Author Topic: Difference between old displacement and new displacement  (Read 1404 times)

2020-04-10, 14:53:29
Reply #15

agentdark45

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Just to follow up here, I recently completed a project with a very finely displaced rug - I ended up having to switch back to the regular displacement mode (1px) as I was getting some weird shading issues with the new 2.5D displacement.

There were some odd "vertical lines" that kept popping up along the length of the rug and would only disappear if A. I increased the scale of the displacement map (bigger/less "threads") or B. I switched to the regular displacement. Auto bump in both scenarios only affected the darkness of the rug (didn't fix the vertical line artefacts in 2.5D mode). I didn't save any images of the issue unfortunately as it was an active project with a tight deadline - I may be able to revisit it later.

There was a noticeable speedup using 2.5D and no visual difference (apart from the artefacting) so it would be great to get this resolved.
Vray who?

2020-04-10, 15:25:28
Reply #16

TomG

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Did the rug geometry have any long, thin polys on it by chance?

2020-04-10, 15:38:50
Reply #17

agentdark45

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Did the rug geometry have any long, thin polys on it by chance?

I've attached a crop of it (old displacement, 1px), it was fairly evenly subdivided, with supporting edge loops (all quads, uv unwrapped) and an opensubdiv applied on top.

The displacement map is a coronamix map of the edge lines of the colour pattern mixed with a circular noise map jpg (I think taken from one of the stock Corona carpet material displace slots).
Vray who?

2020-04-13, 15:31:41
Reply #18

maru

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Everything has already been said here, but just to confirm:
- Old displacement + autobump currently results in incorrect shading. Using new displacement with autobump is preferred, or old displacement without autobump.
- New displacement can sometimes cause artifacts if the original mesh is not subdivided enough (e.g. flat plane with no subdivisions at all), if it has long, thin polygons, or if it has chamfered edges.
- We are looking into all of these issues, and hopefully in V6 we will have improved 2.5D displacement, which would make the old displacement obsolete.