Vray and Zbrush

[Steve_Green]

Hi Vlado,

thanks I'll give that a go - wouldn't it give artifacts along UV seams though?

Thanks,

Steve

[gregpetch]

Arg... I've found the same problem. The only solution I've come accross is to use very low quality displacement and a normal/bump map for details(a poor solution because low quality displacement can result in similar artifacts). The free plugin Gnormal lets you use normal maps in the bump slot and works very well, but only works for max 5.......

[Zeddicus]

Quick FYI regarding gNormal: I believe there is now a beta version available for Max 6. Haven't tried it yet though.

[gregpetch]

Hey, Vlado was right! A little bit of blur offset (about 0.008 works for me) and summed area filtering works very well. Oh, and it's good to see that gnormal has been updated, especially useful if you need to blur the displacement map.
Though Steve_Green is right, blurring the displacement map will give you artifacts in UV seams.

[ihavenofish]

testing this yesterday i noticed i got banding on 3d mode, but none on 2d mode.

i have one theory that maybe vlado can answer and confirm or reject it. could max be clamping the map to 8 bit? a while back i was using simbiont and found out that it was clamping colours before rendertime(they have since fixed this). i wonder if vray, or max, might be doing the same? maybe there is a glitch somewhere in the 3d displace code clamping this? i get the same banding in mental ray.

any help would be appreciated

later

[trixian]

Didn't max's bitmap filtering (pyramidal/summoned area) use to clamp colour space earlier? Seem to remember that was a hdri loader issue, so maybe turning off filtering there would help? Unless its the filtering in the displacement modifier rollout thats the culprit.

[Steve_Green]

Could be - maybe its worth a try converting to something else like a 48bit PNG or HDRI or the Splutterfish OpenEXR plugin - I've just woken up and I've got to go to work in a sec, but I'll give it a try tonight.

- Steve

[samuel_bubat]

Hi there,

I made some tests in the past.
http://sorceress.netfrag.org/optix/displace_tests/
the picture 0 - 4 show the result when increasing the blur of the bitmap.
picture 5 shows a bitmap with a displace value of 10.
picture 6 shows a hdr with a value of 1.
pic 6 has a much better quality !!
maybe it´s worth playing with different blurs outside 3dsmax.

(the hdr was made of the bmp. Loaded into fusion, gained the colors
by a value of 10, added a little blur and saved as hdr)

Seems this guy seems to talk about the same problem.
http://www.chaoticdimension.com/foru...pic.php?t=6222

[losbellos]

for smooth result, the gaussian blur is the best. You can even make a stright slope with smooth linear surface. But I guess, that would also sacrifice detail.

[Steve_Green]

Just an update, Martin Kroll who was beta-testing Zbrush has said he's found banding in the release version which wasn't apparent in the beta. It seems to be a bug that shows up in some renderers but not others, and Pixologic are investigating...

Hopefully they'll get to the bottom of it.

- Steve

[Zeddicus]

Steve: Saw that post too. Got my fingers crossed!

[Zeddicus]

Think I solved the mystery of the banding, at least as far as Zbrush and Max are concerned. Seems to have something to do with the initial blur setting when loading a map into the material editor. More info in the official Zbrush forums for those interested.

http://www.pixolator.com/zbc-bin/ult...c&f=1&t=014729

[Steve_Green]

Hi,

I missed this post - turning the blur right down seems to work great.

Cheers,

Steve

[vlado]

I've been playing with a zbrush file today; it seems that the standard filtering in 3dsmax is very poorly suited for this task. I ended up writing a small plugin (which is part of VRay now) that maps a texture exactly, without any extra filtering, and in the way zbrush appears to expect; here is the result:



and the high-res version: http://www.vrayrender.com/stuff/zbrush_large.png

If someone of you is a registered VRay user who plays with zbrush a lot and would like to test this, you can drop me an email to vlado@chaossw.com.

Best regards,
Vlado

[Zeddicus]

Just posted about this on the ZB forums, so I won't repeat myself. Beautiful high-res render by the way!