Elevation outside currently shown Earth scene

[Thomas-Lerman]

We have run into cases where we are drawing lines with shaders outside on the other side of the Earth (or close). When we go to that area, we find that the line starts off below the Earth surface and then spikes up. We are converting the GeoPoint clamped to ground (0 relative to ground) to makeAbsolute() then converting it to ECEF. It appears the makeAbsolute() fails and gives a bad elevation while the DEM is not loaded for that area, but seems to get it at some point for subsequent points. Any way of telling it to force loading of the DEM or something to get the correct elevation or other suggests?

[gwaldron]

GeoPoint::makeAbsolute samples the loaded terrain mesh (that's why it takes a TerrainResolver pointer). So if you are using it against geometry on the other side of the earth from your camera you are going to get very low resolution results since only a low-LOD mesh is loaded that far away.

If you want to sample the elevation data at a point, use ElevationPool:

auto sample = map->getElevationPool()->getSample(geopoint, nullptr);
if (sample.hasData()
    geopoint.z() = sample.elevation().as(Units::METERS);

[Thomas-Lerman]

And unfortunately, ElevationPool seems to be newer that what we have :-(. Any other suggestions for now? Such as finding out what the resultant resolution and/or LOD is?

[gwaldron]

Try the old ElevationQuery class.

[Thomas-Lerman]

Oh yes, of course. Thank you so much for your help.