filters.reprojection

The reprojection filter converts the X, Y and/or Z dimensions to a new spatial reference system. The old coordinates are replaced by the new ones. If you want to preserve the old coordinates for future processing, use a filters.ferry to create copies of the original dimensions before reprojecting.

Note

When coordinates are reprojected, it may significantly change the precision necessary to represent the values in some output formats. Make sure that you’re familiar with any scaling necessary for your output format based on the projection you’ve used.

Default Embedded Stage

This stage is enabled by default

Streamable Stage

This stage supports streaming operations

Example 1

This pipeline reprojects terrain points with Z-values between 0 and 100 by first applying a range filter and then specifying both the input and output spatial reference as EPSG-codes. The X and Y dimensions are scaled to allow enough precision in the output coordinates.

[
    {
        "filename":"input.las",
        "type":"readers.las",
        "spatialreference":"EPSG:26916"
    },
    {
        "type":"filters.range",
        "limits":"Z[0:100],Classification[2:2]"
    },
    {
        "type":"filters.reprojection",
        "in_srs":"EPSG:26916",
        "out_srs":"EPSG:4326"
    },
    {
        "type":"writers.las",
        "scale_x":"0.0000001",
        "scale_y":"0.0000001",
        "scale_z":"0.01",
        "offset_x":"auto",
        "offset_y":"auto",
        "offset_z":"auto",
        "filename":"example-geog.las"
    }
]

Example 2

In some cases it is not possible to use a EPSG-code as a spatial reference. Instead Proj.4 parameters can be used to define a spatial reference. In this example the vertical component of points in a laz file is converted from geometric (ellipsoidal) heights to orthometric heights by using the geoidgrids parameter from Proj.4. Here we change the vertical datum from the GRS80 ellipsoid to DVR90, the vertical datum in Denmark. In the writing stage of the pipeline the spatial reference of the file is set to EPSG:7416. The last step is needed since PDAL will otherwise reference the vertical datum as “Unnamed Vertical Datum” in the spatial reference VLR.

[
    "./1km_6135_632.laz",
    {
        "type":"filters.reprojection",
        "in_srs":"EPSG:25832",
        "out_srs":"+init=epsg:25832 +geoidgrids=C:/data/geoids/dvr90.gtx"
    },
    {
        "type":"writers.las",
        "a_srs":"EPSG:7416",
        "filename":"1km_6135_632_DVR90.laz"
    }
]

Options

in_srs: Spatial reference system of the input data. Express as an EPSG string (eg “EPSG:4326” for WGS84 geographic), Proj.4 string or a well-known text string. [Required if not part of the input data set]
out_srs: Spatial reference system of the output data. Express as an EPSG string (eg “EPSG:4326” for WGS84 geographic), Proj.4 string or a well-known text string. [Required]
in_axis_ordering: An array of numbers that override the axis order for the in_srs (or if not specified, the inferred SRS from the previous Stage). “2, 1” for example would swap X and Y, which may be commonly needed for something like “EPSG:4326”.
in_coord_epoch: Coordinate epoch for the input coordinate system as a double. [Default: 0]
out_axis_ordering: An array of numbers that override the axis order for the out_srs. “2, 1” for example would swap X and Y, which may be commonly needed for something like “EPSG:4326”.
out_coord_epoch: Coordinate epoch for the output coordinate system as a double. [Default: 0]
error_on_failure: If true and reprojection of any point fails, throw an exception that terminates PDAL . [Default: false]