Tell me all you know about Normal and Displacement Maps and A:M

[Heiner]

Hi there,

every once in a while (mostly in my holidays) I return to A:M and try to make it really work for me. Still dreaming of an animators career, doh.

However, one point where I still have huge problems with are Normal and Displacement maps. While mighty and powerfull I was never able to make them really work for me. When I render in A:M I only get unpredictable results, which by far not what I expect. Therefore it woud be nice, if you could tell me what to look for when using this kind of maps.

Info about where you do the maps, how you export, what type of Normal adn Displacement maps you us would be also cool!

Thanks in advance!

[robcat2075]

Can you show us one of the unpredicted results?

[Heiner]

Unfortunateley not right now, because I am sitting in the Philippines with no real acess to my work. But what happend was mainly that the deformation and the displacement was not smooth. Instead I got very aliased results. As soon as possible I post samples.

Regards,

Heiner

[robcat2075]

Normal maps are like Bump maps in that they only change the shading of the surface without actually changing the shape. I tend to use bump maps rather than Normal maps because they are easier to create in a paint program.

 

 

Basic tips for Displacement maps:

 

-The grayscale range of TGAs, PNGs and JPGs only has +/-127 steps so very slight slopes or slopes on large lumps can start to look stair-steppy. If you have a way to paint in a high dynamic range format like OpenEXR, that will allow you many more steps between zero and peak.

 

-Extremely steep protrusions rarely work well with Displacement.

 

-Displacements have a way of flickering in animation as the angle of the camera to the surface changes. I have found that can be mostly eliminated by rendering at triple size and scaling the finished render back down in post. For example a 640 x 480 image would be rendered at 1920 x 1440.

 

In a normal Final render that will cause a noticeable render time hit. If you are using Multipass you can save some time by using fewer passes... a 1920 x 1440 image done with one pass and scaled down to 640 x 480 will have the same level of anti-aliasing as a 640 x 480 image done with 9 passes.

 

 

 

 

 

 

[Heiner]

Thanks for the answer.

But, where do you generate the maps? What settingds do you use?

Regards

Heiner

[robcat2075]

Thanks for the answer.

But, where do you generate the maps? What settingds do you use?

 

Displacement maps are typically painted like bump maps are.

 

I have generally painted them in conventional formats and lived with the +-127 problem

 

 

 

My version of Photoshop only supports some basic processing of HDR formats like OpenExr and I can't actually paint directly in it.

 

I have tried converting my 8-bit grayscale maps to 16 bit and then applying a slight blur to get the extra steps but that's just experimental.

 

Most of what i have done with displacement has been with materials rather than bitmaps. Materials don't have that 8-bit limitation in the greyscales they can make

 

Tanks, but no Tanks

[Heiner]

Hmmmm, thanks for that.

I was hoping someone uses zBrush or such ...

[robcat2075]

I was hoping someone uses zBrush or such ...

 

I imagine it's possible but I've never used Zbrush. Someone has been able to move maps back and forth between A:M and zBrush I recall.

[R Reynolds]

One way I've found to ease the creation of normal maps is to apply a standard grey material to a flat surface with bump percent turned to 100%. Then I render that surface with the normal buffer turned on. That converts the material bumps into an image which, when applied as a normal decal, I find demonstrably better than the original material. For evidence I present the following comparison.

On the left is a render of a flat plane with a bump material which is just Crumple with its default values. On the right is the same plane with a normal decal derived from the material on the left. Although the normal texture is a bit soft due to the built in decal filter effect on a relatively low res (309 x 682) image, I still find it more convincing than the bump material.

 

Since I'm typically using normal decals to replace modeling a lot of repetitive details I usually model those single details, turn them into normal renders and then apply them as decals. For example the tender of my steam locomotive.

All the rivets, the joints between the plates and the coal surface are all normal maps.

[robcat2075]

Would it be more convincing as a displacement?

[Heiner]

Hmmm,

looks nice, but I think also that displacement would be better. Especialy when you check the area where the coal bumps onto the tender. Thats not really convincing. But then, whe you do not have sich hard contrasts of materials/objects it might work ok ...

Regards

Heiner

[Guest]

 

Would it be more convincing as a displacement?

 

That question led to some surprising results. Crumple's bump parameter generates surface texture that can't be reproduced with a bump or displacement decal.

 

I took the 8 ft. x 4 ft. plane (colour = 256, 256, 256) with a default crumple material and did a head-on screen render. The first image is that screen grab.

 

The next image shows that plane (colour = 128 , 128, 128) final rendered at an angle showing the default crumple bump texture.

 

I deleted the material and applied the first image as a bump decal at 100%. The 3rd image is a final render of that plane. These bumps don't bear much resemblance to the bumps produced by the native material.

 

I switched the decal to displacement at 100%. The 4th image is a final render of that plane and is identical to the bump except for the edges which now are subtly distorted to follow the texture.

 

The 5th image shows the result of applying a normal decal derived from the crumple material (as described earlier) which, once again, looks nothing like the bump or displacement decal result.

 

The displacement decal edge distortion becomes obvious if you apply the decal at 2X size and crank the decal to 500% (6th image). But it still doesn't look like the original material.

[Heiner]

Hi there,

here is a sample of the issues I am having with displacement maps. The general impression is there and also the displacement effect. But there is also a heck of a lot of artifacts and I dont know where they are coming from ...

For comparrison there is also a image of the model in realtime ...

Regards,

Heiner

[Rodney]

That looks to me like a classic example of inverted normals.

If you turn 'Display Normals' on (in Tools/Options) you'll be able to see if that is the case.

If it is then use the Group Select tool to grab those patches and then Right Click and select 'Flip Normals'.

 

In your case there are two indicators that inverted normals might be the cause. The first is the black discoloring. The second is that the models appears to be displaced in the wrong direction at those areas.

[Heiner]

Hi there,

@ Rodney> Good point, I will give it a shot ASAP!

Regards

Heiner

[Heiner]

Hi there,

the reorienting of the normals took away the weird look. That leaves the strange artifacts and the seams ... any ideas on that and how I may get better seams?

For stills that is ok, there it could be fixed with a paint programm, but for animations its not working at all.

Regards

Heiner

[Fuchur]

The problem I see is that, you are using no 5-point-patches but instead a star-intersection (more then two splines crossing in a point between the fingers). That will result in the hard edges there...

 

Have a look at my tutorial here... it is about a foot, but in the end, it is the same... .

http://www.patchwork3d.de/erstellung-eines-fusses-181-de

around 6:00min it starts to get interesting.