(You probably know this but) quadtrees are indeed used extensively for both of those things. Whole buncha programs can use them (though there are other good op

(You probably know this but) quadtrees are indeed used extensively for both of those things. Whole buncha programs can use them (though there are other good options as well) for geospatial: https://www.elastic.co/guide/en/elasticsearch/reference/current/geo-shape.html https://www.elastic.co/guide/en/elasticsearch/reference/curr...