Some differences when opening georeferenced imagery between QGIS and ArcGIS
Just did some minor testing after trying the Georeferencing toolbar in ArcGIS to create some world files (.jpgw, .pngw, .ecww, .tfw, etc.) and wanted to see how these two GIS suites treat the result. Normally I use MapWindow GIS to georeference aerial photos but its Image to Map Image Registration Plug-in is very slow and has some strange bugs that might deserve another blog post. The aerial photos were received from the provincial agency as MrSID files and were converted to ecw using IrfanView. Neither the original SID files or the ECW files had embedded projection information. In ArcGIS, I used the georeferencing toolbar and added five control points then chose Projective Transformation rather than the default Affine 1st Order Polynomial method to transform the raster. Upon clicking Update Georeferencing (Save the current warp to the dataset) from the toolbar, two files are created with the same name prefix as the .ecw file but with different extensions. They are photoname.ecw