Is that much loss really acceptable?

I don't think it is.

HarlequiN

pillowsama - white is your highest, black is your lowest, with a full spectrum in between. You should be able to control the depth of the resulting normal, and using the full range of greys gives you the most control over your intermediate depths.

Ryan - sorry man, I knew about crazy bump, but at 2:30am I wasn't really with it.