Flat Cone

Both ambient occlusion and inner occlusion shoot rays inside a cone (like a wide spotlight). RichDirt supports flat cones. A flat cone doesnt shoot rays in the center. This is like a spotlight that is blocked in the center. See the image below. It shows a lane (gray) that is surrounded by grass (green). A standard cone with 90 degree versus a flat cone with 30 degree.

What is the advantage ?

RichDirt will hit the edge lane-to-grass because the grass geometry sticks out by 1 cm. The standard cone will miss these obstacles, because most of its rays don´t hit the edge. The flat cone on the other side, hits more of the obstacles. In the image below it uses 30 degrees. This could be -less- like just 1 degrees. Then nearly all rays would hit the obstacles.
What is it good for ? Whenever IO and AO would not see an obstacle. The images below show how it works when only AO is on. AO with a standard cone misses the edge. When to not use flat cones ? With displacement, with bias, with upslope.

A real scene that uses a regular cone. The edge is very short. IO is intentionally switched off so one can see a clear difference in the following images.

A flat cone of 1 degree (enter´-1´ in the UI to activate the flat cone). The flat cone hits much more of the obstacles - there is a nice and wide stripe visible. Also there is less noise, because more rays hit the edge.

To get an even nicer lane we add streaks (ao streaks on). Amount 100, washlength 0 to get maximum wash length. The size of the streak map is huge - 50 cm. This creates a nice variable edge on the lane.

To get a more subtle edge try ´amount 80´ and ´wash length 70´. This creates a wider and more subtle edge on the lane.


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