Mikebart: A Question On Normalmap Creation

[SneaksieDave]

mikebart, if I may ask a question on your wood panel normalmaps? I'm wondering what techniques you used to create, for instance, the normalmap attached below.

 

I can see that it is hand-stitched together. The bottom is the top inverted; the right is the left inverted. However some things are still a puzzle to me:

 

What did you do to invert them? I'd read a trick about inverting the green channel to flip the normals, but that apparently doesn't apply here.

Did you model the slant, and then just invert it in the model?

Did you model all of the grooves, or are those overlaid textures?

Same for the fine details like smudges and scratches - modeled or overlaid in? If the latter, at what stage (before or after the normalmap is created)? How is this done? For all I know, there could be ways to get a normalmap straight from a textured model (thus getting height info from both geometry and texture) within a modeling app...

 

Overall the image is very clean and very deep, and these kinds of results simply cannot be gotten from image editing and running it through a normalmap plugin (AFAIK), so I'd like to learn the techniques if you'll share.

[OrbWeaver]

I obviously can't answer for Mikebart, but that is the sort of thing you can do with a combination of renderbumpflat + ASE model (for the regular pattern/grooves) and a plugin-generated image normalmap (for the "roughness"). You can combine normal maps together in Overlay mode in the GIMP, and presumably Photoshop as well, in order to build a more complex surface.

[SneaksieDave]

Right, I believe we were once discussing this with Oddity. I tried doing the overlay, as it is the most straightforward sounding method, but it always looked bad. Kind've "just laying height over height doesn't necessarily create proper height"-looking, AKA, "light blue next to dark blue overlaid on pinkish does not create something realistic." Maybe I was doing it wrong before and need to revisit.

 

I actually have specific interest in the how-to on this right at this moment, as I am making (well, experimenting with) an ASE for a renderbumpflat for some (really nice IMO ) door photos I took at Princeton University over the weekend, and want to have both the deep cuts only achieved with renderbumpflat, but also all the detail from texture imperfections and variations.

[OrbWeaver]

Right, I believe we were once discussing this with Oddity. I tried doing the overlay, as it is the most straightforward sounding method, but it always looked bad. Kind've "just laying height over height doesn't necessarily create proper height"-looking, AKA, "light blue next to dark blue overlaid on pinkish does not create something realistic." Maybe I was doing it wrong before and need to revisit.

 

It may not be exact, but it's the closest blend mode I could find which gave a reasonable result. You should run the combined image through the Normalise plugin again but with the conversion mode set to "Normalise only" -- this ensures that all of the normal colours are valid (because Overlay itself does not guarantee this). Unless you're doing something really wacky, the result should be acceptable with this technique.

[ascottk]

I use grain merge with the detail layer @ 50% (or somewhere around there) in the gimp.

[PinkDot]

There's also a small trick - not everybody might know this - but if you overlay normal map made using nvidia filter onto other normal map you have to go to blue channel, and scale down Levels by two, so the blue channel is not too bright. The result is more sharp normal map.

I found it on this site: http://www.poopinmymouth.com/tutorial/normal_workflow_3.htm (there will be explained it probably better, cause I'm too tired at this moment for more advanced english language expalations...)

[SneaksieDave]

First, I would have to welcome the gimp into my life. I tried it once and did not care for it at all (especially the crashing with trying to do this). Maybe I can find the photoshop equivalents...

[SneaksieDave]

The forum isn't allowing me to edit above. Great link, Pinkdot. I'll have to give that a go.

 

Also, I finally found the post I was referring to:

http://forums.thedarkmod.com/index.php?s=&am...ost&p=95847

 

 

Edit: aha, I think it was another case of "to" + ": " setting off forum alarms.

[mikebart]

I basicly modeled the door as a highpoly model and projected it onto a plane of the same size in 3ds max.

 

But there is a difference with the method I use as opposed to the most commonly used method of only including the geometric information needed to produce the normal map in the highpoly model.

 

I include the diffuse, specular and bump maps in the highpoly model itself. The bumpmap and the specular maps are just copies of the diffuse desaturated and adjusted to suit.

 

When the high poly model gets projected onto the flat plane the diffuse, specular and normal maps get rendered as seperate textures, the bumpmap which was included in the highpoly model is now added onto the final normal map perfectly, which is something difficult to acheive using the normalmap plugin in PS.

 

You can even use normalmaps on the highpoly model itself and they'll get added to the final one

 

If you havent read my tutorial yet i'd recommend giving it a go: Baking multiple textures from a high poly model

 

Its not the only way to do things though, its only useful in some situations depending on what you're doing sometimes you cant go past a PS generated normalmap for certain things, it all depends.

[SneaksieDave]

Cool, I'll check that out too. That's pretty incredible looking stuff in that thread, and your WIP thread.

 

I also tried the Ben Mathis tutorial Pink linked above, but so far it hasn't worked at all. I must be screwing something up, or maybe an "obvious" step isn't being explained (and isn't so obvious).

[sparhawk]

I hope somebody is putting the findings onto the wiki as tutorials.