View Full Version : optimizing rendertime for animation

02 February 2005, 11:15 AM
hi folks,

befor I head into the final phase of my short movie, I start to think abbout how to render it. The movie will be something like 5 minutes, so if I use 25fps that gives 7500frames.

7500 images to render. thats a lot.
So I can:

a.) optimize my rendertime so much that my single home computer (apple G5 2x2gig) can do it all on its own. I will ask some question bout this later.

b.) buy some renderslaves; cheap pcs that help me do the job. ... here a good question would be what to by and wich system to run on them (XP or linux) also here I would have upgrade from maya 6 to 6.5 to have to more mr renderlicenses. right?

c.) look for some comercial renderfarms and the prices.

ad a.)

at the moment I am at 3 minutes by frame. 720x576
that would be 375 hours (15 days) rendertime for the whole 7500 frames :hmm:
I use mental ray, I baked some shadows to the texture and use one spotlight with raytraced shadows (14 shadow rays). some other lights as fillers without shadow.
the antialiasing is set to -1/+1 what is still to low. but when I give it 0/2 this the rendertime goes up a lot.

It would really help a lot to help me here and share your experience.
I also can offer to mail the scene to people who want to take a look at it, trying to optimize it.

thnx in advance

here is the link to the movie and two images ( though they are rendered with a antialiasing of 0/2). the movie lost some quality in compression, but the main bugs are due to the too small antialiasing. _ sorenson3 _ 2.0MB (

02 February 2005, 11:45 AM
Hi mimo8!

In order to observe the rendering, did you allready turn the MR verbosty to progress Message.
setAttr mentalrayGlobals.exportVerbosity 5;

At first look the biggest cost can come from the fur.
You may allways start the main rendering and add the fur in post when you'll have the result and performance you're expecting...

02 February 2005, 12:05 PM
Looking good there.

I would try rendering your character in a seperate pass, especially when the camera is not moving. This way a single frame for the backgroung is enough.
And using a depth map shadow might help too, give it a try.

On a side note I'd use a dirtmap shader (and bake it into the file texture) on the tubes, they do look strange where they meet the ground, some kind of contact shadow is needed there.

02 February 2005, 02:40 PM
thnx for support,

your comment bout the fur really made me happy, cause THERE IS NO FUR :bounce: :bounce: :bounce:
its just texture and a velvet shader.

yes I swithced over to depth map shadow and this is a huge speedboost.
I switched raytracing off completely.
so its just one spot that is dupplicated to imitate soft shadows (the good old trick)

for the tube:
I dindīt care abbout their texture at all till now.
dirtmap and glow will be two passes that I render seperately - both of them render quite quick.

all the textures are still changing a lot.

I will post some more images in a moment

02 February 2005, 02:44 PM
another question:
using "disked based Dmaps" is like baking them,or? I never used that.
so this cannot be used for moving objects?

02 February 2005, 02:56 PM
rendertime is much better allready.
one frame takes 1:20min now, BUT antialiasing is crancked up to 0/2 (what should be fine I hope)

perhaps I should play with the texture resolution.
at the moment I use 2000x2000 for the box (1000x1000 doesnt look crisp enough)
but I am not sure lower textures will bring such a speedincrease ?
also I could check the polycount. but I modelled carefully ...
the whole scene has 30.000 faces at the moment, that doesnt sound too heavy to me.

another question:
when I start my batchrendering looking art the progress message I see a lot of errors.
some tell me that the turtle render (that I once installed and dont use now) is not found, others complain abbout connections of some nodes of the lights, others worry bout the rig and the constraints of the character.

nothing that is really bugging me.
I think Mray goes through this things just once when it reads the file in. so if you batch render an animation it doesnt do so for every frame.

my question is, would you go through the scene and also my maya setting (turtle) to get rid of all this error message, or wouldtn you care (like I do now)

02 February 2005, 04:06 PM
Congrats for the fur! ;)

About texture resolution you may also convert some of them to a format.
imf_copy -pv /path/sourceimage/file.iff /path/sourceimage/
You'll get a memory friendly fileformat for mentalray.
Anyway I suppose It won't change renderingtime that much.

About error message I would'nt care.
1:20min Is a allready nice performance if your AA settings are 0:2

02 February 2005, 05:53 PM
thnx rolly ;)

with this thread I also was asking for some special mr settings that I didnt see so far.
I just know that you can turn down the BSP depth from 40 to 20 in the mr render globals under rendering ... I saw once that Jozvez did so, but I am not perfectly sure what this does.

I will have to try out this .map file format thing ... new to me.

here is my output so far - with dirtmaps - cinepack - 650k (
its very fast .... just scrub trough like a panorama

Mr Majestic
02 February 2005, 06:16 PM
do u have a fisheye lens thing goin on there or what, Im just tryin to figure out y the light seems to be squeezing in and out.

02 February 2005, 09:43 PM
no its not a fisheye lense, its a deformer on that lamp.
the lamp is a crucial part of the story and its is allways a bit bouncing arround up there on the ceiling .... you watched it closely

but indeed there is a strange thing going on that I dont get by myself.
on frame 3 the light is getting much dimmer, either it is that bouncy lamp getting in the way of the lightspot, or it is the glow on the lamps shader that makes this change of illumination.

02 February 2005, 10:05 PM
Hi mimo.
I just suggest to not move you're camera a lot-unless you designed your short like that- and render things seperatly then you could add some zoom and pan in post.
Good luck.
I really like your work. looks very nice so far, keep it up my old friend.

02 February 2005, 10:19 PM
thnx lazzhar, thnx a lot for the for your compliment,
things like that keep me going :)

this brings in another aspect into making a 3D movie and how to handle the camera. the first scenes animation is finished so far, but I will try to keep as many shots steady for the following scenes ... thnx

another technical question:
what is the difference between
MSG 0.0 info : wallclock 0:12:02.83 total
MSG 0.0 info : CPU user 0:16:28.67 total

03 March 2005, 12:54 AM
I've only been using Maya for a couple of months, (yeah - I'm a noob :-) ), but I'm pretty sure that wallclock is the total time from start to finish, and "CPU user" is the amount of time the processor was being used by the renderer. So, let's say your batch render takes one hour of real time. If you were working on your computer while it was rendering, the rendering process probably only got to use 50% of the machine's clock cycles. So the CPU user time would be 30min.

Like I said, I'm not positive about that, but it makes sense to me...

Great work, btw! I love the shots you've posted. I've been trying out some of the things people are suggesting here in my own scenes - and it's helping a lot.

03 March 2005, 03:23 PM
3 Minutes... that's not bad for MR.
Anyway, if you want speed, MR is not at all your best choice. The results of Renderman would have been just as good and at probably... some 10-20 seconds per frame...

03 March 2005, 08:00 PM
last year a completed a piece for a friend that ran 20 min. I had a lot of the issues you're bringing up about frame render time + number of frames on a single home machine. Because of the time commitment I had to the render I rendered everything in multiple passes: Foreground elements (and a few passes for them), background elements and sky. While I think my render times were a bit longer per frame to do it this way my ability to save a ton of re-rendering at the end really saved it. I could bang out a few foreground frames or render to a point where the bg is still or obscured then pick that up later. I also had a few glows and whatnot that is far easier to control in 2d than right out of the render.

Not sure if that's any help for you, but I know that generally I make mistakes or change my mind about things, rendering in passes lets me make those choices w/out major consequences.

Good luck w/ your piece, it has a nice look to it!


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