Displacement for arch viz - a speed up observation and more

[Micha_cg]

Hi,

I the past I avoided to use displacement for exteriors, because it slow down the calculation to much. For example the light cache pass needs extreme much more time, but ... I found, that the LC can be fast precalculated without displacement, saved as cache file and during the later use with displacement no errors are visible (I used displacement for the grass of a bird view rendering)
Doe's somebody tested it too? Are known disadvantages for this method?

I ask me what is the best way to disable the displacement? I used the global displacement amount and set it to 0, maybe there is a better way.

Question for the Chaosgroup USA developer: if the disabled displacement works fine, could there be an option "disable displacement for LC" and the LC is automatic calculated without displacement?

Ciao,
Micha

[40th]

Re: Displacement for arch viz - a speed up observation and more

I know this situation since almost In all my models I use Displacement.
Good way IMHO is to set volume of 1 in the subdivisions in the global displacement menu.
It makes the render as if there's no displacement to render, which is great for test renders.

[Micha_cg]

Re: Displacement for arch viz - a speed up observation and more

Thank you for the hint.

Did somebody got the effect that the CPU usage is swinging around a low value like only 30% during the rendering?

[fpedrogo]

Re: Displacement for arch viz - a speed up observation and more

Why don't disable the displacement on the materials. I know is locally, but usually you don't have a lot of materials with displacement.

[Micha_cg]

Re: Displacement for arch viz - a speed up observation and more

I use three materials with displacement and so it's faster done per single global option.

I found, that subdiv 1 show a light displacement effect, so I stick at amount 0 now. But my current subdivs are quite low at 56.

My current complex scene at 3000x1600 is rendered in less than one hour at an i7920@3.6GHz. I suppose so without the trick only the LC pass would need this time.

[Micha_cg]

Re: Displacement for arch viz - a speed up observation and more

Why don't disable the displacement on the materials. ...

I did it know, that there was a problem ... today I disabled the displacement at a material and after a rendering the displacement setup was lost and can't be disabled again.

[fpedrogo]

Re: Displacement for arch viz - a speed up observation and more

I did it know, that there was a problem ... today I disabled the displacement at a material and after a rendering the displacement setup was lost and can't be disabled again.

Got it! This is not good. The displacement information should stay there. Then your workaround is good for now. We should fix this in the future.

[LeoBonilla]

Re: Displacement for arch viz - a speed up observation and more

Why don't disable the displacement on the materials. ...

I did it know, that there was a problem ... today I disabled the displacement at a material and after a rendering the displacement setup was lost and can't be disabled again.

a Duplicated material can work?

[Micha_cg]

Re: Displacement for arch viz - a speed up observation and more

yes, this should work.

[Micha_cg]

Now ASGvis is chaosgroup and maybe the ways are shorter between plugin and core development. So please could somebody answer my first request for a disabled displacement for the LC calculation. Today I tested my scene at the new beta plugin with same effect - if displacement is enabled, the LC pass is horrible slow, nearly no progress. If I disable displacement it works like expected, also if I save the LC pass and set it to read and enable displacement. Could be great to disable the displacement for the secondary engine at the material options.

[Micha_cg]

Additional to my last post here a simple test scene. Two ways are possible:

(a) set global displacement amount 1 and render the image - unacceptable extrem slow rendered LC pass

(b) set global displacement amount 0 and render the GI only, than render final pass with global displacement amount 1 - fast rendered image

The result will look nearly the same, like at the attached image, but the render times will be very different. In the past I calculated the LC at displacemnet 0 only, and used full displacement for IM and final pass. This should bring a stable result, so far I know from my last project. The key problem is the slow LC calculation for displacement here. I hope the core developer can tell more. Attached the simple Rhino scene.

PS: Happy new year to all here!

[Micha]

Now ASGvis is chaosgroup and maybe the ways are shorter between plugin and core development. So please could somebody answer my first request for a disabled displacement for the LC calculation. Today I tested my scene at the new beta plugin with same effect - if displacement is enabled, the LC pass is horrible slow, nearly no progress. If I disable displacement it works like expected, also if I save the LC pass and set it to read and enable displacement. Could be great to disable the displacement for the secondary engine at the material options.

I wrote this post more than 2 years before, the thread was started 3 years before. Also I found that the request was done by an other user last year.
http://forums.chaosgroup.com/showthr...e+displacement

Today I run in the problem again - after more than a half hour the LC pass was at 15%. The rendering can't be stopped, since it hangs in the calculation. So only it helps to kill Rhino and start again, but than with the workaround.

Is there no way to implement a "don't use displacement for Light cache" if several hundred percent of render time can be saved?

[skysurfer]

Micha your idea it's great!
+1 for me.
This could help very lot.

[fooprobe]

Yes please