topic Re: Texture filtering in VRED Forum

Texture filtering

Anonymous — Fri, 11 Jul 2014 08:06:43 GMT

Hi,
Is it possible to switch off texture filtering for ray tracing? I'm using super-detailed normal maps which look great up close, but at a distance the texture filtering makes the materials shiny as opposed to the roughness that the normal map would indicate:

Scaled down from 4K Rendered directly at this resolution

The behaviour is the same for non-raytracing, but I guess the fix isn't as obvious there as just switching off texture filtering.

Cheers,
Jens

Re: Texture filtering

florian.dyck — Fri, 11 Jul 2014 11:49:05 GMT

Hi Jens, did you change the texture's filter value / anisotropy in the material?

Another thing you can try: to uncheck "compress textures" in the Common section of material editor.

Re: Texture filtering

Anonymous — Fri, 11 Jul 2014 12:56:49 GMT

Thanks Florian!

Compress Textures seem to be switched off.

Setting Anisotropy to 0 sure made things better, but it still seems like some kind of texture filtering is going on:

4K 320x240

4K 160 x 120

So the problem remains, but the scale at which it occurs is pushed further. There's no magic preference setting to completely switch off texture filtering? Rendering at insane resolution and downscaling only solves the problem to a certain scale unfortunately, so I don't consider it the perfect workaround.

Thanks for the quick feedback,
Jens

Re: Texture filtering

florian.dyck — Fri, 11 Jul 2014 14:13:26 GMT

I don't know of a magic switch to turn filtering off 😞 I just looked in render settings and options and tried to find similar settings as I would expect in Maya, but there aren't.

file:///C:/Program%20Files/Autodesk/VREDPro-7.01/doc/vrRenderSettings-module.html#setRaytracingStillFrameTextureSharpness

there is a Python command for vrRenderSettings, I haven't tried if it sets the same settings as the anisotropy value.

setRaytracingStillFrameTextureSharpness(sharpness)

Sets the sharpness factor for texture sampling (advanced feature). WARNING: Changing this settings may lead to rendering artifacts!

Parameters: sharpness - The sharpness factor.
(type=float)

Maybe try other pixel filters for rendering (Mitchell Netravali 2.2 etc.)

Or try saving your texture in DDS format including mipmaps.

Also I am just a standard VRED user and I guess the development team from Autodesk knows some better answers.

Re: Texture filtering

michael_nikelsky — Fri, 11 Jul 2014 14:43:45 GMT

VRED tries to avoid moire artefacts and excessive noise so the bump maps will always be filtered.

On way to control the filtering a bit is by using the

setRaytracingStillFrameTextureSharpness

This adjusts the area to do the filtering and it will therefore keep the bumps over a further distance.

However, assuming that you are using raytracing, I would recommend to use a displacement map instead. The will not get filtered and if the displacement height is not to huge it should still give you a reasonable performance. Just make sure that your basemesh is not too coarse since this will slow down the displacement calculation.

Re: Texture filtering

Anonymous — Fri, 11 Jul 2014 15:40:38 GMT

Thanks Florian and Michael,

I don't have a problem in battling aliasing and noise with brute force sampling, I do have a problem when my nice rough surface becomes shiny, I can't fix that with higher sampling 😞

The setRaytracingStillFrameTextureSharpness looks interesting, and the tip about displacement too! Let's just hope my RAM can take it... But that would get me bump self-shadowing as well which is cool.

I'm off on vacation, so I won't be able to try this for a few weeks, but thanks a lot for the quick awesome help!

Jens

Re: Texture filtering

michael_nikelsky — Fri, 11 Jul 2014 16:17:16 GMT

Displacement mapping in VRED doesn´t require much RAM. Basicly the accelleration structure gets a littlebit deeper and your texture will be RGB with mipmaps, that´s pretty much it. We don´t create any triangles so you can pretty much put it on everything and won´t get into any trouble memory wise. Only thing to keep in mind is, since we don´t create triangles, the base mesh shouldn´t be too coarse, otherwise the rendering will take much longer. But if you have car with a good tessellation you should be able to just apply a displacement map to everything and be fine.

Re: Texture filtering

Anonymous — Mon, 11 Aug 2014 06:35:26 GMT

setRaytracingStillFrameTextureSharpness together with setRaytracingInteractiveTextureSharpness did wonders for me, thanks!

Displacement mapping also seems to work great, although I'm a bit surprised that it does, as you seemed to mention that the lookup is mipmapped, which is texture filtering in my book. I'll have to experiment more with it though, it looked awesome.

Re: Texture filtering

michael_nikelsky — Mon, 11 Aug 2014 06:55:03 GMT

Hi,

good to hear 🙂

Displacement mapping only uses bilinear filtering, not mipmapping. The mipmap levels are for some internal precalculations we need to do to accellerate the displacement mapping.

Kind regards

Michael