Creating a fluorescent light for render

can someone explain the reason why there are spots and bursts in this render . I tried to create a fluorescent
light by applying emissive layer to the light material but once i render I get this.

This is not directly a SketchUp problem. It has to do with your rendering application. What rendering application are you using?

This seems more an issue with your renderer settings than with SketchUp. What renderer are you using? Maybe someone else here knows it?

Dave beat me again!

I used vray for rendering. I added an emissive layer to the light material and this is what appears

I can’t remember v-ray in detail as i switched to Thea, but I think you have to increase the “sample amount”, or overide settings to allow it to render longer? Below is a link to some solutions within v-ray.

Also is the fluorescent tube itself an emitter? or did you put the emitter inside a glass tube? When it’s blown out like this and there’s no chance of seeing the reflection of the glass tube there’s not much benefit as having the light pass through the glass overly complicates the render with time and could make the dot problem worse? If it isn’t already I would make the simple tube with an emitter property without glass or reflection.

As others have mentioned, you will have less trouble finding the answer on Vray forums than here because your issue or related to the renderer.

With that said, your issue is because you are not really meant to light the scene with a material’s emmisive layer. Emmisive material is messy, noisy, limited controls. On the contrary, emmisive layer on a material well immediates how lights are observed. You should use other standard lights such as sphere, omni, rectangle lights to light up the scene and make them “invisible”.

I hope this makes sense.

Most modern renderers are quite capable of doing this, but you will need to set render quality parameters significantly higher and prepare for much longer render times compared to renders using only predefined lights. Otherwise the resulting images will be strewn with artifacts. I have also noticed that this approach works better if all materials used have a texture and the scene has no “basic” materials.