PDA

View Full Version : Some useful rendering tips in mentalray for Maya.


samsan8
06-27-2011, 06:59 AM
http://fermicg.blogspot.com/2011/06/mentalray-in-maya-killer-tipsrender.html

Bitter
06-27-2011, 09:19 AM
Nice guide, but some of these could be updated some.

-I would avoid using radius controls for FG, it's harder to tune with radius.
-Increasing rays instead of interpolation is less of a render hit. But they also have different consequences. More rays for complex lighting, more density for complex geometry.
-The dome or cube idea is designed to stop photons from traveling into nothing and not being stored, that's not a FG performance consideration. Maybe a typo.
-Use tiled EXRs instead of .map
-rendering shadows separately means multiplication in post and should be avoided if possible.
-reducing the size of the HDR map is fine unless it's used for a reflection map as well in which case you might lose details
-combine objects into medium sized objects, sort of a middle ground is best.

Something to add at the top of the list that would be great is:

-Turn OFF Scanline.

This will reduce memory usage and speed rendering at the same time. :)

The rest of these are pretty sound, especially the ones involving shadow rays. What eats the most time for renders I get to fix are the mass amounts of shadow rays being shot everywhere. It can be a huge render hit.

Zaru
06-27-2011, 10:41 AM
Avoid .tga textures.Convert them to jpeg(separate rgb and alpha).
I'd like to inquire about this particular point. What is wrong with Targas?

samsan8
06-27-2011, 11:19 AM
@ bitter,
Thanks for sharing your valuable opinions......
I have never used scanline render turned off, Definitely I will check it.
shall I copy your points in to my blog?



@ Zaru.

There is nothing wrong with targa files.My point is that they are uncompressed formats,so use high amount of memory.If you have a lot of RAM compared with the scene it will not be a problem.TGA will give the better result too.....

Zaru
06-27-2011, 12:24 PM
@Samsan8, I don't think that's entirely true. Unless the file format is something sophisticated, like MR's map is, image files would take up virtually the same amount of memory when loaded into RAM, no matter what their compression is. They have to be decompressed into raw bitmap anyway. Just to assure myself I'm not lying here, I've run a small test with a generated 4k cloud map containing some coloured spots and saved it into different file formats. The results, when loaded into fcheck, were as follows:

FILE FORMAT==============RAM USAGE====HD USAGE
JPEG (min compression)...24,832MB.....13MB
JPEG (max compression)...24,884MB.....593kB
TARGA RLE................24,920MB.....39MB
TARGA....................24,778MB.....48MB
BITMAP...................24,776MB.....48MB
TIFF (uncompressed)......24,796MB.....48MB
TIFF LZW.................24,912MB.....17MB

Image used (downsized to 512):
http://img861.imageshack.us/img861/4566/testimg.th.jpg (http://img861.imageshack.us/i/testimg.jpg/)
While I admit that I've never had the guts to test texture RAM usage directly under Maya, I can't see why it would differ.

Great list of tips, BTW. Thanks for sharing. :buttrock:

samsan8
06-27-2011, 12:38 PM
Ok I agree........Thank you for sharing......
I will delete that point about tga from my blog.

Any suggestions?


:thumbsup:

ytsejam1976
06-27-2011, 01:09 PM
The fg radius and multiframe togheter 10-100 are usefull for all my scene in cm. All architectural scenes.

Eshta
06-27-2011, 02:27 PM
-Use tiled EXRs instead of .map
.
I thought EXR are automaticlly tiled ?

crispy4004
06-27-2011, 03:18 PM
@Samsan8, I don't think that's entirely true. Unless the file format is something sophisticated, like MR's map is, image files would take up virtually the same amount of memory when loaded into RAM, no matter what their compression is. They have to be decompressed into raw bitmap anyway. Just to assure myself I'm not lying here, I've run a small test with a generated 4k cloud map containing some coloured spots and saved it into different file formats. The results, when loaded into fcheck, were as follows:

FILE FORMAT==============RAM USAGE====HD USAGE
JPEG (min compression)...24,832MB.....13MB
JPEG (max compression)...24,884MB.....593kB
TARGA RLE................24,920MB.....39MB
TARGA....................24,778MB.....48MB
BITMAP...................24,776MB.....48MB
TIFF (uncompressed)......24,796MB.....48MB
TIFF LZW.................24,912MB.....17MB

Image used (downsized to 512):
http://img861.imageshack.us/img861/4566/testimg.th.jpg (http://img861.imageshack.us/i/testimg.jpg/)
While I admit that I've never had the guts to test texture RAM usage directly under Maya, I can't see why it would differ.

Great list of tips, BTW. Thanks for sharing. :buttrock:

Very interesting. For a simple textures, PNG is usually my go to format when space is an issue for me (otherwise it's TGA). Great file sizes, always lossless compression, and I've never had any issues with them and MR.

Is there something I'm missing because most of the time it's either Tiff or TGA for people, and I can't stand Tiffs because unless you do otherwise, it will save all the layer data from photoshop which is hardly efficient for rendering.

Bitter
06-27-2011, 04:22 PM
shall I copy your points in to my blog?

Sure, no problem.

I thought EXR are automaticlly tiled ?

EXRs are not necessarily tiled by default. imf_copy in Maya 2012 should create a tiled EXR by default even if you only specify the -p flag and save as EXR.

You can also use tiled .tiff files as well.

Ekenryd
06-27-2011, 05:03 PM
Is there something I'm missing because most of the time it's either Tiff or TGA for people, and I can't stand Tiffs because unless you do otherwise, it will save all the layer data from photoshop which is hardly efficient for rendering.

I think I read sometime long ago that one should not use compressed fileformats because then the renderer have to uncompress them before rendering, which adds to rendertime. Donīt know how true that is, although it sounds logical. But I guess with todays cpu-power the time it takes to uncompress shouldnīt be an issue unless you have a zillion textures.

doctorcillo
06-27-2011, 06:00 PM
Thanks for sharing these tips guys!

Taunise
06-28-2011, 01:46 AM
anyone have thoughts on using uncompressed pngs as your texture formats? I found they work rather nicely and they're small...

CGTalk Moderation
06-28-2011, 01:46 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.