Earthanchorpoint in mm or meter instead of Long et Lat

how to convert as accurately as possible (mm precision) from X Y coordinates and elevation to longitude and latitude.
With the earthlanchorpoint function or in the options I have no choice
this will allow me to export in ifc with the correct geolocation

90° = 10^4 km = 10^10 mm

You cannot specify the Earth Anchor Point in mm or meters, because it represents a point on the physical globe — or more specifically, a relationship between your perfectly straight XYZ coordinate system and a real position in space. Where on earth is “20m, 50m”?

IFC’s geolocation is the same thing, albeit a bit more complicated. It is a mapping between the model’s XYZ coordinates and a real point in the world, utilizing a CRS (coordinate reference system) which defines such a mapping.

Only after you have established a mapping (and a projection) between a latitude/longitude and a model location (typically 0,0,0), can you then convert between lat/lon values and meters.

You’ll also need to understand State Plane coordinates and adjust your model accordingly, but here is a link to a converter:

we you lambert 93
i know the differency between sphere coordinate and plan like UTM
but coordinate in lambert 93 or lambert 2 is not exactly the same

can you give me an exemple, if i’m in french we use lambert 93 or lambert 2
and i have NS xxxx meters and OE xxxx meters

You’ll have to use a converter to go from Lambert to Lat Lon:

If you are able to use Grasshopper, the Heron add-in has a Coordinate Transformation component that could get you what you need. Note, the Rhino Earth Anchor Point was set to Paris and the model units are in feet for the example below.