/bounds of objects that cross the Antimeridian

[jonaraphael]

Typically objects are compact single polygons that return reasonable values [minx, miny, maxx, maxy] when you get their bounding box.

Case of interest:

When an object crosses the antimeridian (i.e. ±180º longitude), the typical behavior is splitting it into a multipolygon with disconnected elements on opposite sides of the map.

Current behavior:

The current implementation of the /bounds endpoint does not treat this correctly... It returns a degenerate bbox that looks like [-180, miny, 180, maxy], spanning the whole globe

Preferred behavior:

Instead, according to the GeoJSON spec: https://datatracker.ietf.org/doc/html/rfc7946#section-5.2 , the bbox should have the "wrong" order for the longitude coordinates (i.e. minx > maxx). Note that it is not simply enough to return[180, miny, -180, maxy]. The endpoint should actually find the leftmost bound of the rightmost polygon as minx, and the rightmost point of the leftmost polygon as maxx.

A frontend application may then choose to handle this case as best they see fit, for instance see: https://github.com/developmentseed/rio-viz/blob/main/rio_viz/templates/index.html#L1202-L1210

Open question:

I'm not sure how this behavior should be defined in more complex situations, where the object is not convex. For instance, a U-shaped polygon that crosses the antimeridian could result in multipolygon with 3 components.

Example:

/bounds?sceneid=S1A_IW_GRDH_1SDV_20230726T183302_20230726T183327_049598_05F6CA_31E7 returns [-180.0, 61.06949078480844, 180.0, 62.88226850489882] because it's productInfo.json looks similar to this:

"footprint" : {
    "type" : "MultiPolygon",
    "coordinates" : [ 
        [ [ [ 180.0, 62.52138872791733 ], [ 179.94979152463551, 62.52658106629492 ], [ 179.46990657679865, 62.57485506167223 ], ..., [ 179.97829453382462, 61.06949078480844 ], [ 180.0, 61.115074335603865 ], [ 180.0, 62.52138872791733 ] ] ], 
        [ [ [ -180.0, 62.52138872791733 ], [ -180.0, 61.115074335603865 ], [ -179.95528668344312, 61.208976568342585 ], ..., [ -179.34123633603335, 62.451941133348306 ], [ -179.81084543337622, 62.50182719954094 ], [ -180.0, 62.52138872791733 ] ] ] ]
  },