I want to improve the accuracy on an existing scanned image to match data that has been updated so that I can add it to our GIS. I import the legacy map as a TIFF file, rubbersheet it to lines that I created using AutoCAD Map which has a projection assigned and then export if as a GeoTIFF. This should be pretty straightforward, but I have a couple of problems.
- When I use the polynomial method of rubbersheeting the raster data is adjusted inconsistently and, while the image is improved, the lines are not moved to the proper location. However, I can export it as a geotiff and the image comes in at the correct location in the GIS.
- When I use the triangular method the raster data is pulled into the correct location, but the geotiff comes in smaller than the target area. It's as if the data were scaled somewhere in the transfomation.
How do I reconcile this problem?
Is there a way to improve the polynomial rubbersheeting to give me what I want?
What's up with the image size created by the triangular rubbersheeting?
Thanks,
J Edward Leavitt