[itai bachar]

Hey guys
Im having some difficulties with displacement,
It is either very slow, with pretesselated, or just hangs Maya, with on the fly.
Ive gone and tried really basic stuff, on a simple sphere, trying from very low\corase settings
and the same slowness acures.
Is it just me or displacement is very expensive in maxwell?...
thanks

[Mihai]

Pretesselated is in most cases much faster than on the fly since it simply subdivides the geo and sends to render. Maybe you got the two methods mixed up? If it hangs most probably you've set a too high subd level.

http://support.nextlimit.com/display/mx ... +component

Regarding your other question about UDIM textures and Maya, please post that in the Maya forum.

[itai bachar]

Hey Mihai
im using a simple sphere with on the fly, Maya takes a long time voxelizing and than it hangs
with a very noisy image, it is unusable as everything is stuck/slow.
with preteselated its ok with a sphere primitive, but when using a more complex model, it becomes very slow exporting/voxelizing with as little as 2-4 subdivides.
Also, seem not logical that displacement should be that slow.
I thought it might be a Fire limitation but when sent to render, it took a very long time exporting/preparing
before it started to render.

[Mihai]

What kind of subdivision are you using, flat or catmull/loop? It matters also the height you are using, try with a lower height first and increase it to check. What is your RAM usage during rendering, and how much RAM do you have installed?

[itai bachar]

What kind of subdivision are you using, flat or catmull/loop? It matters also the height you are using, try with a lower height first and increase it to check. What is your RAM usage during rendering, and how much RAM do you have installed?

simple sphere test:
flat method
height 0.5-2
subdivision level 2
render preteselated took 12 seconds for SL 8
on the fly 45 seconds(!) for SL 8
I tried no subdivision on the sphere, with maya subdiv, with maxwell subdiv, nothing helps,
on the fly simply doesn't work in FIRE right now.
When i tried to displace a more complex model than a sphere, the faster pretesselated was very slow,
beyond what i thought reasonable, and what im used to in Arnold for example.
the machine is a dual xeon e5 2680v2, 64GB memory.
when rendering the sphere without subdivision on the model maxwell took 850 MB ram,
with subdivision - 1.2 GB ram.
thanks

[Mihai]

By simply doesn't work (about on the fly in FIRE), you mean that it's too slow? On the fly is best for low height very detailed displacements which would not fit in your RAM. But if it fits into RAM, use pretesselated.

Also regarding render time, check what the overall noise level is because if you set a render to SL 20 for example but it looks noise free by SL 14 you have wasted a lot of render time. SL is not a "fixed" render time, Maxwell doesn't have to reach the SL you set in order for it to be considered finished. If you set a low SL and the render still looks too noisy, you can always resume the render. Regarding that complex model, do a test with/without displacement to the same SL to see the time difference.

http://support.nextlimit.com/display/mx ... in+Maxwell

Each new SL takes approximately x1.5 times as long to reach as the previous one. If it took 10 minutes to go from SL 4 to SL 5, it will take about 15 minutes to go from SL 5 to SL 6.

when rendering the sphere without subdivision on the model maxwell took 850 MB ram

For a simple sphere scene? At what resolution?

[itai bachar]

I mean it displays a very noisy image and than stands still, not progressing, like something is disturbing it.
Ive read the manual and really thought on the fly is what I need, but for now its stuck.
All the small detail is very important...
I understand the SL, vs render time, yes.
Ill do the tests tomorrow again, as you suggest.
the sphere is a maya primitive, i gave it 50x50 divisions, instead of the 20x20, so it will need less
displacement subdivision levels. (was i wrong here?)

[Mihai]

No, not really but I'm just curious why it takes 850MB when rendering a simple sphere. What resolution are you rendering at?

[itai bachar]

1080 x 1920

[Mihai]

And regarding your test with the more complex object - no displacement vs displacement, what's the difference in time to reach the same SL?

[itai bachar]

hi
i tested to sl 9 so it would be quick,

without displ:- 1 minute

with disp on 2 men:
pretesselating time - 1min
voxelation - 55 sec
render time - 1 min
= about 3 min

with disp on 2 men and tractor:
refining/pretesselating time - 3.40 min
preproc - 37sec
voxelation - 1.1 min
render time - 1.1 min
= about 6 min



i'm uploading the scene here, if you like to check:
https://www.dropbox.com/sh/wuprvi8j6xr3 ... uzXea?dl=0
(its part of a tutorial from DT, he uses on the fly but as i said my pc doesn't cooparate with that...)
thanks

[itai bachar]

1920 1080
sl 9
pretesselated
flat
edges and corners
subdivision level 2
maxwell subdivision level 2 loop on most polygons

[Mihai]

maxwell subdivision level 2 loop on most polygons

Oh, but I think that's the problem. Unfortunately the Pixar open subdiv is not very fast and not multithreaded as far as I know. Please try the subdivision only on the displacement component itself, you can remove the object modifier subdivision. Here you are first subdividing the initial geometry twice, then twice again with the flat subdivision method. Try to see if only two Catmull/Loop subdivision steps would be enough in the disp. component itself, and not also as a geometry modifier.

I'm also not sure why displacement in this example - a normal map would do the job perfectly.

Regarding voxelisation time, there will be some time also in the non displacement test. So try to time it instead exactly from when you press the render button until the set SL is reached.

Which DT tutorial is this?

[itai bachar]

Ok, I see what you mean by 2 subdivs, Ill check it soon.
its Digital tutors - Rendering a photo realistic toy scene in maxwell
I know in this case a normal map can suffice, but Im just learning Maxwell, so its useful to know.
Thanks