These coordinates describe the geographic footprint of the 3D terrain model exported from demo3d.
Two coordinate systems are shown: WGS84 (universal GPS standard) and Lambert-93
(the French national grid used in the source data).
Centre
The geographic centre of the model's bounding box, in decimal degrees (WGS84). This is the point Google Earth and the IGN map zoom into by default.
Format: latitude° N, longitude° E
SW / NE corners
South-West and North-East corners of the rectangular footprint. Together they define the bounding box of the printed terrain model. The Lambert-93 values are the original coordinates from the demo3d export file.
Lambert-93 is a metric projected CRS (EPSG:2154) — values are in metres from a French national origin.
Footprint size
Real-world dimensions of the terrain covered by the model, in metres.
Formula: footprint (m) ÷ scale = print size (mm)
Base altitude (z_base)
The lowest elevation kept in the model, in metres above sea level (NGF-IGN69 datum). The terrain is "sliced" at this altitude to create a flat base for the physical print.
Scale
The ratio between the printed model and reality. Horizontal and vertical scales are equal (Z scale × 1.0 = no vertical exaggeration).
Z scale
Vertical exaggeration factor. × 1.0 means the relief is true-to-scale — heights are neither stretched nor compressed.
Coordinate systems
WGS84 (EPSG:4326) — global GPS standard, used by Google Maps, Google Earth, and this map.
Lambert-93 (EPSG:2154) — French national projection, used by IGN and in the demo3d source files. Conversion performed using the pyproj library.