Here is a quick down and dirty on how to make a glow dome for rendering with raydiosity. Nothing really special here many of you may already know how to do this but here you go anyway.

I started off with a chrome sphere in the center grid and I turned on the ground plane in the "environment" dialogue box under the "Ground" tab.

Next we need to make the dome that will be the light source. Use your pen tool and make an arch on the ground plane like this

Now we will lathe the arch into a upside down bowl. Like so...

Now with the dome made I drop a camera in so it looks like this. Please note that the camera is inside the dome. If you have trouble positioning the camera inside the dome, move the dome to the left or right from the front view then position your camera and move the dome back.

Now let's make our glow map. From your "Resource" pallet click on the "new" button at the top left and select "surface texture" from the drop down. Name your new texture "glow". In the glow map area all you need to do is load an image file so the light will be varied and not uniform. I loaded a stock photo of a mountain scene so there would be some contrast in the lighting. Then push up the glow value, this acts like a dimmer switch in your house, the higher the number the brighter the glow. The color is defaulted to white so your light source will have a white base to it. If you change it to blue then it will glow blue.

With a glow dome set up all other light sources need to be off. So let's shut off the default global light.

Time to render. Here are the render settings I used for this quick one. Keep in mind that raydiosity is ALOT more resource intensive on your machine. It may take a while.

There you go. Glow dome render down and dirty. I hope it helps.