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I have been given data from a DigitalGlobe product called Global Basemap. I've been tasked with getting this data into a form usable by our map server, which is running GeoServer 2.4.

The data did not include any form of documentation on the Global Basemap format and I have not been able to find any online. (I found plenty of marketing materials, but no technical specs.) The organization that purchased the data for me does not have any documentation.

The existing raster maps we are hosting on our GeoServer instance take the form of ImagePyramid stores, which I created by running gdal_retile.py on GeoTIFF mosaics. This new, Global Basemap imagery I have been given looks like it's already in some sort of image pyramid format, but not the same format required by GeoServer's ImagePyramid plugin. At the root level of this data there are dozens of directories with names like 8_462_181 and 8_463_173. Inside each one of those directories we have directories and files like so:

drwxr-xr-x  10
drwxr-xr-x  11
drwxr-xr-x  12
drwxr-xr-x  13
drwxr-xr-x  14
drwxr-xr-x  15
drwxr-xr-x  16
drwxr-xr-x  17
drwxr-xr-x  9
-rw-r--r--  cacheViewer.html
-rw-r--r--  root.kml
drwxr-xr-x  var

Directories 9 through 17 contain subdirectories. 10 has more subdirectories than 9, 11 has more than 10, etc. and that is what makes me think that this structure represents an image pyramid. Each of those subdirectories contains JPEG files with matching KML, .proj, and world (.jgw) files. For example:

44542.jgw
44542.jpg
44542.kml
44542.prj
44543.jgw
44543.jpg
44543.kml
44543.prj
44544.jgw
44544.jpg
44544.kml
44544.prj

The structure required by GeoServer's ImagePyramid plugin is that the lowest level image tile files go into a directory name 1, the next level up, i.e., fewer tiles, go into a directory named 2, etc.

Question 1: Do I merely need to rename the existing directories 9 through 17 as 8 through 1.

Question 2: There is no over-arching image, world file, or mosaic that covers the entire region. Will I have to use gdal_merge or something similar to create one?

  • does gdalinfo give you anything helpful when run against the base file? – Ian Turton Dec 22 '14 at 15:41
  • If I run gdalinfo on any one of the JPG files (and there are millions of them), then I get info for that one tile, e.g., size, origin coordinates. But there is no single "base file," just lots and lots of little mosaics spread over a very large number of directories. And gdalinfo doesn't do anything with a directory name, i.e., it just tells me "ERROR 4: `8_462_181' not recognised as a supported file format." – dgvid Dec 22 '14 at 15:54

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