Hi again everyone, the image I have attached is a high quality render with global illumination etc. The objects are on a wall, and they are lights faciong up and down, with globes inside them set to around 600% strength, to make the walls light up nicely. I also have a blobe in the room set to around 70% to give some ambient light. I can't work out why I am getting those sections of light right behind and beside the lights' shadow on the wall. Its really irritating me. I want to just have a nice dark shadow there, but instead I am getting these yuk sections of light. How can I avoide this? I still want to use GI Rendering. Scott Richardson

Also, attached is an earlier render, which looks nothing like what I wanted, without Global Illumination etc. It has less of the light behind/beside the lights tho. Scott

Scott, looks like you have some bleeding from the internal lights. I'm going to make an assumption that they are spheres with a glow scaled to 600%. If the sconce/fixture has any open facets along the way, that would cause the bleeding. If not, I would recommend making the globes in the fixture smaller. Size is not an issue in indirect glow lighting and if any of the glow facets are intruding on the fixture that would also cause the bleeding we are seeing here. Ken

there are no gaps in the outer fixture, so it must be the globes. I have NO glass spheres around the globes... just the globes themselves in there. I will shrink the globes and add some spheres and let you know how I go. Thanks Scott

It looks like caustics. There was an earlier thread about this; will try to remember which one it was.

yeah it looks like caustics to me too.. but.. alas.. caustics is turned off, and nothing is made of glass here. I am guessing that it is the radiosity/global illumination that is causing it. If you look at my 2nd image, you will notice small highlights from lights, but in the GI one, the lights are the really bright bits that I dont want... its a mystery I tells ya. Scott

Scott, If you've got a free few, try to post a wireframe of the image. Should only take a few secs to render. This will give us a good idea of how the scene renders out... Ken

hi guys... have attached some more images. I have shrunk the globes, added spheres, and done a wireframe shot. I have overlayed my questions on the image there. Scott

here is the image

Turning off Interpolation should help this. Mark

thanks Mark.. rendering agai now.. will let you know how it goes Scott

I believe the manual talks about this in the section talking about interpolation or global illum. It say that bleeding can occur if the object's thickness is thin... But also I think turning interpolation off will help - I was getting boxy artifacts that were eliminated when interpolation was off. The image took longer to render however. Good luck.

Yup! it fixed my problem. thanks guys, glad I had you guys to help me out just for interest... why on earth does light bleed through a solid (thin) object? Is that a problem with the rendering engine? Scott

When the program is allowed to interpolate (round-off numbers), instead of specifically calculating the light paths, it does a "close-is-good-enough" calculation which saves time. Basically, it puts the light in the correct general area. On many occasions, the time savings is worth it. However, when you have thin walls on an object the "close-enough" calculation can allow light to pass through objects - especially when the intensity is cranked up.