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Re: Please rollback the Displacement node back to old version

PostPosted: Thu Mar 28, 2019 7:17 pm
by ChrisH
grimm wrote:I just did a quick test with 16.3.3 and didn't have any issues. These are the steps I followed:

1 - created a plane
2 - went to top view (7)
3 - UV unwrapped with project from view
4 - Pack islands (to make sure that the UVs exactly match the image)
5 - Added an array modifier to test tiling
6 - Set up the nodes and rendered in the preview (I set the displacement texture size to 4096x4096)

I'm thinking that either your UVs are not exactly on the image borders or there are some artifacts in your displacement images?


So, I'm 99.9999% sure that the borders of the UV are right on the edge (Doing a simple UV unwrap of a single face plane will do that, as will Project from View (Bounds) do). I even tried UV unwrapping the way you described*, but with the same result.
I can also look at the edge of the plane with just the texture in the diffuse channel (no Displacement) and see that the texture fits perfectly (no weird lines etc).

What I think differs from our test (to yours) is that you used a tileable texture (right!?). Tileable textures is not a problem, since the repeated edge ([0,0] to [0,1]) matches perfectly to the "last edge" ([1,0] to [1,1]), and thus if it goes a pixel or so over, it makes no difference.
If the texture isn't tileable (like from the World map generator) the issues appears (since the edges doesn't match).

As seen in my screenshots, there's bleed over if there's no displacement (and UVs are right on the image edge [or 1px inset]). I used those colors (via a Gradient node, the OG texture is greyscale, loaded into a float image texture) to add some contrast (so we can see if there's some "bleed").
Octane_Displacement_7edt.png


(*Your approach actually made the UV edges like 1px inset from the actual image border)


(ETA: I've added my test .blend, plus a screenshot of the UV scaled slightly bigger than the image)

Re: Please rollback the Displacement node back to old version

PostPosted: Thu Mar 28, 2019 7:40 pm
by grimm
Do you have the blur filter turned on? I can see some of these artifacts when I turn it on, but looks good when turned off.

Re: Please rollback the Displacement node back to old version

PostPosted: Thu Mar 28, 2019 8:16 pm
by ChrisH
grimm wrote:Do you have the blur filter turned on? I can see some of these artifacts when I turn it on, but looks good when turned off.


The filter is set to None in the tests, but I tried it with the radius from 0 to 15 (and all the resolutions), and these "edge artifacts" are still there.

Re: Please rollback the Displacement node back to old version

PostPosted: Thu Mar 28, 2019 9:39 pm
by grimm
Hmm, not sure then what the issue is? I have tried both tiled and non-tiled displacement maps, 8-bit and 16-bit versions, simple and view projected UV unwrapping, and still do not have those artifacts. The only time I can see some problems is when I turn on the filter. Could it be an OS issue, I'm running Linux Mint 19?

Jason

Re: Please rollback the Displacement node back to old version

PostPosted: Thu Mar 28, 2019 9:56 pm
by grimm
Just wanted to add, if anyone has a displacement map they would like me to test, I wouldn't have any problems testing it.

Re: Please rollback the Displacement node back to old version

PostPosted: Fri Mar 29, 2019 2:48 pm
by ChrisH
grimm wrote:Just wanted to add, if anyone has a displacement map they would like me to test, I wouldn't have any problems testing it.


You're welcome to download my test scene (above), the texture is packed into the file. :)

Re: Please rollback the Displacement node back to old version

PostPosted: Fri Mar 29, 2019 5:56 pm
by grimm
ChrisH wrote:You're welcome to download my test scene (above), the texture is packed into the file. :)


Yarrg! I didn't even notice that, downloading it and checking it out. :D I definitely see the issue now, it looks like Octane is going past the edge or wrapping the edges around? I double checked my displacement tests and can see some of the same issues, they are just harder to see. I also brought your image into Krita and took a look at it. I didn't see anything wrong with it, although Krita did load it as a 8-bit image. I converted it to 16-bit, but it didn't make any difference. Looks like a bug to me.

Re: Please rollback the Displacement node back to old version

PostPosted: Fri Mar 29, 2019 7:07 pm
by milanm
There is one more filter.

The artifacts are caused by bilinear interpolation between pixels on the opposite edges of the texture because it's being tiled. And tiling can not be disabled (currently).

Notice the gray edges:

ImageImage
Here is the 5x5 pixel map.
5x5.zip
(1011 Bytes) Downloaded 14 times

There was a big discussion about this in the C4D forum too.

I hope this makes sense.

Regards
Milan