Blurred Reflections???


I’m using Mental Ray and am using a highly blurred reflection for quite a few of my textures (made using DGS materials) but they are extrememly grainy unless I turn the sampling up to 0/3…which as you can imagine creates HOOORRRRIBLY long rendertimes. I was just wondering if there is a better alternative to the blurred reflections, and also if there is a way just to set samples for the reflection rather than the whole scene. Everything else renders fine at 0/1 so it’s overkill for me to have the entire scene at 0/3. Thanks alot.


if I remember right, the oversample_lens shader gets used in this situations… try pluging one in the rendering camera’s lens shader slot and then modify it’s parameters to tweak… someone who used this shader could explain you better btw



try to use the reflection utility wich have a sampler for the blur in conjunction with a good contrast threshold and a low AA (0/1, 0/2)
or use the ctrl_shading by francesca luce :wink:




Or use a plain phong maybe?


Blur reflection shader with independent sampling (like reflection maya shader), coming from xsi node. To use it, you must have the sibase.dll

Attached .mi file for connection to maya


I post here the new ctrl_shading.
there’s update only on the reflection
part. it distingush now really the
fg precomputing phase from the
render phase. this means that one
can supply fewer samples or even
a completely mirror reflection (as I do)
to the fg.phase to get computed the
blur only on the render phase. this
can speed up terribly heavy glossy
reflections in fg production renders;
the results are almost indistinguishable.



one more time thanx francesca! :thumbsup:
this shader rocks!
i will try to use it in the classroom test :wink:


absolutely unbelievable francesca!! :thumbsup:

1 direct + ibl
fg multibounces
rays 400
rad 2 / 50

aa -1 / 2
mitchell 4 4
c. threshold 0,05 0,05 0,05 1

dgs (no sampling)
rendertime: 3m 37s
fg calc: 2m 30s

dgs + reflection utility (sampling = 8)
rendertime: 5m 36s
fg calc: 4m 39s

blinn + blur reflection (sampling = 8)
rendertime: 6m 55s
fg calc: 5m 46s

ctrl_shading optimize OFF (sampling 8)
rendertime: 5m 28s
fg calc: 4m 33s

ctrl_shading Optimize ON (sampling 8)
rendertime: 2m 31s
fg calc: 1m 35s


Thanks for the tests dagon. I would add a phong test though, since blinn does additional calculation regarding the reflections, tampering the renderingtime comparison.


:thumbsup: i can try with the phong too
but the ctrl_shading really shine with the glossy reflections!!! :scream: :scream: :scream:


Hold on! I never said it would be slower, I just wanted to have the total conviction. :smiley:



phong + blur reflections (samples = 8)
rendertime: 6m 02s
fg calc: 5m 19s


Perfect! :smiley:


dagon, thanks for the tests.
really thanks. :slight_smile:



:: francesca or dagon :: how do u connect ctrl_shading to the material slot? i allways get crashes when i do the default connection :(. Please post a shading network image if u can.
Oohh, almost forgot to ask… does this shader acts also as a photon shader?




thanks to u francesca! this is a great shader! now i’m making some test with the classroom scene (very hard for the glossy shaders)… :wink:


use a passthrough… or connect the compound output of the ctrl_shading to the mix8layer :wink:


Is there any chance to get this shader working on 6.0.1?


no sorry it requires mentalray3.4.



wow, that stuff looks great, I can’t believe how quickly that rendered with such good sampling! Can’t wait to try this out.