My displacement problem

[sampakinpa]

Hi there,
I set up an octane diffuse material with an 8K displacement map I generated in zBrush. the character body displaces fine but the hand/feet fingers are messed up. in mental-Ray this setup renders successfully with no artifacts. What am I doing wrong here?
Working on OctaneRender for Maya 2.20 - 6.1.

examples and setup:

Please help.

[prodviz]

The only help I can offer, is that people say a 32bit file is needed.

I'm really interested to see how you get on with this, because I had a very similar issue (from mudbx). Unfortunately I couldn't solve this in the time, but as I was working on a still image, I took the file in to zbrush and decimated the model to a level which was workable.

I've asked for a tutorial from either mudbox or zbrush a few times, but to no avail.

Good luck and let us know if you crack (no pun intended) this one.

Oh, and here's a list of notes from one of the developers:

Displacement Mapping

1) If using a Displacement map, remove any Bump or Normal maps.
2) If you use a Displacement "Amount" of 0, the object will not render
3) Octane assumes black pixels in the displacement map have 0 displacement. If using a displacement map where 0 is a negative displacement (for example, a map generated from ZBrush), put a "Shift" of negative half the "Amount" (ie. if the Amount is 0.01, the Shift will be -0.005)
4) Large polygons with displacement will render artifacts if the displacement Amount is small.
5) Displacement mapping requires UV Projection surfaces. It requires a displacement texturemap, and procedural textures and Octane nodes which modify the displacement texturemap will be ignored. Similarly, the Displacement Texture Greyscale Image "Power", "Gamma" and "Invert" pins are ignored
6) Very large displacement "Amount" values may position vertices in an invalid position which may crash Octane. So start with small (0.001) Amount values and increase from there.

[sampakinpa]

Thanks for the notes and for your fast reply prodviz.
I'm using a 32bit EXR file for the displace map and I'm doing the negative shift in the amount.
Maybe JimStar will have a clue to what is going on here. Displacement is a crucial feature with my work and I'm sure of others.
If someone experienced the same artifacts please let us know.

[sampakinpa]

After some experimenting I noticed that when the poly object is hard edged, there are no artifacts when displaced. the artifacts occur only when I introduce edge normal smoothing...

displace with with no normal smoothing.

displace with with 30 degree normal smoothing.

wireframe render - displace with with no normal smoothing.

wireframe render - displace with with 30 degree normal smoothing.

wireframe render - no displacement

[prodviz]

Interesting find.

In general, I'm still not convinced about using the negative Shift value.
This is a total guess, but I reckon this is the issue with most of everyones displacement issues , as all the tests I've done without the negative value are fine.

The issue seems to be the displacement file from the sculpting packages has a black value for negative.

[sampakinpa]

Zbrush displacement export setting:
-16 bit map!
-mid value = 0, to eliminate the use of negative shift in the amount.

it seems that the 16 bit map is the main issue here. all experiments with 32 bit map failed!
With the 16 bit map, all artifact were cleaned out:

[prodviz]

Awesome, cheers for the info.

Out of interest, are the mentalray and Octane renders looking the same?

cheers.

[sampakinpa]

Yes, looks the same but it seems that octane renders faster.

[prodviz]

Great stuff, cheers again for the info.

[linvanchene]

Thank you for this information!

Can anyone share a screenshot of the map preview inside the displacement slot of OctaneRender with settings that worked?

I am curious how a displacement map with fine details for characters should look like to work in OctaneRender.