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Mosaics with Multiple Projection Systems

GeoExpress can create raster mosaics out of images with multiple projection systems. However, because images with different projection systems display discrepancies in their positioning, GeoExpress reprojects all of the images to the same coordinate reference system (CRS). By default, GeoExpress reprojects images to the WGS 84 projection system. To use a different projection system, see Reprojecting an Image.

To add images with multiple projection systems to a mosaic, select the Allow multiple projection systems option when you create the mosaic. To select this option after you create a mosaic, complete the following steps:

1. Select a mosaic in the Job List.

2. Click Advanced in the Properties tab.

   The Advanced Job Options dialog box appears.

3. In the Output tab, select Allow multiple projection systems.

NOTE: When you select Allow multiple projection systems, GeoExpress also selects the Enable multiresolution mosaicking option. Because reprojecting an image changes the geographic area covered by the image, reprojection often changes the resolution of an image. As a result, GeoExpress automatically selects the Enable multiresolution mosaicking option to correct discrepancies in image resolution.

If one or more of the tiles in the mosaic does not have a valid CRS, or if you are using world files, you can manually assign a CRS to each tile in the Tile Manager. For more information, see Assigning a CRS to Tiles.