I am trying to calculate the total area covered by c.a. 400 Circles of diameter 15Km. The centers of these circles are stored in a column of type geometry:4326 in my database.
Some circles overlap, and I should not add to the total area the overlapping amount twice.
Until now I tried the follwing approach:1) Use buffer to get circles: select st_buffer(get_location, 15000) from d_station; 2) Use st_union to join the circles into a single multipoint geometry3) use st_area to calculate area.
Unfortunately this approach doesn't work, I think because I am not using st_union in the correct way?
Then I found an interesting tutorial here, which explains something very similar to what I need. Unfortunately I am not able to get a useful result using this approach either.
How can I obtain a list of circles and merged circles polygons, and then calculate the sum of their areas?
أكثر...
Some circles overlap, and I should not add to the total area the overlapping amount twice.
Until now I tried the follwing approach:1) Use buffer to get circles: select st_buffer(get_location, 15000) from d_station; 2) Use st_union to join the circles into a single multipoint geometry3) use st_area to calculate area.
Unfortunately this approach doesn't work, I think because I am not using st_union in the correct way?
Then I found an interesting tutorial here, which explains something very similar to what I need. Unfortunately I am not able to get a useful result using this approach either.
How can I obtain a list of circles and merged circles polygons, and then calculate the sum of their areas?
أكثر...