Vector Intersection Process

[ThorodanBrom]

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[ThorodanBrom]

• To get intersection of collections with a boundary, may have to use both ST_Within and ST_Contains or use one and switch around parameters
• Question - do we get all features of all chosen collections?
  • This is performance-intensive because lot of GeoJSON data will be sent back
  • UI has to be able to organize the collections into different layers
• Option 1
  • Have an API/process that works very similar to the /items API, only difference is that it does filtering by ST_Within instead of ST_Intersects nowt
  • Use the normal pagination to get all features + have button to Get More...
  • One collection at a time
• Option 2
  • Get the list of collections properly
  • Then use the normal /items API to get all features + Vector Clipping in OpenLayers - https://openlayers.org/en/latest/examples/layer-clipping-vector.html
• Option 3
  • Implement filter-crs in the /items API - which is part of the Features Filter extension and don't specify that we are conforming to filter
• Option 4
  • UI has to be able to find the correct Z,X,Y tile that fully encompasses the boundary
  • If they find that, they can call a process that can potentially generate an MVT tile using ST_AsMVT that can have all collections as different layers as well in that single tile
  • We can supply only those geometries that we want to have for that tile so no features outside the boundary will be present
  • We can also try to calculate the tile in which a bbox surrounding the boundary can fully fit - https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames - the slippy tiles spec specifies how to find a tile given a point and zoom level.