Glad to see you’re doing so much with the metavoxel stuff! Needless to say, there are a lot more improvements in the pipeline.
First, the delay you’re seeing seeing on load is probably the download speed (or at any rate, that is a problem, even if it’s not the one you’re seeing). Since I switched to lossless compression on the terrain (which removes the compression artifacts we were seeing, as we were using eight bit JPG for both height and color data), we’re sending much more data, and we’re sending it through our own reliable UDP layer (as opposed to TCP), which may be relatively inefficient. The plan is to switch back to lossy compression at least for the color data, and also to cache terrain data to avoid resending. There are also some tweaks to be made in terms of adjusting the LOD computation (which determines both what gets rendered and what gets sent over the wire). You can see if metavoxels are downloading by opening the extended stats (forward slash, then click on the stats display) and looking for a download percentage under the metavoxel node counts.
As I think you discovered, the “Import Heightfield” and “Insert Spanner” (with type Heightfield) options now do the same thing; “Insert Spanner” just gives you more control over the transformation (allows you to rotate the heightfield, basically) at the cost of some convenience. With “Insert Spanner,” the heightfield starts out as a 1x1x1 (meter) cube, with the vertical range (0 to 255 for an eight bit import, 0 to 65535 for a 16-bit one) spread out over the vertical (Y) range. Scale scales everything at once, aspectY controls the ratio of Y:X, and aspectZ controls the ratio of Z:X. With “Import Heightfield,” the “Spacing” option controls the distance (in meters) horizontally between height samples (so, setting it to 1.0 with a 1024 height map will extent to about one kilometer). The “Height Scale” is the range in meters corresponding to the imported range (so, 1.0 would map 255 to 1.0 for an eight-bit import), and the “Height Offset” is just a Y offset in meters.
Aside from what I mentioned (fixes for download delays), my current project is coming up with a better solution for uniting the heightfields with the dual contour representation. Currently, the dual contour representation (generated piecemeal when you use the “voxel” tools like the Sculpt Brush) doesn’t quite align with the heightfields, and always uses a fixed resolution, which means that it’s very easy to overload the server by attempting to tunnel into a large, low-resolution heightfield. The plan is to use a more memory and bandwidth efficient format that combines both heightfield and voxel data and uses the same horizontal resolution for both.
Other things on the horizon are masks to control how different terrain textures blend together and baked lighting computation on assignment clients.