FSXA Correcting (many) elevated lakes in the Andes

[FlyingAxx]

Hi Axel.



Why not try Google Earth? The altitude is read as you hover over the terrain.

Dick

As I wrote in my first posting I already tried Google Earth just by hovering, but it looks like those lakes are seldom flat. The method Jim described, measuring a distance across a lake and look for an elevation profile after , seems to be at least a way finding a half the way fitting average.



This lake had been an example where the linear interpolation didn't work properly as the level jumped up and down by up to 14 m. I tried a path and upon the result I would suggest a lake level of 3459 m.

 

[FlyingAxx]

There is not much point in finding the true altitudes, they must be consistent with your mesh.

It is worth finding the true position and shape.

Indeed George, and for this purpose geo-tagged pictures made with Dick's tool "Rhumba Maps" are working wonderful in SBX that tends to crash sometimes (at least for me) when being treated with updating backgrounds. Very often the right positioning and shape helps.

 

[ollyau]

SlopeX and SlopeY must be present but they are ignored by Shp2Vec.

Well sure, shp2vec doesn't need it for anything; it's the sim that uses it. You can check TMFViewer and the documentation of the BGL format Patrick contributed to -- their values do get compiled into the scenery. Doug Matthews (from ACES) said the following about its use:

The Slope parameters are used for extrapolation of polygon vertex elevation onto the mesh grid where the vertex does not fall precisely on a grid point. Depending on the in-game mesh settings, the use of SlopeX=SlopeY=0 can range from imperceptible to very perceptible in-game anomolies. We would not have wasted the disk space, memory footprint and loading time if there was not a tangible benefit.

If you have achieved 3D polygonal water already, try just setting slope x and y to 0. See how it looks. These values are used for extrapolating flattening to nearest mesh points. At reasonable terrain setting it may turn out to be acceptable.

It is possible to just set them to 0, but there may be artifacts when doing so.

 

[rhumbaflappy]

If you make a sloped waterpoly in SBuilderX, and compile it, then decompile the CVX file with CVXExtractor, then look at the ESRI SHP file.... you'll see the slope info is extracted to the .dbf file. This means the slope is saved by SHP2VEC for use in the sim. Most waterpolys are 0 for the slopes as lakes are generally considered to be flat in the sim... though not true in real life.

Dick

 

[ollyau]

Most waterpolys are 0 for the slopes as lakes are generally considered to be flat in the sim... though not true in real life.

Do most hydro polys use a value for 0 for SlopeX and SlopeY even if the elevations of the vertices in the shape differ, or is that only true for the case where the vertices are all at the same elevation?

 

[rhumbaflappy]

In SBuilderX, you can set a variable altitude from a point with heading and slope towards that heading, and the slopex and slopey are generated. I believe simply setting points at different altitudes will not generate a slopex and slopey.

Dick

 

[FlyingAxx]

In SBuilderX, you can set a variable altitude from a point with heading and slope towards that heading, and the slopex and slopey are generated. I believe simply setting points at different altitudes will not generate a slopex and slopey.

Dick

Dick, if looking over the fence to ADE it seems to be possible just to set the altitudes of vertices. There is nothing else in the related XML, too and it seems the compiler can deal with it. In my experience it could be troublesome "bending" a poly with multiple vertices as this can lead to unexpected waves in the surface and sharp edges to neighbouring elements.