I am attempting to make a digitised version of an 1848 cadastral map of Siemiechów, Poland (Lat 49.853, Lon 20.902). I have 44 map images that I aligned and assembled into a large mosaic. I used the QGIS raster georeferencer and a selection of latitude/longitude data for road intersections to prepare a georeferenced TIF file. I used various CRSs (see below). I am using QGIS 3.22.14 desktop.
No matter which CRS I choose, the georeferenced on-screen image is squashed, that is, the north-south dimensions/distances appear much smaller than east-west. This is a problem with how the raster is projected. I have tried:
EPSG 2178 – ETRF2000-PL / CS2000/21
EPSG 3035 – ETRS89-Extended /LAEA Europe
EPSG 3857 – WGS84 Pseudo Mercator
EPSG 4326 – WGS84
ESRI 102176 – ETRS_1989_UWPP_2000_PAS_7
I checked my work by snipping map images from Google and OpenStreetMap and georeferencing them. The same substantially squashed georeferenced raster projections were obtained from maps from both sources.
I understand that every projection distorts lengths. But the distortions I'm seeing are too extreme. Is there a projected CRS that would (roughly) replicate the X-Y dimensions of the original map? My mosaic raster is much larger than 1 Gb, so I show the same issue with an OpenStreetMap raster from the same region as a proxy for my problem (below).
Do I need to use a custom coordinate reference system to obtain a naturally projected georeferenced map image/raster that displays (nearly) equal north-south distances and east-west distances? Or is there an existing CRS that will do this? Is there an existing solution in QGIS that can achieve this?
Here is an example showing an original raster from OpenStreetMap and the georeferenced TIF.
I used the following reference points:
Point Lon Lat (decimal degrees)
1 20.875906 49.856044
2 20.895682 49.843258
3 20.936216 49.844372
4 20.892439 49.87169