Assigning Geographic co-ordinates to shapefile with

waldo

I had created two street level shapefiles maps using another GIS app (mapwinGis), by tracing the streets on a satellite/aerial image and adding the resultant lines to another polyline shapefile layer.

I didn't georeference and assign a projection to the initial jpeg images and so the reslutant shapefiles cannot be positioned accurately and do not merge properly in Global mapper....

Even when I assign a projection to the shapefile it doesn't position accurately because I think the individual shapes vertices do not have any corresponding lon/lat co-ordinates.

Please how do I assign Geographic co-ordinates to my shapefile (like each vertex having a corresponing lon/lat co-ordinates), using Global Mapper.

Any assistance will be greatly appreciated. Thanks.

global_mapper

You can geo-rectify any loaded layer by opening the Control Center, right-clicking on the layer, then selecting the option to Reposition the layer.

Let me know if I can be of further assistance.

Thanks,

Mike
Global Mapper Support
support@globalmapper.com

waldo

Your explanation was really helpfull but I still ran into a little problem...........

After rectifying the shapefile I then clicked "apply" and then "OK"...closed the dialogue box but my map had dissappeared.

The chosen projection for my shapefile is
PROJECTION=(Geographic {latitude/longitude})
DATUM= (WGS84)
PLANAR UNITS=(Arc Degrees)

If I change the Planar Units to any value other than Arc Degrees or Grades(French Angles), the shapefile dissappears.

Also when rectifying the shapefile, I noticed when I click on a point in the Reference images view the accompanied coordinates are in the Groung Control Poins Entry box are in degrees, minutes and seconds and that is the format I follow when putting in the right coordinates. But upon clicking the "add GCP to list" button, the resultant long/lat values in the Ground Control Point box below are in degrees and when I click apply and ok, exit the rectify dialogue box, the map disappears.

I believe this two scenarios are tied together. How can I rectify my shapefile properly and have it appear after the rectification process?

Your help will be highly valued.

global_mapper

I think that you may just still have a view on the old coordinate location once you rectify your map with the new coordinates. Just press the Home button on the toolbar to zoom to the full extents of the loaded data and see if that works better.

Let me know if I can be of further assistance.

Thanks,

Mike
Global Mapper Support
support@globalmapper.com