We've been busy working on a number of features related to planet editing.
One of them is Snow -- players can paint snow onto terrain or props (it can cover trees, roads, houses -- if you want). Like with everything in Traverse, this is fully networked, so multiple players can edit and see each others edits at the same time.
The tool examines geometry where it is being painted, and replicates it with a distance offset, maintaining the normal vector of triangle. Depth of snow is one of the parameters players can change. Collision is also controlled via 'packed' flag, so you can choose if you collide with it, or walk through it. We will have a hard cap on maximum number of polygons of snow per planet, to ensure accidental overuse doesn't affect performance.
Rendered object is split in tiles (31m x 31m) which seems to give us good balance between number of vertices per object, and number of occluded objects in scene.
Like all other props, snow color can be changed, so it can be used for other purposes -- third screenshot shows how we used it as grass. You can even change color on per-tile level, for multiple uses (eg snow on mountain peaks, grass in some areas, brown mud in other..)