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Displace issue or bug

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Displace issue or bug

Unread postby ambassador1 » Sat Sep 15, 2018 12:47 am

I am getting an odd error when I setup a simple scene, clarisse polygrid, with displacement, and two map files blending into each other for the displace. On their own, the maps apply as expected, but when going through a blend, the displace terminates oddly at each poly edge. See simple scene for example. The polygrid has 10*10 spans, you can see the errors at each span. Linux, 3.6sp3

Any thoughts?
Attachments
deformerBug.zip
(78.27 KiB) Downloaded 2 times
defA2.jpg
single map
defA2.jpg (10.95 KiB) Viewed 121 times
defA.jpg
error after blending maps
ambassador1
 
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Re: Displace issue or bug

Unread postby mdkai » Sun Sep 16, 2018 11:09 pm

Mixing two maps of differernt bit depth is causing this, map 1 is a single channel 8bit jpg, the second map a 24bit jpg.

I guess its blending channels that are not existing, with existing ones may result in that bug.
Simply plug in a reorder node and set only a single channel for map_file_B to fix the problem, but i did for both.
displace.PNG


Other tips:
- avoid 8bit jpgs for displacement general, the terracing effect will show
- avoid extrem scaling, because the values will offset, your scene displacement is set to 80 cm yet the displacement is about 90 m high, because the plane is scale by 417. Also scene bounds are very large.
Adjust the plane size to 417 and a proper scale value and bound will help speed up in larger, more complex scenes.

Cheers
Kai
Attachments
deformerBug_02.zip
(78.64 KiB) Downloaded 1 time
mdkai
 
Posts: 115
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Re: Displace issue or bug

Unread postby ambassador1 » Mon Sep 17, 2018 7:37 pm

jpgs were for the upload limit here, debug scene, we do not use 8bit for displace in final scenes. We do often mix displace maps from different sources, so well have to keep an eye out for that, thanks for the info! Haven't ran into it for years, so not that common. Also, never ran into the issue in other engines when mixing disp maps, e.g. prman, arnold, mr, modo.

The scaling is not extreme, Clarisse needs to be able to handle extremes, that's why we use it :)
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Re: Displace issue or bug

Unread postby mdkai » Mon Sep 17, 2018 10:06 pm

Sure no problem, the upload limit is fairly low, indeed.

I think Clarisse is strict on how to mix channels because values are always treated as vector data, so anything + NAN may cause an issue.

Maybe this error is something the dev team may look into for some error/feedback checking ?

The scale thing is just a numbers thing, since scale will also scale real world values off, if the displacement is set to 80cm but is actually 800m ... not that it is totally wrong but it adds up for possible problems, which can be avoided, but as long as you are fine with it ;)
Im not against a flexible workflow, but i prefer clean scenes over messy ones, and im quite nagging on these things on my team :roll:

Cheers
Kai
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