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I have a data source with a folder pyramid that contains several thousands of GeoTIFF files, about 70Mb each. I would like to process these so that I can display the map overlays on a OpenLayers web map.

Since the maps have a frame around them its probably not possible to have them into a single covering layer so my approach would be to display them as single maps that would be displayed depending on where on the map the user is.

How and with what software would be the best way to process all these files so that they can be displayed by OpenLayers? enter image description here

  • some of these questions may help - gis.stackexchange.com/search?q=%5Bgdal%5D+collar – Ian Turton Jan 25 at 12:17
  • If your geotiffs are in a standard format you might be able to use a script to remove their collars, and then seemlessly mosaic them. See edc.uri.edu/blog/… for a global mapper based solution. I recall removing collars from USFS topo tifs by using the index file to clip raster so if your maps conform to an available vector tile file you could go that route in ArcGIS or QGIS. – johns Jan 25 at 14:36
  • Yes, I have to look that up. If all the images is in the same format a clipping could be done. That would be nice. But I know these map are created under a period of 20-25 years so my guess is that they are not exactly the same. – Mårten Swärd Jan 25 at 14:47
  • I have looked att Geoserver ImageMosaic but I dont know if this can read in to several levels of subfolders and if it can handel such amount of data in both quantity and size – Mårten Swärd Jan 25 at 14:49
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I have been looking a bit for a solution. And I am thinking of this approach:

1. create a python script that traverse the folder structure and processes each image. I think that the geotiff has four gcp:s, each in every corner of the map. By these it would be possible to cut the raster image to get rid of the frame with gdal_translate and in the process compress the files.

Then reproject with gdalwarp to a current standard projection and store all result files in one folder.

2. Let geoserver serve this folder with geotiff files as one layer so that I can display it in my Openlayers application.

That is my best guess so far.. I'm not sure if Geoserver ImageMosaic could handle several thousands of geotiff? What do you guys/girls think? Is this solution something that could work? The part that I have most doubts about is the Geoserver-part, my experience with Geoserver (and Java) is not something that give me high hopes when it comes to large amount of data.

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