Learning MR

[kevin miller]

I have attached an in process model I am working on. The rendering seemed to be headed in the right direction but when I put the pleated blinds with translucency over the windows, I seem to be getting that "splotchy" or patchy look on the wall across from the windows. I am starting to wonder if this is a result of not enough light since I am using pretty high rendering settings (FG and GI).

 

I am using the following:

 

MR daylight (MR Sky and Sun)

MR sky portals at windows

MR photgraphic exposure control

medium FG setting with 2 bounces

medium antiliasing setting

I have tweaked the highlight/ shadow setting

Gamma is turned on

Global Illumination is on

No Ambient Occlusion

 

Are there any suggestions? I am struggling with these lighting details while learning MR as this is the second rendering with this issue.

[pfbreton]

This is a symptom associated with FG point interpolation vs density.

 

Have a look at page 18 of a document I wrote on the topic:

 

http://www.pfbreton.com/2009/11/mental-ray-in-3ds-max-at-a-glance/

 

I try to show examples of what happens with it.

 

In short, try to bake the fg points to disk then play with interpolation. Interpolation can be changed without having to re-compute fg points.

 

Hope this helps

[kevin miller]

Great article, especially for someone like myself. I am going to try some of the techniques described. Can you explain how you "bake" a FG solution to disk? I must have missed it in the article.

 

The unwelded vertices thing you mention is a concern. I import some of my geometry from sketchup and I realized it does not bring in a cube as a cube but a series of independant planes. Are you suggesting to go through and make sure the verticies are welded? I always wondered about that.

[amer abidi]

Are you suggesting to go through and make sure the verticies are welded? I always wondered about that.

 

Absolutely! Not only check for broken vertices, but also make sure all your normals are facing the right way (in this case inwards towards the room).

[pfbreton]

Can you explain how you "bake" a FG solution to disk? I must have missed it in the article.

 

In the Indirect Illumination Tab, look for the location where you can save the "Final Gather Map". Depending on the version you are using, it may be nammed differently. In 2010, its in a rollout entitled "Reuse (FG and GI Disk Caching)".