Is there a DEM height data margin?

Hello to all your fantastic MSFS/Asobo team :wink: First of all, thank you to
have included the polygon definitions in the scenery xml file instead of in
separate ESRI shapefiles. I can now generate dynamically my own exclusion and
terraforming polygons. that’s great ! I am now playing with the DEM height
data to dynamically generate height data maps inside the scenery xml file. To
do this, i made a python script to import my 3D tile in blender, create a grid
under this tile, then ray cast from the grid the bottom of the tile to create
height points. Here are some examples:

It seems to work as intended,
except that the generated height data seem to be 50 meters below the sea

If i add 50 meters to my height data, it seems to be correct:

So my question is: is there a specific margin for DEM height data (for
watermasking purpose, for instance) ?

Hello Thalixte, This depends on your DEM data source. The value of
18.018150210380554 m referred to the geographical coordinates latitude =
“48.6309814453125” longitude = “-2.051696777734375” is the height (h) referred
to the ellipsoidal height, to have the orthometric height referred to your
point of interest you must add +/- the Height on the Geoid (N).
bin/GeoidEval?input=48.6309814453125±2.051696777734375&option=Submit) Inside
the SDK documentation you will find this:;=geoid
altType This is used to determine the referential for the alt field. GEOID

Thks a lot for this answer. I understand now the difference i obtained.