I am serving several raster images with Geoserver using ImageMosaic and PostgreSQL to index data. The files are stored in the file system in GeoTiff format with EPSG:4326 and a pixel size of 2.7e-5 x 2.7e-5 arcsecond/pixel.
When I open this file in QGis with its vector shape definition, they match up perfectly in any OTF configuration, as it can be seen here:
The problem is that when the image gets served in Geoserver it seems to get skewed or shortened in the vertical axis, as seen here:
Here's another example. The raster image has a 1.5 pixel buffer that is why it should overflow the boundary, but the reprojection is just wrong.