Author Topic: [RESOLVED] Curvature Node Issues  (Read 2057 times)

0 Members and 1 Guest are viewing this topic.

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
[RESOLVED] Curvature Node Issues
« on: September 25, 2017, 03:17:46 pm »
In the attached image you can see the result of applying a considerable amount of contrast (color adjust) to a curvature node output. The consequence is a darker curvature (edge mask), but also the outline of the polygons that constitute the mesh surface. This is an undesirable effect, which can be mitigated somewhat by using an occlusion node and inverting the color.

There needs to be a "push off" modifier to prevent the curvature from being detected at .0001 off the surface of the mesh. Does such a thing exist in Keyshot?

« Last Edit: September 30, 2017, 03:10:41 am by cjwidd »

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
Re: Curvature Node Issues
« Reply #1 on: September 29, 2017, 03:54:57 pm »
I feel like this is a fairly serious drawback if this feature is indeed behaving as expected. Could I get some clarification on the matter, please?
« Last Edit: September 29, 2017, 05:55:41 pm by cjwidd »

Offline Esben Oxholm

  • KeyShot Beta
  • Hero Member
  • *****
  • Posts: 1670
  • esbenoxholm.dk/keyshot-video-course
    • Freelance CG Artist
Re: Curvature Node Issues
« Reply #2 on: September 30, 2017, 12:14:39 am »
Try to use the 'color to number' node to adjust the contrast of your curvature texture instead of the 'color adjust'. Should give you more precise control of what you want to stand out.

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
Re: Curvature Node Issues
« Reply #3 on: September 30, 2017, 01:13:22 am »
I appreciate the advice and I gave this a try. Ufortunately this does not improve the situation. I think this is a more fundamental issue pertaining to how Keyshot is calculating the curvature. It's not doing anything wrong, it's just too sensitive; of course, for a NURBS model, this is not so much of an issue.

Offline DriesV

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 2412
  • Product Specialist at Luxion
Re: Curvature Node Issues
« Reply #4 on: September 30, 2017, 01:26:45 am »
I am a bit confused when you say "applying a considerable amount of contrast (color adjust) to a curvature node output". All I am seeing in the screenshot is a Curvature node connected to Color Invert, with a preview of just the Curvature texture?

The Cutoff and Radius parameters in the CUrvature texture can be used to control the "extent" of the curvature.

This is the first time ever that I see the curvature texture "catching" individual polygon edges.
Juding from the mesh topology, this looks like a scanned model, correct? If so, then maybe the polygons are not connected smoothly?

It would be great if you could share the model (publicly or through PM), or at least with support. :)

Dries
« Last Edit: September 30, 2017, 01:28:16 am by DriesV »

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
Re: Curvature Node Issues
« Reply #5 on: September 30, 2017, 02:00:30 am »
Good suggestion, I have attached the mesh below. The most straightforward solution is to retopo the mesh, but in this case, I would prefer to not do that. This object is a piece of a NURBS model that has been imported into Zbrush and then dynameshed. If you're not familiar with Dynamesh in Zbrush, it basically projects polygons onto a surface to create a uniform canvas of polygons to sculpt on. The result is, in some cases, millions of polys, depending on the mesh complexity, etc.

EDIT: Yes, smoothing (and topology in general) is probably an issue, but I suppose it depends on the renderer.
« Last Edit: September 30, 2017, 02:22:55 am by cjwidd »

Offline DriesV

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 2412
  • Product Specialist at Luxion
Re: Curvature Node Issues
« Reply #6 on: September 30, 2017, 02:33:00 am »
Thanks, I will test some Curvature setups.

The mesh does look pretty crappy though. No offence :).
Just applying a Metal material, reveals a pretty bumpy surface.

Dries

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
Re: Curvature Node Issues
« Reply #7 on: September 30, 2017, 02:42:21 am »
SurfaceGotBump lol

EDIT: Right, so the mesh you are handling is a decimated version of a high poly dynamesh model (+5 million)(see attached). However, even using the polished (smooth) high poly version, you may encounter a similar problem (see attached).

« Last Edit: September 30, 2017, 03:02:24 am by cjwidd »

Offline DriesV

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 2412
  • Product Specialist at Luxion
Re: Curvature Node Issues
« Reply #8 on: September 30, 2017, 03:05:53 am »
I think this can be solved by adjusting the Cutoff and Radius in the Curvature texture.
Attached is my attempt using your model. I think it works pretty well.

Dries

Offline cjwidd

  • Sr. Member
  • ****
  • Posts: 269
    • ArtStation
Re: Curvature Node Issues
« Reply #9 on: September 30, 2017, 03:10:29 am »
I think it works pretty well.

Hmm, yeah man it looks good. Well done. I guess there is some give and take with respect to blur / sharpness and the masked edges, but you struck a good balance. Thanks for the input, really appreciate it.