I can’t seem to get Radiosity working. I tried following a tutorial exactly as it said and yet, when I hit Go (after doing collect meshes, etc.), I still come out with pure black. Could I have messed something up?
You need to make sure the Rad button is pressed in the render buttons. (F10)
You will also need a light source, usually a material with an emit value set above 0.000 in material buttons.
It’s a bit hard to tell without a screen shot or image.
Sonix.
I did all that. Thanks for replying by the way. 
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I think you have to increase the max iterations from zero to lets say 50. Higher iterations = longer calcullation and better looking.
Also make sure your normals are pointing in the right direction, because if they aren’t the scene willl look black. Found this out myself by trial and error.
with max iterations set to zero the radiosity calculation will continue until there is a small amount of energy remaining [determined by the convergence value, higher value worse results in faster time]
yes, as it seems you’re doing a box make sure your normals are pointing inside [turn off doublesided for your mesh and you should see the back side of faces turn black, you want that to be the side of the faces that will never see light] with control+shift+n
furthermore, do you have any materials with an emit value applied to faces of objects which you selected before pressing the GO button?
J_Octane: Thanks, but I’ve set it 0 so I can stop it when it looks good. At least, that’s what I thought it did. %|
z3r0 d: I’m not sure what you mean. I’ve place a simple plane at the top of the big box (right below the top) and set it’s emit to about .1 and then a smaller box inside the big box is set to about .004 The big box doesn’t have anything on it. shrug I’m a little confused, I guess.
Thanks for the responses, guys!
make sure you subdivide your meshes, also, that normals are facing in the right direction.
By the way: Even if I set Max Iters to about 1000 it still stops almost right after it starts, and the box is till black.
I did that. The normals are facing the right directions and they are all subdivided (using the mesh subdivide) about 5 or 6 times each.
Okay, now the black has dissappeared, but when I press go it stops here:
And it looks really crappy. Notice I set the Max Iterations way up there, if I keep it at zero it doesn’t do anything.
Almost there.
just select all the vertices of the bigger cube( which makes up the walls of your room) in edit mode (tab key) and flip the normals by pressing W and then number 9. I think that may help light your room up.
That’s right, yup. At the moment the normals are set outside the cube, like you’d normally have. However, since you’re inside the cube this time, the normals need to be on the other side (inside).