When you assign a coordinate system in Map or set the Zone in LDT
Drawing Settings, all you are doing is defining what the coordinates in
your drawing represent as relates to Lat/Long as transformed by the
chosen projection system. This also allows you to bring in other data
(DRG's, DEM's. orthophotos, tax map parcel data, etc.) that may be based
on a different projection (NAD27 vs NAD83 for example).
When you query a Lat/Long of a point ion your drawing, the coordinates
are gleaned and then projected to Lat/Long via your chosen projection.
As you can see by the rather long lists of available projections, it is
absolutely critical to make sure your data is set correctly and that you
know exactly what system was used for your attached data, if any.
If you have Lat/Long data for a set of points, in Survey >> Data
Colletion/Input >> Control Points >>Latitude/Longitude you can set
points directly from their Lat/Long and they will be converted from LL
to NE coordinates based on your current 'zone' or projection system.
This is the only way I'm aware of to manually input LL data into LDT.
--
Karl Fuls PLS
Autocad AEC Training and Consulting
Assistant Moderator - Autodesk Discussion Groups
grim wrote:
> No angles. They are GPS'd sample points. This actually brings up
> something I've always been curious about. Under "assign coord
> system" in map, you can set up your drawing to be in Lat/Long. How
> does Autocad deal with Lat Longs? Does it convert deg/min/secs to
> decimal?