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Displace issue or bug

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Displace issue or bug

Unread postby ambassador1 » Fri Sep 14, 2018 11:47 pm

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 23 times
defA2.jpg
single map
defA2.jpg (10.95 KiB) Viewed 649 times
defA.jpg
error after blending maps
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Re: Displace issue or bug

Unread postby mdkai » Sun Sep 16, 2018 10:09 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
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deformerBug_02.zip
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Re: Displace issue or bug

Unread postby ambassador1 » Mon Sep 17, 2018 6:37 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 9:06 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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Re: Displace issue or bug

Unread postby gjennings » Fri Sep 21, 2018 9:42 am

Hi!

Took a quick look and your 8bit map "output Layer" attribute is set to "all". If you keep it to the default "rgba" things seem to work without the need to adda reorder node on the 24bits map.

We still need to investigate why switching to "all" produces this kind of behavior though - more news soon !

Cheers,
Greg
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Re: Displace issue or bug

Unread postby ambassador1 » Fri Sep 21, 2018 6:00 pm

gjennings wrote:Hi!

Took a quick look and your 8bit map "output Layer" attribute is set to "all". If you keep it to the default "rgba" things seem to work without the need to adda reorder node on the 24bits map.

We still need to investigate why switching to "all" produces this kind of behavior though - more news soon !

Cheers,
Greg


Yes, depending on our source of disp map, polliigon.com, mega, etc, we have to set the attribute to all for the map to have any effect. Again, depending on the source, rgba will result in zero effect. what would be the correct attr for grey scale, I would have thought something like r, or rrr, but that does not work.
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Re: Displace issue or bug

Unread postby dboude » Mon Sep 24, 2018 9:12 am

Hi,

Something goes wrong with greyscale textures. Normally if you import a greyscale texture and plug it to a reorder set to aaaa you can see your greyscale. (the only channel in a greyscale texture is considered as an Alpha)

I added an entry in the bug tracker.

For now, you have to :
- set your map file to force luminance
- or set the output layer attribute to all and plug the map file to a reorder set to rrrr.


Cheers !
Démian
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