Cineversity

Im having trouble with a displacement map I made in zbrush and am using in arnold for c4d. Ive tried the same map in vray and it works fine as you can see in the first image. The second image is the result arnold is giving, it kind of bloats around the edge. There geometry is quite a thin piece so its not the easiest thing but if vray is managing it I can’t see what arnold isn’t. Has anyone come across this? Also if anyone knows of a dedicated arnold forum please let me know. Thanks in advance.

Hi HA UK,

My first step was to Goggle the problem, but my impression is, there is not a vast amount of problems. This is often my first step, checking how often this is found, to get an idea about.

Then I checked the manual:
https://support.solidangle.com/display/AFCUG/Displacement

Since Cinema 4D seems here more the hub in the workflow than it might be difficult for me to answer, based on two result images, not even knowing a single bit of the underlaying set up.

First of all, I encourage 16bit/channel textures for this work, anything 8bit/channel seems rather useless for high quality work. The Arnold manual highly suggest, as I do, to use floating point formats for this work, they expect trouble by not doing so. My favorite format is OpenEXR, which is also an industry standard. To save space on a disk by using anything else is not advised!

The image need a nice density/resolution.
The file needs to be know how the information is stored, in gray values [intensity/centered, red green, or RGB in different ways]

Is the artifact with all material channel settings available, or does it change, is the artifact even available with a blurred texture.

My best guess [sorry about, guessing is not my favorite thing] would be to turn the subdivision iteration down, this will hope full show some results.

Typically, problem solving is one parameter at the time, other wise you get no solid feedback. An inspection of the texture map and a comparison with one that worked might help as well.

I’m not aware of a forum, as I can’t buy all the 3rd party render available for Cinema 4D and it is nearly impossible to keep up with their often nice progress.

I would ask the support from Arnold about the best user forum, they normally know great resources of course.

My best wishes.

Hey. Thanks for answering. With the images I showed I’m already using 32bit exr and even cranked the image up to 8192, the highest zbrush can go, just to make sure. I have now managed to improve it quite a bit by playing with the displacement scale and height settings but there is still a line there. Granted I’m being picky but I always like to aim to get the best possible result. Potentially its just a very difficult set of circumstances for displacement. I’ll keep trying but I can live with it how it is.

Hi HA UK,

Great that you use already the best possible! That eliminates already a core element in the search.

I think you should be picky and shoot for the quality you like to have. Since you get good results with other render-engines, you should certainly contact the Arnold support. I consider such contact as well as a help to avoid this problem for others. So, don’t hesitate.

Perhaps gather some data before you ask.

• Is this phenomenon as well there when you use a complete, e.g.,  0.18 [50%] gray value?
• Does it show up with a pre-subdivided Mesh?
• Can you re-produce it with different light angles?
• Is the color profile set to linear?
• How does this respond to reflections on the surface?
• Are all polygon-normals in the same direction?
• Does the texture produce the same artifacts on a fresh Plane object [made editable]?

This information might accelerate the solving process, but I can’t speak for the developer of this 3rd party product. Arnold has certainly its reputation and I wonder that this problem shows up at all.

My best wishes