Hi Andrew,

After examining the issue, it looks like vertices will need to be tagged – as coastal, inland, or at sea; we’ll include several DEMs so that the sim can pick which DEM is sampled. This should allow for correct “flat” water and eventual 3-d water effect.

LOL so the fantasy land is Mordor. 😉 I am assuming that an in-sim DEM must scale up at _least_ as far as MeshTool does now: 10801 x 10801. This is still only 10m though. On the other hand, 1m vectors will blow up MeshTool; you need to simplify!

In the long term I think we’ll finally break the 10m limit using raster data, not vector…

That really IS the case for NZ… the SRTM data is dreadful in places, an SRTM-resolution DEM based on the vector survey data is available… but since the vectors have about a 1m horizontal resolution, they win. Especially somewhere like, say, the Waimakariri gorge, which is only about 25m wide (and around 50m deep) and therefore cuts right between the SRTM data points.

Seems to me that there’s some potential for tagging triangulation edges and faces as ‘don’t use the DEM for me, just interpolate the tri’, which can be set on areas where high resolution data exists.

Are you planning on supporting higher resolution DEMs? That would be another way around the issue.

Well that’s an easier case…we can simply “rasterize” the water MSL from the polygon _into_ the DEM, reconditioning the DEM to match the vector data. 🙂

And..what fantasy land do you live in where the vector data is more accurate than the DEMs? 😉

Hmm… but in the cases where the vector is more reliable than the elevation, it would be really nice to be able to say so. Can we tag the geometry somehow, so we can say ‘this edge is nearly flat, keep it so’?

Yes. Xp10 will run all v9 scenery.

Will XP10 still support XP9 DSF? A real blow if not, as Andrew’s scenery adds significant fidelity to NZ.

The height ma does completely describe the terrain shape, but the triangulation tells us what terrain type goes in which places, including land-vs-water…thus the triangulation tells us the coastline!

This might require a separate post. Short version:
– Meshing is fast enough to run in background – no need to cut tile size.
– The entire part of DSF generation after the mesh would have to move into the sim too though, since that stuff depends on the mesh. That’s too much time and data for the sim.

Hrmm….that’s a damn good question! I just realized that the RF changes to “apply elevation later” in X-Plane effectively break any water flattening code in RF (which act on the triangulation). Well, now I’m really glad I didn’t solve the climbing water bug first (it’s still on the v10 DSF todo list).

One thing I had looked at, at least briefly, was letting the mesher just “mesh everything” and then changing the land/water status of coastal triangles by slope. When there is a conflict between vector and elevation data, the elevation data is often more reliable, and this technique gives you a coastline that is “where the DEM runs through 0 MSL.”