> Quote - Can you make it thicker at the top or bottom?

Well, yes... with some node knitting, using the P-Node to control DepthCue colour.

This shader applies DepthCue from a given minimum height upwards - the opposite of a ground fog, I suppose. It's okay for proof of concept, but not very convincing.

For some reason I'm getting darkening of the original (non-DepthCued) render at low heights and greater distances from the camera. I'm clamping the DepthCue colour to prevent it going negative below the minimum height, so i don't really understand why it's doing this.

More work needed... but not now.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)