Geographic Projection In AutoCAD

Hello all, I am new to AutoCAD but have backround in GIS-MapInfo. I have a bunch of AutoCAD drawings (a local fiber network) that I need
to convert to GIS format, and that part I know how to do. My problem is that I am trying to determine a co-ordinate system the CAD files were done in. I dont know how to accomplish this. I have AC-2008, and I tried looking in, "View-Render-Light-Geographic Location" I cant seem to find any other place where I can view the existing, if any, settings.
Thanks in advance for answering My questions
thanks much
Steven
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Acad dresses up generic Cartesian coordinates to look like other units. The drawing's author sets this up when they start a drawing, but it can also subsequently be changed by anyone, creating all sorts of havoc, since a unit is a unit. A 'unit' van be an inch, a foot, millimeter, meter, mile, etc., so if you change them without scaling the model up or down, you've just changed the real-world size of everything in it.
Unless someone keyed their coordinate system to some other 'real world' location and orientation, I'm afraid you will have to devise a way to do so.
--


MichaelB
www.michaelbulatovich.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

How 'local' are the networks? Buildings, city blocks or larger regions? Maybe start by looking for an object in the drawings which has a known dimension in the real world and do a 'dist' on it? Might be difficult with fibre optics ... One of my sons did fibre-optic drafting work using ACAD for Telstra in Oz - I'll ask if there are any conventions.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Wouldn't be surprised if they weren't to linear scale.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Save As dxf and drag the dxf file into a text editor to read what units are being used. You can corelate what you read with what is in the dwg file and take it from there.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.