Problem with clean displacement

[RolandB]

Hi

I've tried an exercise with some displacement map and it seems that I have some problems with the renders.
I looked at a solution here but with 4 pages about displacement and some solved problems I didn't find mine.

I try to make some clean edges displacement but here is the result I always have.
The map is a clean grayscale TIFF, saved in 32bits format (tried in 8bits, the same result).
I've lowered the level of the map's blur to 0,01, and filtering to none (same results with blur to 1.0 and filtering to default)
Do you have any solution ?

Thanks a lot
Roland

[RolandB]

Sorry for the error of category... it's not -for the moment- a solved bug.
i forgot to tell that I tried with a tesselate (4 iterations) modifier : it's a little better but the not perfect yet...

[johan belmans]

Hi Roland,

why don't you model this? It does not look that complicated.
I do not think you will get cleaner results. But I am not that kind of PRO displacement guy.
Or am I missing something?

[RolandB]

hi Belly
Yes i can model it of course, but it was a question we ask on a Vray forum, and I wanted to make the same result as this (with VRay therefore) with Corona.
Need to have clean edges but also sheet metal like above on the image... and no, you didn't missed something ;)

[RolandB]

Thanks to Romullus and sorry for the wrong category...
Any answer about my question ?

[maru]

If you want your final effect to look like this https://forum.corona-renderer.com/index.php?action=dlattach;topic=5967.0;attach=24227;image then you should use a different map for displacement. The one you are using in your pictures from Corona has no transition between black and white so the edges are rough . Your Vray rendering (the one I linked above) has displacement with less steep edges. It would require additional blurring. You can achieve this procedurally by using gradient ramp map. Maybe Vray uses filtering/blurring for displacement maps automatically? Or am I missing something?

[johan belmans]

When I saw your image in post #3 I was thinking the same as Maru.
I am nothing missing anymore ;-)

[romullus]

When there's extremely sharp transition between different height values, micropolygon displacement will struggle in most renderers. In such situation displace modifier can be vastly superior. Look for yourself:

[RolandB]

Waooooo !!! Amazing result Romullus ! And as I look you did the video specially for the topic ! Thanks a lot ! I'm really happy with this amazing solution ! Thanks again, I will post my result tomorrow.
Roland

[johan belmans]

Great tutorial Romullus!!

[romullus]

Glad that you find it useful, though it's not tutorial at all - for me it's much easier to show something in video than trying to explain in english :]
One thing that i like about displace modifier, that unlike micropolygon displacement, it obeys texmap filtering settings, which can be very handy sometimes.

[Ludvik Koutny]

MTD can work well actually. It's just that Corona's implementation is not that good yet. Vray tessellates the geometry according to the bitmap, and then displaces it. While corona first tessellates randomly, and then displaces that random web.

[RolandB]

Your explanation in all cases Romullus was super helpful because cutting a plane in countless faces is not a solution (4 million in your example, and an imperfect result is not viable).
This is in any case a first test, very clean and conclusive!
thank you again
Roland

[romullus]

Actually it was more like 40 millions :]

MTD can work well actually. It's just that Corona's implementation is not that good yet. Vray tessellates the geometry according to the bitmap, and then displaces it. While corona first tessellates randomly, and then displaces that random web.

I don't have vray, so i can't compare, but mental ray isn't much better with displacement. OTOH i've seen pretty spectacular displacement in C4D in combination with SVG maps.

And of course, it'd be very nice to see improvement in Corona's displacement in future.

[RolandB]

Yes I was wrong... but 4 or 40 millions is too much for a simple plane !