Please help me, slow rendering with precalc IRR+LC

V-Ray V-Ray for 3ds Max Issues
1

Hi! :smile:

I did a big research before attempting to annoy you all, but I’m starting to
run short on time for my deadline, and for the first time I can’t tell my boss
if it’s gonna be or not ok (lots of stress/pressure actually…)

I did 2 projects before this one, with precalculated IRR+LC, everything did
go as it should, I read a lot of nice advices and comments and I also followed
the tutorial to learn how to proceed. But this time, the project won’t render
as it should.

Let me explain in short sentences (I tend to talk too much..)

I have an interior to render, with lots of textures but not many polys,
to avoid flickering during the flythrough (no object moving just the camera
inside the rooms) I follow the precalc tutorial.

the thing is that once I render with the precalc map, it renders slower
than if I do it directly with IRR and LC (or IRR and QMC)

I don’t get it.

I would like to render a 500 frames animation, the camera is panning really
slowly, so I calculated each 100frames the IRR with the previously calculated
Lightcache.

once the file is precalculated I put the IRR in the first bounce and nothing
in the second, I apply verylow preset for IRR, and choose from file.

I click render and it goes slower than without using precalculated file,
I can’t understand why, it’s really annoying me cause I’m no VRAY pro
and I can’t spot where the mistake I did is.

here is the actual test render settings: (sorry for the big size :sweat_smile: )

there is 2 vray lights in the scenes and quite a lot OMNIS (shadow map)
the lighting is exactly what I was looking for, and when I clicked render
to preview what I did, it was going from 9 to 13mn, it was the maximum
I could have because I knew the time would be less when the scene will
be rendered with precalc IRR+LC.

now, I got 28mn a frame with the flythrough method, I think I did something
wrong but I can’t find where.

I tested with really low antialiasing, and very low preset in irradiance,
nothing changed :? what am I doing wrong :sweat_smile:

I’m really thankful for your help (so is my Boss)
best regards.

2

well…is it loading the correct solution? did u check it?double check?..hapened to me before :sweat_smile:
if yes then i would advise u to load the irmap in the irmapviewer and chek ur samples…
are u cheking the second bounce to none when rendering the ouptut?

3

Hi Ene.xis :smile:

I did twice the precalc process to be sure that I followed as I should
instructions for flythrough, it actually works nicely with other scenes
where the camera fly in a hall to another room, but for this particular
one I can’t understand why it’s so much time consuming :frowning:

I never used the IRMAPVIEWER, I’ll check if everything is ok as you
advice.

The second bounce is to NONE yes, but even if I let LC in it, it seems
the time for render stay the same :frowning:

Something is not going well maybe with the IRR calculation :?

I’ll retry everything from precalc to render to see once again if everything
is done as it should.

Thanks a lot for your answer, I really appreciate, I’m starting to get
really stressed out by the deadline coming fast (this Friday)

4

V-Ray irradiance map viewer EXEcutable file

The link is broken?

5

I lowered a lot the settings in the VRay parameters and now it does about
15minutes per frame.

I’m still a little bit higher than without the precalc render, I still don’t get it :sweat_smile:

6

How large is your irradiance map?

Best regards,
Vlado

7

Hi Vlado :smile:

the IRR map is 26mb (the lightcache was 164mb), it seems things are going
better, rendering a frame is arround 15mn now (and it’s slowly going faster
from what it seems)

the scene isn’t that big, and not very heavy in polys, I admit I have big
textures, but it seems there is no memory problems. (and the texture are
about 50mb all together)

I wish I could post a picture, the GI looks really nice, I lowered a lot the
Antialiasing (-3 / 1 ) but it’s not that obvious after some composition
(the room is really dirty and pretty much trashed, dirt textures etc…)

thanks a lot for your help Vlado, I really appreciate :wink:

I’m rendering few frames to be sure there is no flickering or something
else, but from what I can actually see on the various comp I’m rendering
everything is fine. (I just wish the render time will drop to 10mn/frame
that would be great :lol: )

I render this scene through Backburner on 3 Dual CPU comp, and
another simple comp to help things getting faster.

8

hehe…we all know how s that like :?
now what i meant was if the path of the irmap was correct…if it is, well i guess that there might be some problem with ur precalc irmap…
hope u sort it out amd please do post some of those shots
:wink:

9

I did few frames now and it’s rendering around 16mn per frame.

I’m still trying to make the render goes faster, now it’ll need approximatively
2 days to render on 3 DUAL comp, not bad since the quality is good for my
humble low VRay skills :sweat_smile:

but the thing I’m still wondering is why it takes as much as if I didn’t precalc
the IRR+LC (?), well at least I have no flickering :smile:

10

:sweat_smile:

I switched off the motion blur and now it renders around 6mn/frame :shock:

since there is no big camera movement I’m thinking about leaving it that
way :sweat_smile:

or maybe playing with the camera motion blur values to get a decend MB
with a decent render speed :smile:

11

it really sounds like a bad irmap :?

12

Hi :smile:

everything is going nicely, average frame render is 5mn20sec so I’m not
affraid anymore to finish this for Friday.

another question though, I have a little problem with glossy/shiny objects,
do I have to put the light cache in secound bounce to avoid this problem?

here is a small sample - 16kb where we can see problems only on shiny mat.
it’s a quicktime file. (sorry for the small croped video and weird aspect ratio It’s 16/9)

or is it a problem with the very low antialiasing settings I have?

Adaptive subdivision:
Min. rate: -3 Max. rate: 1

Antialiasing filter:
default (area size 1.5)

Thank you so much for your help I really appreciate :smile:

13

well…
it s too small to see anything :wink:
but…
if u set the second bounce to none u have to make sure u turned off the “use lightcache for glossy rays” off, otherwise this CAN produce high rendertimes…
…it can also be related to AA since its hard to get it right in those very bright spots…
:wink:

14

Thanks a lot for your help Ene.xis, it’s hard to say I know I understand
but I really can’t post anything bigger :sweat_smile:

It’s just this shiny noise that is only over shiny materials that actually
does the probleme, this is the only area with a problem on the render,
except this it’s all good :smile:

I’m thinking about rendering a pass with just the luster and composite it
over the rendered scene, to avoid rendering all from start.

I’m not sure what is the reason of this artifact.

15

maybe try more subdivs on your metal shader - like 30 in reflect

16

Thank you Glyph, I’ll schedule a test render tonight with just the luster to
see if it resolve my little problem :wink:

17

make sure use interpolation isnt turned on on that bit of metal

18

Thank you Jacksc02, it was without interpolation already so I decided to
render in a pass the luster with max scanline, I did a metal material that
looked pretty much the same and it’s better now :smile:

I’ll finish my project today, thank you for the help :wink: