[Gdal-dev] OpenEV Questions

[Tyler Mitchell]

> Can I use OpenEV to (1) load a png file, (2)interactively supply the
> georeference info, and (3)export it as a geotiff?  Its the (2) part I can't
> seem to accomplish.

As far as I know there is not on-screen method for doing this, but it 
certainly isn't too difficult with a little bit of semi-manual work.
Open two OpenEV views, one with the unreferenced image, one with the 
geo-reference base you want to use.  Move your cursor over the non-referenced 
one (let's call it image1), record (read: write down!) the pixel x,y values.  
Then look at the same location in image2.  Write down the geocoordinate for 
the pixel.  You should have four numbers for each location you want to pin 
the image to.  And so on and so on.  Then use gdal_translate to translate 
image1.tif to image1_georefd.tif but adding the -GCP parameter for each set 
of coordinates.  Like so...

gdal_translate -gcp 1 1 500000 5000000 -gcp 200 400 550000 5250000 image1.tif 
image1_geo.tif.

Then you probably also want to run this through gdalwarp - which is a python 
script.  This will actually modify your new image, warping it as best it can 
to your new world!

Isn't currently working in my setup for some reason, but if you can handle the 
command line usage of those two utilities, you'll have a lot of raster power 
at your fingertips.

Tyler