Dear all, i'm currently struggling to produce a simple, georeferenced image to use in Arc and also export for use in other programs like 3D Move and Google Earth. What i have is a simple, scanned jpg of a fieldmap overlay that my old Phd supervisor gave me. It's ~56mg and has no other metadata stuff attached. What i need to do with it is to create a version of the image that I can open in other programs and have it locate the image correctly so that I can then add and edit data, and then export that data into a database.
My main problem is that the basemap on which the mapping was done is in NGO1948 Zone 5. I have added the jpg to a fresh project that has been configured to use the projected NGO1948 zone 5 coordinate system, and built the pyramids with no problem. I have used a number of control points around the image and given them their values as taken from the grid system on the map. However, I can't then convert the coordinate system to a system such as WGS84 or similar that Google Earth and the other programs can understand. When i change the coordinate system to WGS84 (or any other), the image is altered, but certain marker points are not in their correct locations. For example, there is a town on the map, which Google Earth locates at 17°48'19.87"E 68°44'48.59"N, whilst Arc shows the same town at roughly the same Easting but at ~58°N, so the conversion is clearly going wrong somewhere.
My second problem is that when i export the map, the GeoTiff i produce doesn't appear to have any data embedded (correct or not) to tell other programs where the image should be located. The GeoTiff is also very low quality, so that when i zoom in in GE to look at the data points on the map, the resolution is too low and the data has been lost. This is using the "export map" option in the file menu, and then saving as tiff with max JPEG quality and "write GeoTIFF tags" selected.
Many thanks for any help!
