Unknown Coordinate System

[user]

Hello, I am new to GIS. I have been assigned to take a picture of our pipeline (which was created in AutoCad) and change it to a shape file for editing. However, the file that I have has an unknown coordinate system. Will CAD2Shape allow me to specify the coordinate system? Thanks!

[GuthCAD Software Support]

The current CAD2Shape is principally just a straight converter. I.e. whatever values (coordinates) are in the CAD file, will be transferred to the shape file.

You would need to georeference the drawing either on the CAD side (e.g. in autoCAD), or on the shapefile side (e.g. in ArcGIS).

Having said that, the software does support some basic coordinates conversion. They are:

(1) The common projection: UTM WGS84/NAD83 to Lat/Long
(2) The option to use UCS coordinates in the CAD file.
(3) options 1 and 2 used together

Use option (1) if the CAD drawing is in the UTM WGS84 / NAD83 projection in whatever units, to convert to Lat/Long degrees.

Use option (2) (UCS = User Coordinate System) to convert a local offset to world coordinates. The UCS is defined within AutoCAD.

However the fact that you say you have an 'unknown coordinate system', is probably the main hurdle, irrespective of what software you use. You need to georeference the drawing. You need to find out something about what coordinates the drawing is in. This means relating values in the drawing to known points in a known coordinate system (e.g. points on a map), and also to knowing what units the drawing was drawn in.

Can anyone recommend a good straight-forward guide to georeferencing?

thanks,
Paul G