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Sully
08-22-2005, 09:16 AM
Hi I wanted to get some insight into how you guys are setting up your scenes using global illumination and final gathering..I have recently discovered that if you assign a lambert to your scene, create the lkights you want (emitting photons ect) then render your scene out with global illumination turned on and final gathering turned off to create aphoton map which you then save and reuse through out the rest of the scene creation with final gathering turned on...I have found that this speeds up rendering times amazingly.. But im my mind the logical way would be to create a photon map with all the materials assigned to the objects in your scene because different values in colour, specular ect would give the photons more energy therefore giving you a differnet more accurate photon map..the only trouble is its very slow to compute a photon map when using advanced materials such as the dgs material and genereally all of the Physical materials in mental ray..My question is, is my workflow correct creating the photon map with the lambert shader or is it more accurate to create the photn map with my final materials applied? I seem to be getting nice results with the lambert method but I want to be sure im not missing something in my workflow...:thumbsup:
cpan
08-22-2005, 09:40 AM
maybe you'r getting "No photons stored after emitted 10000.0000 photons..." warning?

when you'r using DGS_material in conjunction with GI, you need to assign a photonic material (like DGS_material_photon) to the DGS ShadingGroup as well to get it work... or better assign the DGS_material to the photon slot of your DGS ShadingGroup cuz DGS acts as a photon shader as well as a material shader.

hope the language mess isn't a problem for you to understand :)


take care
cpan
Sully
08-22-2005, 10:11 AM
Hi Yashu thanks for the quick reply, I was aware that you have to place a dgs_photon_shader I was hoping to get some feed back on how you guys go about creating your photon maps, do you use a similar workflow to me? or do you go about it in a completly different way?...Im just interested to here peoples workflow....Im reading alot of the mentalray documentaion at the moment and I know its easy to miss small details...I am not having any problems creating a scene using global illumination and final gathering I just want to see if you guys have any other cool tricks that I dont know about..:thumbsup:
LehaS
08-22-2005, 12:39 PM
when you'r using DGS_material in conjunction with GI, you need to assign a photonic material (like DGS_material_photon) to the DGS ShadingGroup as well to get it work... or better assign the DGS_material to the photon slot of your DGS ShadingGroup cuz DGS acts as a photon shader as well as a material shader.




I think you dont mind if i join your discussion...:)

...I ve got a small question though....

For Material Shader I generally use ctrl_shading separated into 3 channels, each of them plugged into mix8layer for better control......

So the network is Ctrl_shading>mix8>SG..

WHat should i pluginto Photon Shader slot in this case ?
I tryed but none of the basic photon shaders worked in that case...

Also what you guys think about getting consistency between your miMaterailShader and Photon SHader to produce proper results while using GI? Because FG uses Mi shader for its calculations...while GI uses Photon one...this produces different physical result if shaders are different...

Is there any advanced knowledge behind the process besides simple workflow of plugging the same shader into those 2 slots as you suggest ?
cpan
08-23-2005, 04:39 AM
well, for the ctrl_shading>mix8layer material, in order to "translate" it to a photon shader, i guess you have to plug a simple mi_photon_basic (don't remember the correct name :)) or a DGS_photon in the photon slot of your SG and then connect the output of every layer/ or ctrl_shading "layers" (like specular, diffuse, etc) to the coresponding attribute of the photon shader: diffuse to diffuse, specular to specular, etc.

it would be nice though to have a photon_passtrough shader so we can directly convert any material shader to a photonic one :)


take care
cpan
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