Showing images of large area in website with thousands of large aerial images hosted on remote server

Question

To be able to use TMS service using GDAL2TIle, one has to make a mosaic of all of images first which is impractical given the fact that there are thousands of aerial images, each 3500x3500px large.

Is there any other solution to use TMS or WMS services without creating a mosaic of the whole aerial images first?

If not, then how it that even possible that we have a layer in OSM-iD for the NRW or Bavaria in Germany consisting of a large number of aerial images or even the whole world in the aerial Bing layer. It is unbelievable that all those images were merged to create a mosaic and then tiled to be able to use either TMS or WMS service.

Answer 1

With big data sets the image mosaics are usually virtual. There is some data structure that is like a table of contents or image index that tell where to find the original images.

GeoServer users create a virtual mosaic with https://docs.geoserver.org/latest/en/user/data/raster/imagemosaic/index.html, MapServer users do the same with tileindex https://mapserver.org/optimization/tileindex.html. GDAL users use gdalbuildvrt https://gdal.org/programs/gdalbuildvrt.html.

The formats of image indexes vary. GDAL VRT is using XML, MapServer and GeoServer are using shapefile or some other supported GIS vector format.