2D 3D displacement maps with Vray

[Adam H. Stewart]

http://h1.ripway.com/Adam_Stewart/Ba...2D_mapping.jpg
http://h1.ripway.com/Adam_Stewart/Ba...3D_mapping.jpg
http://h1.ripway.com/Adam_Stewart/Ba...ap_Optimiz.jpg

The three images above where all created using the same Zbrush displacement map. As you can see there is crazy stepping in the image created using 3D displacement. I have hunted around the Zbrush website where it appears this has been a problem for some time. They traced the problem back to the 3dsmax filter and blur settings. The 3rd image was the best result I could get using these settings. As you can see it is better then the straight 3D displacement but the image is not a patch on the smoothness of the 2D displacment. The reason I want to use 3D displacement it the success I had with it in my last project. It brought the render times down by almost 40 minutes a frame and looked better then the 2D.

Thanks as always for any help you can give me.

[RErender]

Are you using the VrayBmpFilter to load the displacement map?

[priad]

Pretty interesting test, thanks for sharing.

[Morbid Angel]

adam, this error effect is called banding and its quite common. you need to work with 3ds max bitmap blur filter. By default its set to 1.0 but you need to set it to 0.01 the banding will be removed.

[tom schuelke]

i think the vrBmpfilter, vlado wrote was adressed directly to the need of this issue.

using zbrush with 3d displacemant seems to work with this thing...


Tom

[panthon]

The 0.01 blur thingy does the trick. I don´t see the need for vraybmpfilter as it´s lacking some of the features a common bitmap dialog has. I don´t know if there´s any speed difference using each one of these methods, though.

[Adam H. Stewart]

More tests - but no Cigar

http://h1.ripway.com/Adam_Stewart/Ba...D_Blur_.01.jpg
http://h1.ripway.com/Adam_Stewart/Ba...rayBmpFilt.jpg

I'm not going crazy honest. I had to do another test to make sure even with the the Blur set to .01 and offset to 0 there is still noise that is not evident in the 2D displacement - look closely at the highlights and you will see it, it looks like the specular values of the material are being affected.

I am not sure what the VrayBmpFilter this is supposed to do, but I have tried it before and always gotten similar wacky results. Maybe it is as it says a Bump filter and not a Displacement filter. This test was done with the default settings but I have played around with them and they don't seem to change the bizaar results.

The time saving even with these simple images is quite substantial - 2D - 52.9sec - 3D - 27.8sec. Maybe it is because the 2D displacement has another level of filtering that it takes longer and gives better results ?

Thanks as always for your help.

[Adam H. Stewart]

Could this be the Reason

Like the crazy cat woman in number 21 I am responding to myself. I found this in the Vray manual :

Note that with 3d mapping the displacement map's range of values must be within the 0.0-1.0 range (black to white). Values outside of this range will be clipped

Could this be causing the banding - the 16bit displacement map image coming from Zbrush is being clipped by the 3D displacement only ?

I don't really know enough about 16bit images to tell.

Thanks as always for your help.

[DaForce]

why not just convert it to a 8bit image in PS and see if it makes a difference. ( i doubt it tho)