Using default white material looks dirty when i render??

[Franchais]

Hi ive been having some problems while rendering with a white material. It looks dirty on some parts. but when i add an actual material this never happens? Any help would be appreaciated! thanks!

[aristocratic3d]

You need to provide more info. what did you mean by white material?

[Franchais]

Oh sorry, I meant using te diffuse colour white. I want the final material for the building to be painted white concrete so I thought just using the diffuse colour white would be good enough, but I always get these murky spot around? You can check out the pictures I posted on my first post if you have not.

[BrianKitts]

It's not dirt, but rather a lack of sampling in your GI solution. What you're seeing is he GI solution fighting between the stark difference in colors in your scene. From one point a sample ray may sample white, but in the opposite direction it might get a bounce from a dark area, when it blends it without enough samples to really evaluate the scene you get blotches everywhere. It's actually still there when you're material is applied, it's just not as a noticeable.

 

You need to up your the number of hemisperical samples when your have a scene like this specifically with really shadowed areas where direct light doesn't reach.

[aristocratic3d]

If the issue is not what Brian said (I believe he is right). then use a "vray color" map in your diffuse slot. test it again.