Bright then dark spots at edges of room

[gazbo]

Hey all,

 

I'm working on my first interior and am really pleased except that the edges of the room seem to alternate between bright and dark spots which really ruins the image.

 

I did post this problem at 3dbuzz where I said I'd fixed it by enlarging the radius of the photons, but when I rendered at higher res the problem was actually still there.

 

Also any tips on the rest of the image more than welcome.

 

Cheers

[gazbo]

Hey Brian,

 

Yeah, thought I'd sorted it before but no cigar. After what you said at Buzz I tried remodelling the walls as separate extruded lines but it made no difference. Driving me mad this one.

[gazbo]

Here's a render final gather only, the problem does still show up. Do I need to turn off the sun to know whether it's photon related?

 

The room is modeled as a single editable poly which is all closed up, and seeing as I tried it as separate walls/ceilings with the ceiling and floor coming to the outside edges of the walls I'm presuming that isn't the problem. I really appreciate your help on this, it's for my final project at uni and I really need it to be good.

 

BTW, are you originally from manchester, I thought from your voice you were from sheffield?

[gazbo]

Well here's another render with just fg and the sun turned off and there are dark patches which correspond to the problem areas in the final render.

 

The question is what can I change? I've tried changing the final gather presets, and there isn't a lot to change in the skylight settings.

[gazbo]

OK, took a while longer to render, what does this tell us then? Hopefully that I need to push one button and all my problems will be solved, right

[gazbo]

This is it with the sun & gi back on.

[Justin Hunt]

The Max radius seems very small, try this

 

Create a sphere around the room so that it just touches the outer wall, read off the radius. Get rid of the sphere and plug that radius value into the Max sampling radius slot. you may need to tweek the number.

 

Other trick is to place a box around the model that encloses the room. Keep the openings where there are windows (to allow the sunlight in). Shell the box to make sure it is solid and all the edges and vertecies connect. This box will capture any stay photons and block photons where they are not wanted.

 

For the sun values, Keep the multiplyer at 1. Try a little Have (2 or 3) to diffuse the sky light. Turn off aerial perpective. Rather use exposure control to brighten your sceen.

 

JHV

[gazbo]

Nice one! At first increasing the radius got rid of most of them but made a huge light bleed from the wall of the right, then the box round the room got rid of it.

 

What I don't understand is the room was modelled as one editable poly that was already closed, I did an STL check on it and there were no holes or overlapping faces, edges or vertices, so how was light leaking through????

[Justin Hunt]

Is an old problem with photons, then dont particularly link single sided polygons and sometimes very thin double sided objects. Making the surfece double sided (turn off backface cull in the A&D material) sometimes fixes this, but it seems safer to give a decent thickness to the walls, floors and ceilings

 

JHV

[gazbo]

Cheers for your help guys, here's the final image anyway. I turned off backface culling and that got rid of the last few problem areas. Thanks again for your help, it really is appreciated.

 

Also Brian any news on the exterior mental bout max project?

[Justin Hunt]

Very nice, a few things to fix but nothing to worry about. Except for the flare;)

 

JHV

[gazbo]

You're right the flare is cheesy, they were all the rage once upon a time weren't they. Mind you so were powerpoint presentations.

[Justin Hunt]

very retro

 

JHV