Lines to corner glitch

[iwojap]

I'm using photon mapping in Blender and getting a weird visual artifact that leaves white (and black) lines leading to the corner of the room in this model. This should be a solid surface. No idea why this is happening. Renders solid in Cycles.
https://drive.google.com/file/d/0B28ESHgLWd0oVW5Xa2llbjZ5cWs/view?usp=sharing

[kenanaybati]

The walls have some thickness?

[Samo]

I don't know if you are using cm as blender units instead of meters, but if yes then maybe is a mesh self shadowing problem. In the bottom of the render panel, there is an "Advanced Settings" section, I would play with the "Min. Ray Dist." setting.

[iwojap]

Yes, there's thickness.

The "Min Ray Dist" setting fixed the problem. Thanks for that.