Referencing a dwg file to an ortho image

Brian Harvey

Folks,
some help here please.
I have a geotiff image of a resort property, and client needs to overlay image with existing CAD vector drawings. The dwg have no spatial data.
What would be the best way to do this and end up with a referenced vector layer ?

Thanks

Brian

samknight

Hello Brian, if you first load your GeoTiff, then load your CAD layer, the CAD layer will likely show up very far away from the GeoTiff using the drawing's own coordinates. Under the Overlay Control Center, you can right-click on the CAD layer and select the top item in the popup context menu "RECTIFY-Modify Layer Position/Projection (Re-Rectify)". You can then use the Image Rectification tool to apply valid GCPs to the CAD layer using the GeoTiff as reference. Once you've got the drawing where you want it, you can save your GCPs under File (a good idea if you might want to edit them later), and OK out to the main map where you should hopefully see your CAD layer overlaying on your GeoTiff.
Regards,
Sam Knight
Director of Product Management
Blue Marble Geographics

Camron70

Once you've got the drawing where you want it, you can save your GCPs under File (a good idea if you might want to edit them later), and OK out to the main map where you should hopefully see your CAD layer overlaying on your GeoTiff.


______________________
watson