georeference/rectify maps
redbeard
Global Mapper UserTrusted User
I know you can take a non geo image and make it a geo image. But It seems clumsy in all the packages I've used (including GM, its about the same as the other offerings). Here's some ideas which may work for stuff that has standard spacing (and perhaps make Global Mapper better than other packages).
Have a window where you can overlay grid lines of user defined intervals (every 7.5 minutes, 30 minutes, degree, 2 deg, whatever). Set the projection/datum. Then zoom in to the area where you will be working.
Load an image, and have it temporary placed under the grid where you zoomed in to.
Use a 2 click system to place points without typing in coords. Click once on the image, say a corner of neatlines that states the coords. Click a second time on/near the grid and have the point where you first click snap to that intersection of the grid, automatically putting in the coords.
Have the zoom tool avail and zoom out and go to the next corner and place a second point where you need. Repeat however much you wish.
When done, hit save, and have it create a new image in whatever format you want (or just a world file).
Does this make sense?
I think a system like this would be a fairly quick and easy way to reference an image. If you need clarification just reply.
Just a suggestion.
It would make my life easier as I find sets of maps that are not georeference, say from the nice (but not GIS minded) http://www.lib.utexas.edu/maps site.
Have a window where you can overlay grid lines of user defined intervals (every 7.5 minutes, 30 minutes, degree, 2 deg, whatever). Set the projection/datum. Then zoom in to the area where you will be working.
Load an image, and have it temporary placed under the grid where you zoomed in to.
Use a 2 click system to place points without typing in coords. Click once on the image, say a corner of neatlines that states the coords. Click a second time on/near the grid and have the point where you first click snap to that intersection of the grid, automatically putting in the coords.
Have the zoom tool avail and zoom out and go to the next corner and place a second point where you need. Repeat however much you wish.
When done, hit save, and have it create a new image in whatever format you want (or just a world file).
Does this make sense?
I think a system like this would be a fairly quick and easy way to reference an image. If you need clarification just reply.
Just a suggestion.
It would make my life easier as I find sets of maps that are not georeference, say from the nice (but not GIS minded) http://www.lib.utexas.edu/maps site.
Comments
-
Thank you for the suggestion. What you are describing is pretty similar to how the reference map view already works in Global Mapper when rectifying imagery. You could setup a grid in whatever projection that you need with the desired spacing in the main map view, then when you go into the rectification dialog you will see that grid (plus anything else loaded in the main map view) in the reference image view. You can then simply click a location in the map to reference, then click the corresponding location (like a grid line intersection) in the reference map view to fill in the coordinates, then just add the control point. Just repeat for however many additional points that you need and you are done.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com -
I did some searching, but can Global Mapper create graticules? I didn't find an answer.
I did find some data for lat/long lines here http://www.naturalearthdata.com/downloads/10m-physical-vectors/ at the bottom of the page, which will be useful.
I guess one part of my suggestion would be cool for v 12 or 13 is the snap to vertice/intersection/point of vector data when registering images.
But anyway, I'll try later tonight the method you described.
Thanks! -
Yes, you can easily create graticules over loaded data by setting up the grid on the General tab of the Configuration dialog.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com -
So, I just went and tried it. I works exactly like I was thinking. Even the snapping thing. So scratch that off any list. Amazing. Sorry for the extra noise on the forum.
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