Small Importons and Irradiance Particles Tutorial.
They are not just useless toys, they does WORKS GREAT.
Since that the “Importons and Irradiance Particles thread” seems to be idle, I decided to share my findings by opening a brand new thread.
First Thanks to Max (Ctrl Studio) for recompiling the Ctrl_Ghost Settings.
A big thanks as usual to the “Mitico” Dagon, to find out the correct way to use them effectively.
Before to proceed with the technical details, I really hope we will get some feedback this time, from the guys at “Autodesk” and “Mental Ray” former “Mental Images” now owned by “Invidia”.
I would like also to stress out, that I find pretty insane that Maya & Mental Ray artists
like myself, must invest several years and put a lot of efforts,
debugging the Maya & MR software, testing and trying to get basic
and new unimplemented features to work as expected…!
Quote Dagon from the “Importons and Irradiance Particles thread”:
“I think we should ask for a contact (a forum with bug reporst, wishlist, etc?) with the mray developers, or at least with the OEM integrators (anyone has ever known who’s for maya?)”
“I dont know, is not a personal problem, i think we should start to make a petition (or something like this) to ask better support on the autodesk side.”
Please excuse my little off topic complain.
Now back to the main topic…!
This new features requires a good knowledge of MR, so before to mess around with this new settings, I suggest to all the young MR artist out there, to go through the other
MR threads such as “VRay-like interior renders with mental ray???” and the new “Six Tuts On Light And Shade // mental ray for Maya” by FLOZE, first.
After reading through the “Importons and Irradiance Particles” thread, I was thinking that if we could get them to work, it will be a small revolution in Mental Ray rendering, since this settings will allow us to use MR in a Vray fashion.
So I start to test them with the tecniques explained in the thread, with simple Cornell Box maya scenes.
Quote Max from the “Importons and Irradiance Particles” thread:
"A couple of things to use Importons and Irradiance Particles in Maya2008SP1.
You should avoid any maya shader:
‘Suppress all Maya Shaders’ should be checked. ‘Export with Shading Engine’ instead shouldn’t be checked, in the shading engine node (tests were made with mia_material).
The same goes for lights. ‘Suppress all Maya Shaders’ need to be checked, and a custom light shader should be supplied (mr sky portals work good).
Finally, in the Rendering Settings, goto Translation->Customization and de-check the ‘Export State Shader’."
After a few crashes and a few disappointing results, I decide to test them with my standard MR settings and with big surprise everything start to work out AMAZINGLY FINE…!
So based on my tests, to make this features work in Maya2008SP1:
- You can use any maya shader.
1.‘Suppress all Maya Shaders’ shouldn’t be checked.
2.'Export with Shading Engine’instead should be checked.
- The same goes for lights. ‘Suppress all Maya Shaders’ shouldn’t be checked, and a custom light shader should be supplied (mr sky portals work good).
4.Finally, in the Rendering Settings, go to Translation->Customization and check the ‘Export State Shader’.
With this settings everything will work as expected, and you just will get a warn message from Mental Ray during the Importon Ip calculation which goes like this:
“PHEN 0.3 warn : maya_state(): Called on an unexpected ray.”
Which I guess is safe to ignore.
I’ve tested this features by rendering both from the main render window, and from the batch render.
Quote Max:
“Another feature that comes with mr3.6+ is an advanced framebuffer memory management. Indeed, the cached mode. When in cache mode you can render any image size (even on 32bit). In fact, if enabled, only a small fraction of the resulting image (or user framebuffers) is present in memory: newly rendered tiles and tiles recently accessed.
This mode should be used only for batch rendering (it will crash maya if used for the render view… also it does not make too much sense rendering big size images in a viewer). I just rendered a 20k image, in floating point, on a 32bit system. Slower than the others methods, it should be used only if mr is not able to create a framebuffer of a huge size (generally more than 4k images on 32bit).”
By creating first a user framebuffer from the Render Settings window, with standard RGBA (Byte) 4X8 Bit, feeding the advanced framebuffer memory management, in the miscellaneous section of the Ctrl_Ghost Settings window, with the value (1), I’ve managed to render EXR
floating point, big size images on my Intel Quad 9300 32bit system.
Without any crash, and I also get rid of a tedious error message
which was saying that MR couldn’t create the main framebuffer(0).
Max please feel free to correct me if I’m wrong, because I’m not a MR programmer…!
Please note that all the rendering tests, was done with 2 very heavy maya scenes:
The Jeff Patton exterior which is almost 197 MB. huge size caused by the XFROG trees.
The Jeremy Birn Christmas Interior is almost 193 MB., because this scene is filled by evermotion high detailed 3D objects.
Here we go with the result of my small reseach:
- This image was rendered without Ctrl_Ghost Settings, with the old FG/GI algorithm.
Maya 2008sp1 with MR Physical Sky/Sun & Mia X Materials only, and one Portal Light behind the window.
The Light emitting from the wall lamps, the Christmas Tree lights and the Fireplace, was achieved through the additional parameter of the Mia X Material, to which I connected Mib Light Surface shaders.
Please note the light blotches caused by the light emitting objects.
Based on my tests, too achieve a good light distribution, you should just increase the FG filter, or increase the FG Density and Interpolation Points, which will also increase render time insanely.
Render time with 50 Interpolation Points: about 5 hrs.
- This image was rendered with Ctrl_Ghost Settings, FG/GI & Importons enabled, Density 1, Emitted 100000, Merge 0.1, Size 256, depht 4 and IP disabled.
Please note the much better light distribution compared to the old FG/GI algorithm.
Render time: about 5 hrs.
- This image was rendered with Ctrl_Ghost Settings, IP & Importons enabled, and here comes the very smart solution pointed out by Dagon, based on the old FG map freezing technique.
First you have to launch a render through the batch render, which I prefer, or through the main render window, with the Importons settings as follows:
Density 1, Emitted 100000, Merge 0.1, Size 64, depht 4.
IP settings: rays 64, passes 4, interpolation never, interpolation points 64,scale 1,enviroment enabled, enviroment rays 64, enviroment scale 1, rebuild enabled and provide an absolute path on your hard disk, that points to a file with an .ip extension.
Name the file as you like.
After the Importon & IP calculation phase, MR will save the .ip file on your hard disk, and will start the main rendering phase.
Now you have to interrupt the rendering, and go back to the Ctrl_Ghost Settings window and replace the Importons settings as follow:
Density 1, Emitted 100000, Merge 0.1, Size 256, depht 4.
IP settings: rays 256, passes 4, interpolation always, interpolation points 256,scale 1,enviroment enabled, enviroment rays 256, enviroment scale 1, rebuild disabled, and provide the absolute path on your hard disk, that points to the .ip extension file previously created.
Now you start a new render through the batch render, which I prefer, or through the main render window, wait a few hours (5/6 hrs. in this case) and VOILA’.
- This image was rendered with the same technique as image n.3, just with the Importons Density 0.2, Emitted 0, Merge 0.1, Size 256, depht 4.
I feel that this image, compared to image n.3, is a little bit darker. It seems that Ambient Occlusion is much more present.
Render time: about 6 hrs.
- This image was rendered with the same technique as image n.3 and 4, I’ve just increased to 4 the Color Gain of the Fire image, dropped into the additional parameter of the Fireplace Mia X Material.
Please note the bright red spots on the walls and ceiling of the room.
Render time: about 6 hrs.
I guess you could get rid of this red spots, by increasing the Density to 1 in the Importons settings.
Or just playing around with the Indirect Illumination Options of the Mia X Material, or the Mia_Light_Surface.
Considering the huge size of this maya scene (193 MB.), I could not manage to increase the
Density to more than 0.2 in the Importons settings, because Maya was just crashing down…!
Since I’m a little bit tired at the moment, I will appreciate any help or suggestion on how to get rid of the red spots, maybe Max and Dagon could help us out one more time…?
- This image was rendered with the same technique as image n.1, with the old FG/GI algorithm.
Maya 2008sp1 with MR Physical Sky/Sun & Mia X Materials only.
Please note that the wooden planks material seems to be more bright than the next images, just because for this one, I used very high raytracing values.
Render time: about 5 hrs.
- This image was rendered with the same technique as image n.2
Render time: about 5 hrs.
- This image was rendered with the same technique as image n.3, with only 50000 Emitted Importons.
Render time: about 5 hrs.
- This image was rendered with the same technique as image n.4
Render time: about 6 hrs.
- Just a simple test with Fur.
Enjoy with this new features…!
Ciao…!
Alex Sandri
http://www.samui3d.com
PS. I hope I was enough clear, and please excuse my english, because like Max and Dagon I’m Italian, too…!
opsss 
bye bye