Global Mapper v25.0

merge Geotiff's

Aerialmapper
Aerialmapper Global Mapper User
edited October 2013 in Technical Support
I have 2 Geotiff images (with .tfw files) created from other software. 1.74 GB and 1.66 GB. with a seamless match line joining the two images. When I try to 'export' raster data I am informed of the Big Tiff option.

1) What is a big tiff as opposed to a regular tiff?

2) No .tfw file is created.

3) Size of new file is only 1.1 GB


I am new to GB and could find no information on help files or in forums.


Any help would be appreciated.

Comments

  • global_mapper
    global_mapper Administrator
    edited October 2013
    A BigTiff is an extension to the base TIFF format to support images that might be over 2GB in size (yours didn't end up that large after compression, but that's hard to know prior to export). Not all applications can handle BigTiff files, but most modern ones can.

    When exporting from GM there is a checkbox to specify whether to create a World File (TFW) or not. Make sure that is checked.

    What compression option did you use? You could easily get a smaller result for the same data at the same resolution if you used better compression (lossy like JPEG-in-TIFF) or loss-less like Deflate or LZW.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation