Reproject

Draft: written, not yet checked by a person Operation · reproject

Transforms vector features from their coordinate reference system into another.

Pitfall. A datum change (NAD27 to NAD83, or between NAD83 realizations) needs the right transformation, or positions shift by metres.

Pitfall. Data with no CRS cannot be reprojected correctly; assigning a CRS is a different step from reprojecting.

About this operation
Also called	Project, Reproject layer, transform, change coordinate system
Group	`vector/crs`
Checks	`crs.present, crs.area_of_use, crs.reprojected`
Pitfalls	2 listed above
Columbus tool	`vector_op · reproject`
Notes	Not stated
Status	active
Broader	Not stated
Narrower	Not stated
Related	`reproject-raster`

Parameters

Name	Type	Required	Default	Values	Note
`crs`	crs	yes	Not stated	Not stated	Target CRS, e.g. EPSG:3081.

Direction	Name	Type	Geometry	Note
Input	`layer`	vector	Not stated	Not stated
Output	`output`	vector	Not stated	Not stated

Engine	Tool	Parameters	Differences
`apache-sedona`	`sedona.sql.ST_Transform`	`crs` → `target_crs` `layer` → `geometry`	source_crs can be given explicitly; otherwise the geometry's SRID is used. A Spark SQL function: arguments are columns or column names, run over a Spark DataFrame.
`gdal`	`gdal vector reproject`	`crs` → `output-crs` `layer` → `input` `output` → `output`	None noted
`geopandas`	`geopandas.GeoSeries.to_crs`	`crs` → `crs`	Called on the GeoSeries (or GeoDataFrame) itself; fails if the data has no CRS set.
`postgis`	`st_transform`	`crs` → `#2` : An SRID (4326), or to_proj for a PROJ string; the SRID must be in spatial_ref_sys. `layer` → `#1`	Uses the database's spatial_ref_sys and PROJ; results can differ from GDAL where the transformation chosen differs.
`qgis`	`native:reprojectlayer`	`crs` → `TARGET_CRS` `layer` → `INPUT` `output` → `OUTPUT`	OPERATION can force one coordinate operation (a specific datum transformation) instead of the one PROJ picks.
`rasterio`	`rasterio.warp.transform_geom`	`crs` → `dst_crs` `layer` → `geom`	Takes GeoJSON-like geometries and needs the source CRS (src_crs); attributes are not carried.
`sf`	`sf::st_transform`	`crs` → `crs` `layer` → `x`	None noted
`terra`	`terra::project`	`crs` → `y` `layer` → `x`	The same function reprojects SpatRasters (raster reproject).