reproject dataset

Function Description

Reprojects a single dataset. For vector datasets, the result data after conversion can be saved as a new dataset or the source dataset projection can be directly modified. For raster, image, or model datasets, the result dataset must be saved as a new dataset after projection conversion.

Functional Entry

  • Start tab -> Data Processing group -> Project -> Reproject Dataset.
  • Toolbox -> Data Management -> Projection Settings -> Reproject Dataset.
  • In the workspace manager, select the dataset requiring projection conversion from the context menu -> Properties, then click the Project button under the Coordinate System item in the dataset attribute panel.

Parameter Description

  • Source Dataset: Sets the dataset to be reprojected and its data source. The source coordinate system area displays detailed description information of the source dataset's coordinate system.
  • Conversion Method: Click the drop-down button on the right of the Conversion Method label. The drop-down menu lists over a dozen reference system conversion methods provided by the system, allowing users to select an appropriate one. For details on conversion methods, refer to Reference System Conversion Methods. For applicable scope and methods, see Transformation Model.
Note:

Supports coordinate transformation for planar coordinate system datasets using the four-parameter transformation method. Does not support conversion between planar and geographic coordinate systems.

  • Projection Transformation Parameters: After selecting a conversion method, click the settings button to customize parameters in the parameter settings dialog.

    When choosing a three-parameter method such as Geocentric Translation, Molodensky, or Molodensky Abridged, set three translation parameters (ΔX, ΔY, ΔZ) in the dialog. This transformation is a geocentric shift from one datum center (0,0,0) to another (ΔX, ΔY, ΔZ). The three-parameter shift is a linear translation in meters.

    When choosing a seven-parameter method such as Position Vector, Coordinate Frame, or Bursa-Wolf, set seven parameters: three linear translations (ΔX, ΔY, ΔZ), three rotational angles around axes (Rx, Ry, Rz), and a scale factor (S). Translation parameters are in meters; rotation parameters are in arc-seconds; the scale factor is in parts per million (ppm).

    • Scale Factor: Indicates the scale stretch from the original to the target coordinate system. Required for planar coordinate system conversions; scale factor = unit conversion factor * 1,000,000. For example, converting from planar coordinate system-millimeters to planar coordinate system-meters requires a scale factor of 1,000.
    • Rotation Angle (X/Y/Z): Indicates rotation angle around the X/Y/Z axis in arc-seconds; default is 0.
    • Translation (X/Y/Z): Also called offset, indicates displacement along the X/Y/Z axis in meters; default is 0.
    • Origin Coordinates (X/Y/Z): Indicates the origin coordinates for rotation; default is 0.
    • Import/Export Projection Transformation Parameters File: Click the import button at the bottom of the parameter settings dialog to import a *.ctp file containing saved parameters for the current project. Click the export button to save the current parameters to a specified path for future use.
  • Result Save As: Sets the name and data source for saving the reprojected result dataset.
  • Target Coordinate System: Provides three setup methods as described below. After setting, details display under "Target Coordinate System".
    • Reset Coordinate System: Click the "Reset Coordinate System" button, select "More" from the drop-down menu, and set the target projection in the "Coordinate System Settings" dialog. For details, refer to Projection Settings.
    • Copy Coordinate System: Click the "Copy Coordinate System" button to open the dialog. Choose to copy from a data source or dataset:
      • From Data Source: Select this radio button, click the combo box drop-down button, choose a data source, and set its coordinate system as the target.
      • From Dataset: Select this radio button, click the combo box drop-down button, choose a dataset, and set its coordinate system as the target.
    • Import Coordinate System: Click the "Import Coordinate System..." button, select a projection info file in the "Select" window. Supported formats include Shapefile projection info (*.shp; *.prj), MapInfo Exchange Format (*.mif), MapInfo TAB File (*.tab), image format projection info (*.tif; *.img; *.sit), and projection info files (*.xml).
  • Model Convert Vertex Option: Available only when the source data is a model dataset. Enabled by default for model datasets to prevent misalignment after coordinate transformation.
Note:
  • All projections involve distortion, so transformations between projections are not always fully reversible. Reprojecting data to another projection may not precisely restore the original. Always back up files before reprojecting, and minimize transformation frequency to ensure accuracy.
  • Each projection minimizes distortion for specific regions and properties. Transformations should occur between similar coordinate system scopes to maintain precision. For example, converting a Mercator world map to Gauss-Krüger projection ensures accuracy only near the central meridian, with significant distortion elsewhere.
  • Select a conversion method based on specific conditions. Obtain parameters from authoritative surveying data or validate them using known control points in both coordinate systems.
  • After reprojecting text datasets, text height and angle may change. Adjust these properties post-transformation if needed.
  • The tolerance of the result dataset updates according to the new projection after reprojection.

Related Topics

Batch Reproject

Transform Coordinates

Calculate Transformation Model Parameters