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zuao
08-17-2004, 12:54 PM
Ahoi,

it's very refreshing to watch all the Maya People doing this exciting stuff with and for mental ray. I'm saying this because I'm using Softimage Products alongside MR for 5 years now (nearly 4 for Maya). Just the time when you're beginning to think you're omniscient about MR rendering. Of course, that's nonsense.

When I got the chance to do beta-testing for Mayatomr in May 2001 I was really surprised by its capabilities at that time, because it already could translate a lot of my Shading Networks. Now everybody could play with the new toy, but I think there is something that is covered rarely and treated superficially by many MR users. I always notice that when I'm into some project and the people start their renderings and wait and wait and wait or complain about memory overflows.

MR provides possibilities to deal with these issues. You will find it in the "MR Render Globals" under "Memory and Performance" and it's about the "Acc Methods" called BSP (Tree) and Grid. These are powerful settings which have great impact on rendering time and memory usage EVERYTIME you're using MR.

I don't want to explain the whole thing here, because other people already did in excellent papers. So, this is just a reminder from me.

Take your time an read these, you will gain from it. Both in english.

"Techniques for Optimizing Rendering in SOFTIMAGE|XSI" (http://www.softimage.com/Products/ProRen/media/XSI_rendering_lajoie.pdf)
Author: Dave Lajoie, Senior Consultant & Rendering Specialist, Softimage Co.
October 2003

"Mental Ray - tips and tricks" (http://www2.festival-gmbh.de/sixcms/media.php/108/TipsUndTricksZuMentalRay_ThomasDriemeyer.zip)
Author: Thomas Driemeyer, Director Software Enginnering, mental images GmbH & Co. KG
May 2004, fmx/04, Stuttgart (Germany)


Regards,
nando.

Jozvex
08-18-2004, 04:26 AM
Yes! You're absolutely right (of course), BSP settings are quite vital to getting fast rendertimes (or being able to render at all in some cases with huge scenes). Thanks for posting those PDF links, I haven't read the second one I don't think.

:thumbsup:

___________
EDIT:
___________

That slideshow was good. I really wish there was a graphical imf_copy program though, I hate doing things via command line. Something I've been wondering lately though is about Geometry Shaders, are they included in the BSP Tree?? Because when you use the BSP diagnostic modes they do their diagnosing before the geometry shaders are called, which makes me wonder about whether the shaders are even included in the tree at all.....I suppose I need to do some more researching. :hmm:

I also wonder if there's a way to visually diagnose FG Falloff? Not that we can even display diagnostics for FG at all yet in Maya (to my knowledge at least, apart from the FG Map Visualisation feature which is great but not quite the same hehe).

Haha, I guess I could just buy the damn MR manuals and stop all this wondering, but I'm too scared that I'll buy them and then they'll release the new versions.

:scream:

francescaluce
08-18-2004, 04:28 PM
out.of.topic

I really wish there was a graphical imf_copy program though, I hate doing things via command line.donno what are you doing with the imf_copy.. but here a little plug I made to use it directly from photoshop.. currently only for the .map format conversion.


http://www.cgtalk.com/showthread.php?p=1333894#post1333894 (http://www.cgtalk.com/showthread.php?p=1333894#post1333894)




ciao
francesca

MunCHeR
08-18-2004, 05:18 PM
Thanks for the great links nando, I have found a lot of information on mental ray rendering that either don't explain the why's and how's either thoroughly enough or too well in which case you just get too much information that is incomprehensible, then again its probably just my brain, anyhow, its been a good read, thank you:thumbsup:

MunCH

zuao
08-18-2004, 06:12 PM
By reading another thread today (sorry can't remember which) I realized, that there is one resource more, that I want to drop here for completion. Maybe the best one to really get into MR. I'm talking about the books "Rendering with MR" and "Programming MR" written by Thomas Driemeyer. Some of you certainly already know. If not take a look at the link.

mental ray Series of Handbooks (http://www.mentalimages.com/2_1_3_literature/index.html)

Ciao,
nando.

zuao
08-19-2004, 12:37 AM
I really wish there was a graphical imf_copy program though, I hate doing things via command line. Search for "imf_copy" on Highend in Maya's melscript/utilities section. You will find "Riess imf_copy GUI"

-EDIT-
riessImf_copyGUI_v1.1 on Highend (http://www.highend3d.com/maya/mel/?section=utilities&minl=150&maxl=50&sort=file_name#3003)
-EDIT-

---
about Geometry Shaders, are they included in the BSP Tree?? Haven't done that much with Geometry Shaders lately, but I know the GS are called at preprocessing stage, which means before rendering (like displacement shaders). In this case the created objects should be included in the BSP Tree calculation, right? It would makes me wonder, if not.

---
I also wonder if there's a way to visually diagnose FG Falloff? Hm, I remember that I was wondering about the same issue once. Perhaps the dirtmap could help? I tried this: the dirtmap with ray spread=90, near clip=your FG Falloff value, far clip & falloff gain=0. This one connected to a Contrast Node with ContrastRGB=10 and BiasRGB=0.999. This Node connected to a surfaceShader - certainly to visualize what I've connected :) ... You think, this could do the job? Err :rolleyes: ... it would be more sexy, if this would be a checkbox in the Render Globals

---

ciao folks,
goin to party now,
nando.

Jozvex
08-19-2004, 02:17 AM
out.of.topic

donno what are you doing with the imf_copy.. but here a little plug I made to use it directly from photoshop.. currently only for the .map format conversion.

That's great! Thankyou! All I needed was .map conversion. :thumbsup:

In this case the created objects should be included in the BSP Tree calculation, right? It would makes me wonder, if not.

Yeah, it's weird because Maya Fur doesn't show up in the BSP diagnostics even though it uses Geo Shaders.

You think, this could do the job?

That's a great idea! I'll try it out!

:thumbsup:

Jozvex
08-19-2004, 09:36 AM
Francesca, your PhotoshopCS script doesn't let you choose a Maya path to specify the IMF_DIR. Luckily I have XSI Experience installed so I just used that path instead.

:)

mrgoodbyte
08-19-2004, 03:45 PM
Yeah, it's weird because Maya Fur doesn't show up in the BSP diagnostics even though it uses Geo Shaders.


That's because Fur is in fact a post process by the Fur renderer instead of Maya/MR. BSP trees only applies to these renderers. Same thing goes for Paint Effects. These post processes work by rendering and layering elements from the back to the front

Jozvex
08-20-2004, 01:22 AM
No no, for Mental Ray the Fur isn't a post process, only for Maya Software. That's why in Mental Ray your Fur can cast/recieve GI and caustics etc. And be rendered through refraction, whereas in Maya Software it can't.

Nolan
08-20-2004, 04:46 AM
Jozvex this awt to help you make your mind up about buying the Rendering with mental ray manual.

http://www.springer.at/main/book.jsp?bookID=3-211-22875-6&categoryID=3
Forthcoming 2004/10

Jozvex
08-20-2004, 06:48 AM
GREAT!! The new third edition of 'Rendering with Mental Ray'!!

Thankyou for posting that!! I'm going to buy it right now hehe. It even comes with "Programming Mental Ray" second edition free on the CD!

:thumbsup: :thumbsup: :thumbsup:

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