Dataset Projection Transformation

Function Description

Perform Projection Transformation for a single Dataset. The Result Data after Vector Dataset transformation can be saved as a Dataset, or the Source Dataset projection can be directly transformed; Result Dataset needs to be saved as New Dataset after raster, image or Model Dataest conversion projection.

Function entrance

  • Start tab-> Data Processing group-> Projection Transformation-> Dataset Projection Transformation.
  • Toolbox-> Data Management-> Projection Settings-> Dataset Projection Transformation.
  • In Workspace Manager, select the Context Menu-> Properties of the Dataset whose projection needs to be transformed, and select the Coordinate System item-> Projection Transformation button in the Dataset attribute panel.

Parameter Description

  • Source Data: Set the Dataset for Projection Transformation and its Datasource. The Source Coordinate System area displays the Detail Description information for the Source Dataset coordinate system.
  • Conversion Method: Click the Drop-down Button on the right side of the Conversion Method tab. The drop-down menu list that pops up displays more than ten reference system conversion methods provided by the system. The user can select an appropriate reference system conversion method. For a description of the conversion method, refer to the Description of reference frame conversion method . Refer to Transformation model for transformation methods and Scope of application .
Caution:
Coordinate Transformation of Planar Coordinate SystemDataset is

supported, and the Four-parameter Transformation method is provided. Conversion between Planar Coordinate System and Geographic Coordinate System is not supported.

  • Projection Transformation Parameters: Select different conversion methods and click the Settings button. Different parameters can be customized in the Parameter Settings dialog box.
    • When a three-parameter conversion method, such as Geocentric Transalation, Molodensky, or Molodensky Abridged, is selected, you need to set three translation parameters in the Parameter Settings dialog box. (ΔX, ΔY, ΔZ). This transformation is essentially a geocentric transformation from the center of one datum (0,0,0) to the center of another datum (ΔX, ΔY, ΔZ). A three-parameter transformation is a linear translation in meters.
    • When the seven-parameter conversion method is selected, such as Position Vector, Coordinate Frame, or Bursa-wolf, in the Parameter Settings dialog box, you need to set seven parameters, that is, three linear translation parameters (ΔX, ΔY, .DELTA.Z), three angular parameters of rotation about the axis (Rx, Ry, Rz), and a scale difference (S). The translation parameter is in meters; the rotation parameter is in angular seconds; and the scale difference is in parts per million (ppm).
    • Import/Export Projection Transformation Parameter File: Click the import button below the Parameter Settings dialog box. You can import a Projection Transformation Parameter File with a suffix of *.ctp to import the parameter information saved in the Projection Transformation Parameter File. Parameter Settings as the current Projection Transformation; Click the Export button below the Parameter Settings dialog box to export the parameters currently set in the Parameter Settings dialog box to the specified path, and then import them when needed.
  • Result Save As: Set the save name of the Result Dataset after the Projection Transformation and the Datasource where it is saved.
  • Target Coordinate System: Three setting methods are provided, and the specific operations are as follows. After setting the target projection, the Details of the target projection will be displayed in the Target Coordinate System ".
    • Reset coordinate system: Click "Reset coordinate system" button and select "More" in the drop-down menu to set the target projection in the "Coordinate System Settings" dialog box. Please refer to Projection Settings for the specific operation of Coordinate System Settings.
    • Copy Coordinate System: Click the "Copy Coordinate System" button to pop up the "Copy Coordinate System" dialog box. You can choose to Copy from Datasource or Copy Dataset:
      • From Datasource: Select the From Datasource radio box, click the Drop-down Button in the combo box, and select a Datasource. Set the Coordinate System Settings of the Data source as Target Coordinate System.
      • From Dataset: Select the From Dataset radio box, click the Drop-down Button in the combo box, and select a Dataset. Set the Dataset's Coordinate System Settings to Target Coordinate System.
    • Import Coordinate System: Click the "Import Coordinate System.." "Button. In the pop-up" Selection "window, select the Projection Info File and import it. Support importing Shapefile Projection Info File (*.shp; *.prj), MapInfo Exchange Format (*.mif), MapInfo TAB File (*.tab), image format Projection Info File (*.tif; *.img; *.sit）、Projection Info File（*.xml）。
  • Model Convert Vertex option: The Model Convert Vertex option is available only when the source data is a Model Dataest. For Model Dataest, Model Convert Vertex is checked by default to prevent misalignment of objects after Coordinate Transformation.
Caution:
    Projection Transformation exists in
  • any projection, so the transformation process between different projections is usually not completely reversible, that is, map data can be transformed from its original Projection Transformation to some other projections, but it can not always be transformed back very accurately. Therefore, the user should back up the original file before performing the Projection Transformation. Moreover, the number of projection transformation should be reduced as far as possible in order to make the result of projection transformation more accurate.
  • Each projection is designed to reduce the deformation of a given area on a given characteristic, so each projection has a certain Scope of application. When carrying out projection transformation, the transformation should be carried out between the ranges of similar coordinate systems as far as possible, otherwise the accuracy of the projection transformation results is difficult to guarantee. If a World Map of Mercator projection is converted to Gaussian projection, the result can only be guaranteed to be accurate in the vicinity of Center Meridian, which will lead to huge deformation in the area far from Center Meridian.
  • In practical work, which conversion method is used depends on the specific situation. For the determination of each parameter, please purchase authoritative measurement data, or verify the correctness of the parameters through the coordinates of the known control points in the two Coordinate Systems.
    • After
  • a Text Projection Transformation, the text height and angle are transformed accordingly. If the user does not need such a change, he needs to reset the height and angle of the converted Text.

Related topics

Batch Projection Transformation

Coordinate Point Conversion

Model Transformation Parameter Calculation