Mentral Ray work | my findings and questions

[Cesar R]

Hi guys,

 

I have been really working hard at MR and I wanted to post the following images to show you different iterations of the scene.

 

I am looking for some cirtiques and help in terms of lighting not so much the modeling although overall comments are welcome. This is a Revit model I imported to 3dsmax and replaced materials with AD materials.

 

First render,

 

 

I knew I there was something funny with the contrast and lighting so I decided to re-render playing a but more with the MR exposure control as well as redoing the GI.

 

This is the final,

 

 

^ this is a Mentralray render with GI and FG bellow is and iray version:

 

 

yes it is still kind of "raw" need to cook a little longer to clear up nicely, but one thing that I noticed is that the wall of the east of the image from where the light comes in, is much more lit up on this render that it is on the MR version,

 

On the MR version, I am using a photon radius of 10" and 60000 photons, however, if I were to make the photon radius very large to lets day 20', the wall in question becomes brigther??

 

Why is this? / what is right and what is wrong?

Another thing I noticed is that the more photons in the scene the moder defined the shadows and details are.. am I correct in thinking this?

[Justin Hunt]

you are right on both occasions.

 

Firstly the radius size, the large the radius the larger the area it averages out and very smooth. If there is a really bright, small spot with in that large area then the whole area becomes brighter. You only need a few photons to cover the whole scene, it will look brighter but there is not enough information to get good detail. To get more detail you have to increase the number of samples. You will also get more light leaks (like whats happening at the ceiling wall junction)

 

With a smaller radius, you will need more photons to cover the scene. The averaging will be over a smaller area, thus not as smooth. The lighting will seem darker, but it is more accurate as it wont be smoothing out samples from further away. Being a smaller area you only need fewer samples.

 

So rather use a smaller radius and use FG interpolation to smooth the lighting solution out and exposure control to brighten the scene.

 

Post your render setting, there might be a few more tweaks to be made

jhv

[Cesar R]

Light leaks on which image? the first one?