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I have a set of satellite image tiles from Bing Maps (info here). The tiles' names specify tile coordinates within the tile system and zoom, e.g. 156608-142775-18.jpg.

An example set of tiles:

['156608-142775-18.jpg', '156608-142776-18.jpg', '156607-142777-18.jpg', '156608-142772-18.jpg', '156607-142776-18.jpg', '156608-142777-18.jpg']

Here are the tiles visualized:

Visualized tiles

What I need to do is to merge all neighboring images into one image. So, in my example, I wish to merge the lower five tiles into one and output two images - the big merged image and the upper single tile which has no neighbors.

I am not sure how to achieve this. It seems to me there should be a simple solution to this that I cannot figure out.

I will use the same code for merging a large number of tiles so I want to avoid solutions that use a lot of memory or take long time. I work in Python. I don't need the actual code, just an idea how to do this.

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  • Which python GIS libraries are you using? – BERA Jul 16 '20 at 19:30
  • geopandas, shapely, geojson, but i am free to use others, too – Jan Pisl Jul 16 '20 at 19:58
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    Then a similar workflow as my answer should work. Just list files instead of raster layers. – BERA Jul 16 '20 at 20:01
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    Yes, I think I get the idea. Thanks a lot! – Jan Pisl Jul 16 '20 at 20:17
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This could give you some ideas, I use QGIS and networkx python module to check if raster extents intersects:

import networkx as nx

layerlist = [layer for layer in QgsProject.instance().mapLayers().values()]

rasterlist = []
for l in layerlist:
    for l2 in layerlist:
        if l.name()!=l2.name() and l.extent().intersects(l2.extent()):
            if l.extent().intersect(l2.extent()).perimeter()>0: #Excludes rasters connected only in corners
                rasterlist.append([l.source(), l2.source()])

G=nx.Graph()
G.add_edges_from(rasterlist)
adjacent_rasters  = list(nx.connected_components(G))

print('\n')
single_rasters = [r.source() for r in layerlist if not any(r.source() in i for i in rasterlist)]

print('single_rasters: ',single_rasters)
print('\n')
for e, rastergroup in enumerate(adjacent_rasters,1):
    print('Group {} has {} rasters: {}'.format(e,len(rastergroup),rastergroup))
   

enter image description here

Then merge them.

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