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I'm trying to combine multiple "strips" of imagery into a single mosaic. Each of these strips is composed of many .tif files, and I have a directory with multiple subdirectories, each which contains one of these strips (big group of .tif files). The .tif files within any one of these strips do not overlap, but the strips themselves do overlap to varying degrees.

According to GeoServer's documentation, I should be able to point the ImageMosaic data store at the root directory to combine several strips. The exact overlap (I think) would be determined by the merge behavior parameter in the layer configuration, as well as the granule sorting parameter. So far, however, every attempt to mosaic all these strips' worth of .tif files together has failed, resulting in a blank image. I'm ultimately wanting to serve this mosaic with a WMTS - and the tiles do get "created" - but they're completely blank. I can request them, and I get an all-white image.

This happens whether I let GeoServer auto-create the shapefile index and properties file, or I make them myself.

I CAN get any of the individual strips' constituent .tif files to mosaic together, and I can serve those images via WMTS. The problem only occurs when trying to merge overlapping bundles of images. If I run the WMTS into ArcMap, zooming way out reveals nothing, while zooming in to certain areas seems to reveal a few actual tiles. I'm guessing there are the areas in which there were no overlapping pixels at all.

My only guess is that without a specific parameter in the shapefile index to reference for granule sorting, GeoServer just decides to serve up nothing in a given area. However, I did make my own ShapeFile index with an arbitrary ranking parameter to test whether I could get the sorting to work and imagery to show up. Still a no go.

Has anyone here had success with mosaicking overlapping imagery? Something major I'm missing?

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  • usually an image mosaic will be all in one directory though I'm not sure if that is a requirement. You may have more luck if you copy all the tiffs into one folder
    – Ian Turton
    Commented Dec 14, 2018 at 10:24

2 Answers 2

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I have been experiencing empty images produced by ImageMosaic layer when I have not written correct CRS definition into .prj file in the layer directory.

When I create ImageMosaic Store in Geoserver, it creates shapefile, .properties and .prj file automatically. It even overrides your .prj file when the .properties file does not exists yet. After creating the ImageMosaic Store you need to override the created .prj file content by WKT definition of CRS of the layer.

When I keep the default CRS in the generated .prj file, the layer produce empty images always when request WMS output in CRS different from CRS used in TFW files.

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This was an image-processing error. Enabling JAI-EXT as outlined at https://docs.geoserver.org/stable/en/user/configuration/image_processing/index.html#jai-ext "fixed" the issue. The entire mosaic of overlapping tiles can show up. However, seeding the tile cache is unusably slow. That's addressed in a separate question: https://gis.stackexchange.com/questions/306310/geowebcache-seeding-for-mosaic-is-unusably-slow

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  • This is the answer which OP added to his question body.
    – Kadir Şahbaz
    Commented Dec 10, 2020 at 12:45

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