While importing toposolid, Snaptrude uses Mapbox to bring in the topographical data. Here is an explanation about the coordinate system used by Mapbox for the same. Mapbox uses the Web Mercator projection (also known as EPSG:3857) as its default coordinate system.
Projection Name: Web Mercator
EPSG Code: 3857
Units: Meters
Coordinate Axes: X (East), Y (North)
Coordinate Range:
X: approx. -20026376.39 to 20026376.39
Y: approx. -20048966.10 to 20048966.10
Geographic Coordinates (Lat/Lon):
When working with Mapbox GL JS or their APIs, geographic coordinates are usually passed as [longitude, latitude] in decimal degrees.
Internally, Mapbox converts these to the Web Mercator projection to render the maps accurately and efficiently on screen.