Guides · Formats · Coordinate systems
Understand GIS data before you convert it
A conversion can finish successfully and still put a layer in the wrong place. These guides focus on the decisions software cannot safely make for you: identifying an unknown coordinate reference system, checking a UTM zone and knowing what a file format leaves out.
Practical troubleshooting guides
- Coordinate systemsUTM zone 32 or 33? Choosing EPSG:25832 and EPSG:25833Understand the 12°E boundary, why eastings alone are ambiguous and how to test the correct zone.
- CAD and GISDXF has no coordinate system: which one should you choose?Distinguish projected survey coordinates from local drawing coordinates before importing CAD data into GIS.
- ShapefileShapefile without a PRJ file: what to doRead the coordinate ranges, verify a known point and assign the CRS without moving the coordinates.
A safe order of work
- Inspect the source. Confirm the format, layers, geometry types and any coordinate-system metadata before choosing an output.
- Assign before transforming. If a CRS label is missing, identify the CRS that the existing numbers already use. Only then transform them to another CRS.
- Verify a known location. Check at least one feature whose real-world position is known. A plausible-looking extent is not proof.
- Review format losses. Field-name limits, styling, nested folders and unsupported geometry types may not survive every conversion.