Mr Keeps Running Out Of Mem Even Tho I Have 4 Gig!

[sawasawa]

Hi all. I have quite an, shall we say, unorthodox scene. Basically, I am trying to render a 5 million polygon pumpkin!! Problem is, MR doesnt seem to like the model too much Problem most likely is a memory issue (or perhaps a polygon limit on object size?) I have tried everything. I have 4 gigs of ram under windowsXP Pro and am using the /3gig boot.ini switch so Maya/MR can allocate up to 3 gig. I have upped MR's memory setting to 2.5 gig -leaving some room for Maya and windows but this ^%$#^%#$# pumpkin still wont render! GRRRRRRR!!!

Are there any tricks in MR to get this baby to render? It seems funny to me how I can load this thing in Maya viewport and render it in shaded mode with multiple lights but cant seem to get MR to like it! Is there no hope for me? Am i going to have to wait for 64-bit computing with their better ram limits? Would buying a few more computers and networking the thing help(or am I still stuck with the measly 3 gig ram limit)? thanks for any help!

System specs:
Dell Precision workstation
Dual Xeon 2.4ghz cpus
4 gig of ram (with /3gig boot.ini enabled)
Nvidia QuadroFX1100 card agp 8x
Windows XP Pro Service Pack2
Maya 6.5

[joojaa]

And why exacrtly do you need that many polys? I mean you could just convert it to a displavcenemt and use taht. thsi makes for a much more menageable rayytrace target for mr. NOt only would this render faster it would produce better looking results too.

as far as i understand mr is big mamory aware, toughy you do bach form commandline?!

Anyway the building of the tree for such big things is super memory intense. So try set the accelartor to large bsp.

ALSO export thhe stuff into the scane as a MI file as the conversion will eat ALOT of memory in itself wich may not get fereed properly by maya so your now loading teh poly 2 times in memory.

Also try setting the task size to 1.5

note dropping of speed to 1 might mean mr has started swapping things wich can result in you in sense seing absolutely no progress since your speed just dorpped to 1/1000

[sawasawa]

Hi and thanks for the response. The displacement mapping approach doesn't work either as my subdivision approx editor will crash mental ray with any settings greater than 4 in the max subdivioin amount and the quality result doesnt look the same as Zbrush even though I have playing around with both the subdivision settings and alpha gain setting for the displacement map. The base mesh is around 20,000 triangles and a subdivions of 5 shouldnt yield more then 2 million triangles which MR doesnt seem to handle either.

I have tried large BSP tree settings and have also tried vrious memory limits from 800k up to over 2 gig

So are you saying that if I load the scene as an MI file it saves memory? SO mental ray converts the MI internally thus causing Maya and MR to both have the thing loaded?

I only see the speed drop when MR crashes. My task manager never reports any hard disk swapping and I almost always have an extra gig free when the crash occurs

thanks the assistance I will play around with your suggestions. I am sure if anything, when 64-bit Maya/Windows/MR becomes readily available it will solve these render issues. as there will no longer be a 3 gig constraint.

QUOTE(Joojaa @ 09/27/05, 02:37 AM)
And why exacrtly do you need that many polys? I mean you could just convert it to a displavcenemt and use taht. thsi makes for a much more menageable rayytrace target for mr. NOt only would this render faster it would produce better looking results too.

as far as i understand mr is big mamory aware, toughy you do bach form commandline?!

Anyway the building of the tree for such big things is super memory intense. So try set the accelartor to large bsp.

ALSO export thhe stuff into the scane as a MI file as the conversion will eat ALOT of memory in itself wich may not get fereed properly by maya so your now loading teh poly 2 times in memory.

Also try setting the task size to 1.5

note dropping of speed to 1 might mean mr has started swapping things wich can result in you in sense seing absolutely no progress since your speed just dorpped to 1/1000
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[joojaa]

What kind of dsiplacement approx do you use?!?! you should be using spatial fine on a nurbs proxy prefeerably. Also remeber you nust have a LARGE Enough texture map! Se if you have 5 milion poly and you export a 1k texture map then its probably not going tp be enough fidelity in that as it can only describe a million polys! you probably need a 4 k map

Anyway, i can easily push the diplacement up to 8 and i have way less mem than you do!

And yes its a known fact that you will not get renderers with mr with the amount of stuff zbrush can pus.

And yes you will save memory my exporting the mi. Since maya caches the exported file, and atleast at minimum yu save time for the conversion.

[sawasawa]

Hi. I use spatial approxm with view dependent set to on. I put the length setting at around 0.1. I can only render the pumpkin when the Maxium subdivision are on or below 4 . I dont get the nice "micro surfacing" detail which makes the specular hilights look incorrect not to mention the pumpkin folders don't appear as deep or as round as in Zbrush. I have also tried adjusting the alpha gain number in many different ways. I am also using a 4096x4096 16-bit RGB tif file(maxium res zbrush will export). The only way I get the zbrush quality is to export the thing as an .obj file and reimport it back into Maya .

"Anyway, i can easily push the diplacement up to 8 and i have way less mem than you do!"
How many polygons are there in your base mesh? I think this is the key in the approx numbers. My base pumpkin mesh is around 20,000 triangles

cheers,
oil-meister

QUOTE(Joojaa @ 09/27/05, 07:35 AM)
What kind of dsiplacement approx do you use?!?! you should be using spatial fine on a nurbs proxy prefeerably. Also remeber you nust have a LARGE Enough texture map! Se if you have 5 milion poly and you export a 1k texture map then its probably not going tp be enough fidelity in that as it can only describe a million polys! you probably need a 4 k map

Anyway, i can easily push the diplacement up to 8 and i have way less mem than you do!

And yes its

[joojaa]

offcotse the size of teh base is as matter but the thing is you dont want to use 0.1 (you did have view dependent chakked!) values its insanely high and gives you NO benefit. I emean if you use 0 2 min maxs ampling then 0.25 will give you as good or better with 1/2 less polys.

BUT like i said the problem is not provbably the tesselation at all but your diplacxmnet map thats WAY too undetailed for the work your doing. ALSO nbe sure to add the same thing into the bump channe (prefeerably with a normal map)l!! And use elliptic filttering.

i mean the size of the texture is ogf huge imprtance here and its overall filtering wich may be to high. Now also the way zbrush makes the maps is not optimal theres plenty of better ways to do it. but this requires a bit of work on yoru part and the shadercodes side.

But the truuth is its not hard to do a scemenwe with millions of polys. anybody can do that the trick is can you get it out. And unfortunately no amount of manoy can realy help here. Unless you use the 64 bit mr standalone wich should be able to eat much moore detai-

[sawasawa]

thanks for all the help Joojaa as u seem to be quite an MR guru!. I turned off the length paramter in my approx editor( I assume 0.0 means off) and the pumpkin seems to render without crashing(even on highe subs like 5 min 8 max)

I have noticed dis. map is crisper and more defined when I disable all filtering on it but that then seems to give me artifacts of some sort(maybe UV border related. The standard quad filter makes dis map lose all detail -very smeary looking

I would like to try this elliptical filerting option you mentioned as it seems to be a good filter from what docs says but don't know where to access it. The elliptical filtering option doesn't seem to be available in the standard texture filter pull down menus of my phong mat and online docs are vague.

mib_texture_filter_lookup seems to be the node to use for this but not sure how to link this in....keep in mind I am a MR noob I tried creating the node assiging it to a color channel of my phong but the texture I used with the node wont render -just a gray material renders in MR.

thanks for the help,
Best of luck to you