Problems with Vray RTT (Render To Texture) in the Vray 1.5/Max 2008 combo.

[harry101]

Hi

I work with Quest3D making virtual presentations and I would like to use Vray to make Lightmaps in 3D Studio Max. I had a long time finding answers on what to do and I get it right sometimes and other times everything falls apart. If anyone have a false safe route through this I would be very grateful. Here is what I do !

3D Studio Max 2008 an Vray 1.5.
- Scene with some "channel 1" UVW mapped and textured objects and a Vray light. I make sure that the light is stored with irradiance map and that the GI is on.

- I render the scene to see if the shadows, that I am after, looks right.

- I open RTT dialog. Make a Path for output and make sure my object are selected and listed in the "Objects to bake" rollout.

- I check "Use Automatic Unwrap" with Channel 2.

- I click on the "Add.." button in the "Output" rollout and select "VrayTotalLightningMap". I have tried all of the Vray "texture elements" but it is only the lightning maps that gives me what I want. (I thought that one of the shadowmaps would be correct, but here I gets nothing).

- When I see that the map is "enable" with a name, file type (jpg or tga), and I set "Target map slot" to Diffuse Color.

- I then adjust size to a factor of two (256 x 256, 512 x 512 and so on)

- In the "Baked Material" rollout I would like to have a separated image with the light and shadow information and I select "Save Source"/"Create new baked"/"Standard:Blinn".

- I click "Render"

- Sometimes I get what I want. A clean shadow light image that I can blend over the texture in Quest3D. Most of the times I also get the texture, where shadow and light is baked into the finished image. This I don't want.

- Some other times it will not render out in the right size (256 x 256 and so on), but I get a 648 x 480 image. Even if the normal render output is something else.

- Other times I get a croped version of the image.

What I want is a texture image with just the shadow and light informasjon and nothing else. If I never got this I would think that I did something basicalley wrong, but when I get different results from the same scene with the same settings I am not sure what is wrong.

Does anyone have a false proof methode to make a light/shadowmap in Vray/Max 2008. I don't need any alpha information, just the greyscale shadow and light texture image.

Thank you!

Harald

[vlado]

Do you use any standard materials in your scene? There is a difference in how standard and VRayMtl materials appear in lighting elements. Usually it is better to stick to VRayMtl materials (there is a conversion script for this).

The other issues (changing resolution and cropped images) are not related to V-Ray though, as they are supplied by 3ds Max to the current render engine, whatever it is at the moment, meaning that V-Ray just uses whatever data is passed along from 3ds Max.

Best regards,
Vlado

[harry101]

Thanks for your answer Vlado. I guessed that the problems with the resoulution and cropping of the RTT images would be a fault of 3D Studio, or the combo with Vray, but the biggest problem is that I can't use Vray materials in Quest3D, just standard textures.

The idea is to use a small tileable texture as the basic material on a object and then use Vray lightningmaps on top, where the shadows is in a nuance of grey and where I can knock/blend the white out of the lightmap. A solution is to build my scene in Max and then export everything to Quest3D before I make a Vray version where every objects is white and then make the light/shadowmaps from this scene. It works !

Thanks

BR

Harald