Projection of External Data


Use the following menu commands to project data files:
  • File – Project Shape File: Project data in ESRI Shape files.
  • File – Project Image: Project a variety of raster image files. PNG is the recommended format. TIFF is currently slow to read.
  • File – Project Grid: Project ESRI ASCII Grid files containing digital elevation models or other raster data.
This will project files using the current projection of the frontmost window. To apply a projection stored in a file, first open the file (File–Open) and then select File–Project Shape File, Project Image or Project Grid.

Important: All data must be in the “geographic” projection (i.e. longitude / latitude or Plate Carrée projection).

Reprojected raster images are saved in TIFF format. Reprojected grids, such as elevation data, are saved in ESRI ASCII Grid format.

Raster data with a width-to-height ratio of 2:1 is automatically georferenced, assuming a Plate Carrée projection.

When reprojecting raster images or grid data, users have the choice between Nearest Neighbor or Bi-cubic Interpolation in the Preferences dialog. Use Nearest Neighbor for categorical data, such as thematic land cover data that should not be interpolated. Use Bi-cubic Interpolation for continuous tone images or continuous grid data, such elevation models.