In mtoa, using the closest filter for a Z AOV, I find that Z values are only written for alpha values above some threshold (about 0.15) which makes sense in a general scene with lots of overlapping stuff. In my case I am solo rendering objects and need Z values for any pixel that has non-0 alpha and I am doing a sort of back to front "over" composite in post. I can dilate my depth buffer for each "layer" with some simple extrapolation logic but am wondering if there is a built-in way of achieving this within the Arnold -- where the ground truth information is available and be dropped as I understand it.
First of all, is my understanding correct that there is such a threshold? And secondly, is there a way of controlling this threshold? I ask all of this because it is possible that my z-values are bucketing but my z-range is reasonably tight (about 0-215 and then normalized) and I'm using 32-bit floating point values to represent the depth. Also, I see depth values that are 0.00025 different from the one in question so I do seem to have the z resolution. I feel pretty confident that I have enough depth resolution so am looking at this as a threshold issue.
