Modeled And Painted Normalmaps?

[SneaksieDave]

Got a bit of a conundrum here, and I'm wondering if there is a simple solution I don't know of.

 

What do you do if you want a model's normalmap to contain both modeled geometry (e.g., roundness, panels, buttons, etc.) from a highpoly version, but also painted geometry (scratches, grooves, noise)?

 

It occurred to me if I make a normalmap from a highpoly version of my model, it might be fine for large details and modeled shapes, but it will be absolutely devoid of any realistic scratches and noise (and those will not be modeled). How to get around this, is there a way to combine two normalmaps, either with blending in the material, or within photoshop?

[OrbWeaver]

How to get around this, is there a way to combine two normalmaps, either with blending in the material, or within photoshop?

 

You can blend two normal maps together, I have done this many times in the GIMP. The normal blend mode doesn't work, you have to use something called "Hard light" or "Soft light" (I have no idea whether there are equivalents in Photoshop), and then re-run the normalmap plugin in "Normalise" mode.

 

You can also use the addNormals() function in the MTR definition to combine two normalmaps in-game.

[SneaksieDave]

Great! I'll try an experiment and see if I can get the combine method working.

 

As for addNormals(), I could've swore I saw something like that. Okay, but would that waste twice the memory, or does it get blended automatically?

[OrbWeaver]

I assume that it blends the two normal maps into one main map, which is then sent to the graphics card. As far as I know there is no shader support for blending normalmaps on the GPU, so this would have to be done by the engine in an image preprocessing stage.

[PinkDot]

In Photoshop there's Overlay blending mode which does the job for any amount of normal maps you wish to.

 

AFAIK doom engine accepts also height maps which are converted to normal maps and mixed together with existing normal map while loading, but it's better to do it in Photoshop cause in that way we save some disk space The Mod is going to use on HD and probably some loading map time...

[SneaksieDave]

Okay, so doing it by hand might have performance benefit, and you can hopefully eliminate unpredictable results.

 

Well here's what I got, it looks like it works (mostly). I started with two white images and made fuzzy black squiggles. I then used the normalmap plugin to create a normalmap. So far, no problems. Then, I used the normalmap plugin to convert to height - I couldn't find any way to combine them both as normalmaps (clue me in if I just don't know the trick). At this point, if you look really close, you'd see there is a slight quality problem; some banding occurs from top left to bottom right. No idea why. Then combine with 'screen' (soft and hard light didn't work well), and re-normalmap. At this point, the noise from the banding is quite worse, but I'm hoping something can be done about that.

 

Should I not be converting to height first? I don't see another way to blend what is essentially multiple colors with a specific meaning.

[SneaksieDave]

PinkDot: I just saw your response.

 

Here's what I get for overlay. What am I doing wrong?

I assume:

1. copy one normalmap, paste it into a new image

2. copy second normalmap, paste in into an overlay layer on the new image

[oDDity]

I covered this a year ago in the documentation forum.

http://forums.thedarkmod.com/index.php?showtopic=2341

[SneaksieDave]

Great! I'll try that too.

 

Edit: But the problem remains - I don't have heightmaps to work with... I can generate them but it makes noise. I'm currently trying to deal with that noise, because the normalmap generation without it works great.

[oDDity]

A heightmap is just a black and white verison of your texture, maybe woth the levels tweaked abit to make it more pronounced.

[OrbWeaver]

Dave, your overlay image is correct. Just run it through the normalmap plugin in Normalise mode to ensure that the values are within the required range (you may not even need to do this, but I always did just to be safe).

[PinkDot]

Sneaksie - well, yes - it looks weird for such things but it would look better if you wanted f.e. to add some scratches or small organic bumps onto your normal map (just like you've mentioned in your question).

[SneaksieDave]

Right, levels helped quite a bit to get rid of the noise/gradient shit, which must be a defect in nvidia's plugin. Black + Black = strangely fading Grey? No, nvidia, it's not...

 

When I did the normalize to the overlay image, it came out terrible. I'll fiddle with some settings.

 

Here's the result of normalize on the overlay. Looks pretty much the same.

[SneaksieDave]

And here's is nvidia's idea of black + black. Look closely and note the gradient from top left to bottom right, fading from black to not-quite-so-black. When re-normalmapped, it shows up pretty strongly.

[SneaksieDave]

And here's after a bit of levels adjustment and a gaussian blur to add back in some removed sharpness (edit: duh, I mean smoothness). Decent results, I think? (compressed as JPG here of course)

 

Compare to the first attempt: http://forums.thedarkmod.com/index.php?s=&am...ost&p=82172

 

Edit: as always, thanks for the guidance guys, you're a wealth of information.

[OrbWeaver]

And here's is nvidia's idea of black + black. Look closely and note the gradient from top left to bottom right, fading black to ... less black. When re-normalmapped, it shows up pretty strongly.

 

Huh? I can't see any gradient in that image, looks like solid black to me.

[SneaksieDave]

Grab that image and adjust the levels... you'll see it. Here it is below after shifting the midrange toward dark. It really shows up when doing a normalmap or normalization filter. The whole thing slopes upward (since it's getting lighter). Since it was only adding two basically black heightmaps together, it's probably a filter bug.

[OrbWeaver]

Ah yes, now I see it. Strange.

[SneaksieDave]

Gah. Even crappier is that the normalmap plugin is unable to convert some things to decent heightmaps at all (I have no idea why - it just wants to turn it into a gradient field with a few dents, which is very much not what the normalmap looks like), and worse, even if it did work, even at 4 sample and a decent height, it washes all the detail out. That's even with trying it with some of the character normalmaps - all detail lost. So it looks like the approach of normalmaps -> heightmaps -> blend -> normalmaps is out, afterall. Sure it works for a blurry squiggly. Just not for anything useful.

 

So I'll be trying suggestions above/what Oddity posted in the docs forum. That should keep crisp detail, assuming the heights don't compete (which I guess they must not, if this works, but I don't understand how).

 

Next I have to figure out the best way to skin something; getting around weird shapes (I assume this involves transforming base textures to contour to needed shapes) and avoiding obvious seams. No idea what to do there.

 

Sooner or later I might have a nice product.

[OrbWeaver]

Converting normalmaps to heightmaps is indeed a non-starter. There is also no need for it, since the overlay blend technique works perfectly well with normalmaps.

[Dram]

Well the Painmon uses heightmaps for their displacement mapping (parallax or whatever). It looks bloody impressive too.