Here’s a quick and flexible way to emulate the look of fog in the background of an image. I recently used this technique in the visualization of the Agami House in Yaffo. It’s true it might not look real enough but for most cases this really looks good enough and you have the added bonus of fast render and flexible edit inside Photoshop if the client ask for tweaks.

This is how the SketchUP model looked just before exported to 3dsmax to be worked with VRay for the final rendering.