Hello fellow renderers! I'm posting this today to show an important issue I'm having with displacement. I've had this problem across several projects where lap siding or shake is needed. In both cases, I get what is shown in Image2.jpg. The bottom edges of the shake are very bumpy and causes shadow irregularities as well.
To explain further, Image1.jpg is a test from using the corona_mat-shake_siding1.zip max file supplied. (However, I changed the displacement map to follow a straight edge siding - the map used is called shake_uneven_disp.jpg) I got it looking very close to what I wanted with the closeup shot. When I first opened the max file, I did a test render and came up with what's showing in WaterLevel.jpg whereas the test render that came with it, FoundOnline.jpg is how it should look. It took a while to figure out that the water level was causing the gaps in geometry. Setting it to 0 was what fixed it which is confusing to me. Once applied in a real world setting and the camera pulled back, the quality degrades heavily. In Image2, I was trying to find a solution by creating a simple plane object in front to see if maybe it was my model that was causing the issue.
I tried setting the subdivide on my home to 1" which was nearly 1 million faces total and that didn't do anything. In fact, the plane object had 1 poly and looked the same. I also tried upping the resolution of the displacement map to be 5000p wide which also did not work. When I started messing around with the render size, I started getting better results but that doesn't work for two reasons. 1: The edges are still jagged which won't be appealing to my clients and 2: The size it would take to look good enough is far beyond a typical size. Most renders are 1280x720 whereas it would likely need to be at least 20,000 wide to get cleaner edges.
StandardSize.jpg shows the exact same material as Image1 but in the real world setting. I get the problem when doing regular lap siding as well where the displacement falls apart when the map has a hard cut from black to white. At least with that I can model it in a pinch but it's not so easy with shake. Unfortunately I had to revert back to Vray in order to do these single family homes which is a bummer because Corona looks so much better.
Thank you for taking the time to review over this problem. If it's something I'm doing wrong on my end, please let me know.