I'm trying to form a mosaic from two overlapping images of an old tithe map. I've used the georeferencer plugin using one of the images as canvas to generate a modified version of the other. I then used Raster>Miscellaneous>Merge. This generates the following commandline:
gdal_merge.py "/home/ian/Maps/Stubbin/1801 map Stubbin prt 1.JPG" "/home/ian/Maps/Stubbin/1801 map Stubbin prt 2_modified.jpg"
This gives an error:
ERROR 1: Attempt to create 2768x-1659 dataset is illegal,sizes must be larger than zero.
This seems to be related to the fact that image metadata for the original images shows the layer extents as 0.0, -1651.0 : 2339.0, 0.0 and other digital camera images also have -ve extents.
How do I work round this?
Platform is QGIS 1.8.0 on Debian Squeeze 64-bit.