MrSun is lighting up my background

[NigelStutt]

I am having a nightmare with this model! So any help greatly appreciated.

 

I am using Max 2012 with Mental Ray. I have finished the modelling. I have drawn a sphere for my skydome clouds, cut the bottom part off, flipped the normals, assigned the sky bitmap to it, set backface culling etc. I have set the sphere in object properties to not receive or cast shadows and I have set FG to 'Pass Through'. Everything looks fine.

 

But then when I choose MR Daylight system and create a sun it starts lighting up the back of the sphere with a circular patch of light that is coming from the sun by the look of it. And I have tried everything and I cant get rid of it!

 

Yet I did exactly the same thing for a render I did a few months ago and it worked exactly as it should and in that one the sun doesnt light up the back of the sphere in that render.

 

So I have been looking at all the settings etc and comparing them and I am damned if I can find anything different between the two renders but this latest one - I cant get the sphere to ingore the suns light. It was exactly the same with Vray as well - the Vray sun was also lighting the sphere which is why I changed back to Mental Ray. But MR is doing the same thing! Can anyone suggest why this might be happening to one render and not the other? Obviously the generic Max settings cant be affecting it so what am I doing wrong in the second model?

 

(PS I dont want to go down the HDRi background route because I cant see the image in the viewports unless I change to DirectX viewport rendering because of Max2012s bug, I want to use the Nitrous viewports which is why I am having to use skydomes)

Edited May 14, 2014 by NigelStutt

[NigelStutt]

The strange thing is I've just copied all of my modelling (other than daylight system and dome) into the other file with its daylight and dome retained and the skydome works exactly as it is supposed to - not being lit up by the sun at all!? Do you think this is because for my new render I started off with it set up for VRay? Could that have messed up the Mental Ray settings just for that model somehow?

 

I am still not certain that Pass Through is working correctly I will have to do some more trial renders.

 

Max 2012 seems to be very flaky actually. It crashes for no reason on occasion and things seem to disappear and reappear. Sometimes it seems I have to shut it down and restart Max to get it worked again properly after a few hours - has anyone else seen this happen at all in Max yourself?

[Francisco Penaloza]

I do not understand why there seems to be a trend of people just switching rendering engine because something does not work the way they need. You should not do this, of course it change things, materials, lights, properties everything works in a different way!! the only time that you should use other render engine is when you have features missing, like Lens effects on V Ray. or time ago MRay had a better Ao shader.

this is an oldy but goldy tutorial from Jeff P.

http://www.3dallusions.com/forums/threads/3210-How-to-Skydomes-in-3dsmax-with-mental-ray-(and-FG)

 

from Max 9 still works.

 

Now if you are in VRay, you just slap a texture in the dome light of VRay, and it will show as background simple, or just put your texture in the background slot of Max and overwrite the environment shader in VRay, and this will show your background too and not interfere with the lighting. In Mental Ray you can also put the texture in the MRay sky shader it self, as background or Haze, it will take colors of your texture for GI and also will show in your background.

or take your dome mesh and be sure that in the properties you are no casting shadows, no receiving shadows, in Mental Ray tab check pass through(invisible to FG) and do not receive illumination from Final Gather.

 

Cheers.

[Scott Schroeder]

Is your sun disk visible to camera? Are you 100% sure that you don't have any sort of opacity or refraction on your sky material? Since you are using a sky dome, there is no need for the MRSky map, so turn that off out of the environment map slot.

 

If everything works as expected when you copy everything but the light and the dome, then the problem lies in 3 places. Either the light, the dome, or the render settings of that file.