Cineversity

Hi There,

Last week I started on a project using hair driven by various texture maps for density/length/kink/fizz etc. and I’m running into an annoying issue.
If you look at the image you can see that it creates clusters of hairs for some reason near the guides, rather than spreading the hairs out “evenly”.

Cinema4D R21
Distribution = Polygon Area
Cloning = Off
Density is controlled by a greyscale texture from MARI (linear) and levels are 8.

I’ve fiddled with pretty much all settings but none seem to want to spread out the hairs more evenly.

Also I did try the “minimum spacing” but this just reduces the number of hairs in a cluster while vastly increasing the render times so it’s no option really.

Anyone got experience with this?

Hi PeekCS,

I have sent you an upload link. I can’t tell from an image, nor do we have had that problem here in the forum before.

https://help.maxon.net/us/index.html#OHAIR-HAIRSTYLE_GROUP_HAIRS

All the best

Hi there,

I’ve sent the files over so you can have a look.

Cheers!

Thanks for the file, PeekCS.

I can’t have a full look at it, as I do not run Corona here.

In Standard render, I was not able to get any usable results here. So I copied the whole content and opened it in a new file. Some change was noticeable. I assume something has compromised your file. Besides, I do not used the Hair Tag on the Polygon model, this seemed to be one of the problems.

The next step was to animate the hair Channels in the material. This meant with the progress of the time-slider, I got less and less influence from the material. I could not see or reproduce the problem.

Next step, calling up a new Hair Object. Which worked fine. I applied the textures and the settings from your Hair material and checked each step with a render. In the new file I can get the same results for both.

I consider that the Clump texture was missing as a minor problem.

I rendered each state and compared it, hence why my reply took a while.

Please have a look at the file, I have sent you a link. I think that should work.
Since it was marked private, I sadly can’t share it here.

Cheers

Thanks a lot for having a look at it and I understand about Corona. Thing is, since this will be a “film” quality model, working with UDIM’s for the textures is pre-requisite and C4D does not natively support UDIM’s yet (which is weird since it’s a texturing standard nowadays). Using a standard Cinema hair object with a Corona Bitmap on UDIM settings crashes.

At the moment there is no clump texture yet, I simply plug in the Frizz in that slot, it’s still a WIP after all

Indeed the distribution in your scene is what I’d expect from the “polygon area”, so perhaps I will need to create a new scene myself with a fresh tag, as I can not use the standard Cinema hair object for this project.

Since I tried nearly all settings I am still curious what causes this issue and if it’s something that I set wrong, rather then a bug.

Thanks a lot for your help, it is pointing strongly in the direction of a bug at the moment although it might be a bug in the corona hair object specifically. Did also post this specific problem on their forums but haven’t received a reply there yet.

Cheers,

Hi PeekCS,

The central part here might be a discussion of problem analysis.
One technique is the binary elimination procedure. Taking half of the influences away. (…here, for example, the impact of the textures). Then render and have a look. If the problem persists, the other half might produce the problem. So, we take half of those out (a quarter by then). With this, we usually get in a few steps a problem location. Of course, it can be a problem that only occurs when all influences work at the same time. However, it will become quickly apparent.

The other is a replacement tactic. To use different textures, with a single color, for example, or none at all. Perhaps we exchange the whole model and start with a sphere, to create this setup.

I think it is fair to say while talking about movie production standards, that the pipeline is tested with simplified objects first. Then with some more complex, project-related setups, before any full production takes place. Along these tests, any of the problem-solving strategies can take place.

UDIM is for nearly two decades in existence, but its integration is undoubtedly very strong in the Foundry collection of applications, thanks to WETA.
Yes, if you need UDIM as a core technology for your workflow, or perhaps PTex, as well as Atlases, you should make a suggestion then.
https://www.maxon.net/en/support-center
If no one asks about this, chances are high that the development resources focus on requests for other features first.

All the best

I did indeed put in that request quite a while ago but I’ve just created another request for it. As well as a request for being able to select, view and edit UV’s on multiple objects at the same time which is a rather rudimentary feature which still seems to be missing up until today (you have to combine all your meshes into one, do the UV’s and then split them again at the moment).

This project is a test for the pipeline and at the moment it’s still a simplified object, so any issues I run into are part of the test. At the moment I’m plugging in the textures one at a time to see where it goes wrong but needless to say for this project, UDIM textures are a rudimentary requirement otherwise you can not get enough resolution in to make the textures. Working in anything over 4K is progressively more inefficient memory and performance wise.
At the moment the asset has 4 4K textures for each channel (COL/DISP/NORM/SPECR and various hair maps for styling).

I’ve worked on many film assets in the past as I used to work for 3 of the major VFX studios in London, but at my current studio (small one) they use Cinema4D instead of 3Dsmax/Maya so I’m trying to implement the standards that I’m used to in a pipeline with different software.
Needless to say there are various issues where C4D seems to be left behind a bit in terms of functionality compared to other major 3D packages.

Will get there eventually though, just have to find the correct workarounds for all the odd problems that appear, like this one.

Cheers,

Hi PeekCS,

Thanks for sharing. Always nice to get some more background.

So far, my impression is (over a few decades), most people are quite happy when UV work is not on their schedule.

Thanks as well for the suggestion.

Cheers