dark wall next to a lamp

Hi folks,
I was trying to build a room in blender and make it bright by setting up a fluorescent lamp right next to one of the walls. So I built a mesh that looked like the lamp and I set up a few lamp objects next to each other in a line so it looks like there would be a shining tube instead a shining spot. But somehow this doesn’t look right.

It looks like the energy on the near wall (left) is less than on the other walls. In my opinion the nearest wall to the lamp should be the brightest.

Does anyone have an idea what I did wrong?


i´ve no idea what that exactly is, but it sometimes occured in my scenes too.
It was solved by subdividing the mesh a few times. Maybe that helps you too.

nope it didn’t help

Wow that is just…weird O-o

blend file?

It’s not that weird, if you know how lamps work. First of all, you have there over 10 lamps with energy of 2.5. That is very, but very much, the area near lamps will be overburn whatever you will do. Set it lower, less than 0.5. To make it even more realistic check that Quad button, then the light intensity will decay more like in real world.

The wall material seems to be very specular. and this is not helping it.

But the lamps work as they should. When they are close to the face, that one is illuminated less that the further. The intensity of diffuse lightning depends on angle of the light ray. So the solution to this is setting the wall material right and lowering the lamps intensity.

heijulien: I think this helps when triing to illuminate the scene with radiosity, which needs many verts.

Yea missing falloff would be the first reason for the weird result. However, it is not true that the wall with the light should be brightest. Light only hits it in a very acute angle except for the small areas right around the light source. So only that area around the lamp should be brighter than everything else.

But there’s another thing that in reality contributes a lot to the lighting: reflected light. But you need a GI renderer (or give the old radiosity engine another chance) to get a realistic light distribution without additional lighting tricks.
Ambient occlusion and/or a couple of large area lights can help there, but setting that up nicely can be tricky…