OTOY Forums

How do you guys handle the multiple maps coming out with figures now. It seems to me, that the current thinking is to have high frequency details like pores and stuff be contained in the bump map, while broader features are found in normal or displacement maps.
How do we handle this with octane, hwre only one of these is allowed?

I know you can double up your material in the NGE, apply bump and normal/disp and then mix it again. This is a bit messy, and it seems that the more material types you use, the more VRAM is consumed.

I'm thinking of somehow baking the bump map info into the normal map, and then use that as a single map? Are there theoretical reasons that this is a bad idea?

Since bump and normal maps perform the exact same function in a slightly different way (black and white vs RGB), I tend to pick whichever is more detailed (when both are present, which is kind of pointless, considering the previous information). This is most often the normal map, when it is present, at least from what I've seen, it's just harder to see, since it uses such a broad range of hues to represent surface normals (which is why it is usually more detailed, the method itself allows more details than 8-bit greyscale). I have not played with G3F extensively, by any means, so which maps are provided at what detail level may have changed quite a bit recently, but the principles remain, as they are the structure of the map types themselves. Prior to OcDS version 2, I'd decide based on how many of whichever map type I had slots left for and what all still needed a map, but now it's pretty much whichever looks better. Just my two cents on it.

Generic, uninformative answer: If it looks better to you, go for it

Haha yeah, that's also how I've been thinking about it. But have a look at the maps with V6 for instance. But the thing is, it's not that one map is "better" than the other, they contain very different kinds of information, that should both be present in the render :-/

Compare normal and bump maps for the stomach part of the torso map. On the bump map you have all the pores and small imperfections. On the normal map you have the detailed definition of the abs. You really need both for the full effect.

A lot of information on this topic is scattered all around the forum this is a try to combine some of it.

Combining Bump / Normal and Displacement maps in OctaneRender

In the early OctaneRender 2.x versions it was not recommended to actually mix Bump / Normal with Displacement maps.

Nevertheless developer aoktar found a workaround that was shared a while ago by bepeg4d:

Displacement + bump trick

A material with a bump map is plugged into both slots of a mix material node.
Then the displacement node is plugged into the mix material node as well.

viewtopic.php?f=87&t=48024

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Differences of bump, normal and displacement map

Some users may still struggle with this.

Bump and normal maps do not actually alter the geometry. As a result the bump and normal elements of a surface cast not physically correct shadows.
Displacement maps do alter the geometry. The displaced surfaces are casting physically correct shadows.
Calculating displacement does use more system resources than bump or normal maps.

IF your goal is to create photo realistic images you should not AT ALL use bump or normal maps on objects that are visible in the foreground.
- Use displacement maps or HD morphs


In the past: Mixing bump / normal with displacement maps in the early days of computer graphics

In the early days of computer graphics system resources were much more limited than now.
Calculating displacement was considered a huge effort. The same limitations may still apply today when creating game models.

If the benefit of displacement in a specific area was only considered minimal bump / normal maps were used. As a result some studios started to actually mix bump / normal with displacement maps on the same surface.

Some artists at DAZ3D picked up on that technique and unfortunately did not stop using it even now when there are enough system resources available on most users systems.

Now: Displacement maps for foreground objects - Bump / Normal for background

If a so called "hero object" is in the foreground it makes sense to use displacement maps for all surfaces and all the tiny details.
Allready at 1920x1080 and especially at 3840x2160 resolutions and up you can spot very well if shadows are calculated properly or not.

If an object is in the background nevertheless there is still not much point on using displacement. Then it makes sense to use bump / normal on all surfaces.

IF artists would actually create their characters in Zbrush it would be no effort at all to provide the customers with two different complete sets of maps:

- one displacement map set for close up shots
- one bump / normal map set when the character is used in the background.

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Using bump maps with a displacement node

Some bump maps can be used in the displacement slot.
There are different systems of calculating bump and displacement maps.

- Mid level gray as 0 point. gray to black will cause negative displacement inwards, gray to white will cause positive displacement outwards.

I noticed that a lot of those "grayscale" bump maps provided with DAZ3D characters seem to just be painted / edited in photoshop and therefore will not yield an accurate displacement. In addition those maps tend to give a balloon effect in which the whole figure geometry is enlarged if there is not a proper offset used.

Rule of Thumb:
The offset value should be half of the height value as a negative number.

Example:
Height: 0.00004
Offset: -0.00002

Side Note:
OcDS uses different units as OR standalone.
You cannot simply copy and paste displacement values between the two versions.
Make sure to check if the units are meter (m) or centimeter (cm).

- Maps with black = no displacement and white = full displacement

Those maps work best in OctaneRender / OcDS from my experience.

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update / edit:
removed parts to stay on topic.

Thanks for the mix material tip, I've been searching for a while but could not find it

As for DAZ materials, I think you're grossly overestimating the thoughts that go into making most of the products.

If you look at the maps, for most vendors it's usually just a question of running a photoshop filter on the re-used heavily jpg compressed diffuse map and calling it a bump map. There's a Merchant Resource kit for G3 specifically for Iray, which has tons of baked in shadow material, including the huge shadow under the buttocks. People either don't care or understand how these maps should be put together.

So for now, we need to figure out how to use the provided materials or convert them into something useful. There's tons of software that can convert and merge bump and disp maps. With Zbrush (and probably others) you can apply any combination of maps to your figure and bake any map you want.

In the absence of proper displacement maps, I've been messing around with normal maps a bit more.

For me, the issue right now is that I have to chose between these maps:

Bump: Small details like pores and moles
Normal: Body/muscle definition and refinement.

These maps are supposed to be used at the same time, but with Octane, we can't.

It turns out that this program can convert bump maps to normal maps: http://www.xnormal.net/
This one can combine normal maps, using the proper math: http://www.planetinaction.com/software/ncombiner.htm

Both are free

So:
1: Convert the supplied bump map to normal map with Xnormal
2: Use Ncombiner to combine your converted normal map with the supplied normal map.
3: Render.

thanks for sharing, i could see that being useful. going to download now.