You're working with some pretty extreme displacements and they are crossing render tile boundaries. The cut-offs occur at the edge of a render tile (work region for the renderer). Default optimizations in the renderer can cause issues in these cases, but they provide a performance benefit under normal circumstances. Fortunately there's an easy fix, at the cost of render time. Just increase Displacement Tolerance in the Planet node. Try a value of 1.5 or 2. As you increase it, go in relatively small increments, i.e. don't crank it up to 5 or 10 right off the bat; in fact values above 3 or 4 would be strongly discouraged, and a value of 2 should generally fix most such problems.
- Oshyan
