Quote from: bigben on March 11, 2008, 04:30:06 PM
... Back later when I have something slick to show.
I lied
I has started a render with GI but I accidentally disconnected one of the primary rainbow masks which made the entire rainbow disappear
The pre-render took a long time.
Here is an incomplete render of the new, improved double rainbow. Detail 1, AA 2, GI 0,0. The primary rainbow has the original (theoretical) gradients.
The secondary rainbow has two extra tweaks;
The minimum density of each has been increased by multiplying the gradient by 0.5 and then adding 0.5 to the result
The black levels of the internal gradients (not going to the edges) have been shifted to the next secondary colour (red = 0 at cyan insted of green, blue = 0 at yellow instead of green, green = 0 at violet instead of blue).
The secondary rainbow seem to be holding together much better at lower densities and I may apply the second tweak to the primary rainbow before starting a render with GI.
I may have to extend the red and green black levels beyond the red edge of the rainbow to lighten the yellow as it's gone a little orange. See... I knew there was a reason for posting this... Stopped the render to apply the revised black levels to the primary rainbow and discovered that there were some old tweaks to the gamma of the gradients on the secondary rainbow. These would have been largely responsible for the reduced amount of yellow.
The gap in the primary rainbow looks a little odd although I'll have to reserve my judgement until after seeing a render with GI which will lighten the shadow. It's caused by a shadow, but the thin bit of rainbow in front of the shadow has disappeared. The difference in intensities is probably too great due to the depth of the rainbow (3km). Using a thinner rainbow would fix this... probably around 300-500m, although this would make it a little harder to position the rainbow.
There is no darkening between the two rainbows in this example, although I have a mask that can be used for this. This area will look darker anyway due to the lightening applied inside the primary and outside the secondary rainbow.