Timeline for Merge buffers PostGIS
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 7, 2018 at 16:49 | comment | added | zakaria mouqcit | In this case p should be clustered in an other group one grouo shoud contain only those which are separated to each other by 10m | |
| Mar 7, 2018 at 15:56 | history | edited | geozelot | CC BY-SA 3.0 | added suggestion from comment |
| Mar 7, 2018 at 15:22 | comment | added | geozelot | @dbaston ah, damn, yes I keep forgetting that...I will change my queries ,) thanks! didn´t you even implement ST_ClusterDBSCAN? that´s some aggressive promoting... | |
| Mar 7, 2018 at 15:18 | comment | added | dbaston | Definitely use ST_ClusterDBSCAN if you want to assign IDs back to the original points; see gis.stackexchange.com/a/273613/18189 | |
| Mar 7, 2018 at 15:18 | comment | added | geozelot | @zakariamouqcit to your 10m limit: imagine a couple of points in a straight line, each at a distance of 9m to each other ( p1 <- 9m -> p2 <- 9m -> p3); which one do you want to have within a cluster? p1 is 18m from p3, yet each has a distance of less than 10m to p2. I fear that you need another attribute or another restriction to focus your clusters the way you want them | |
| Mar 7, 2018 at 15:07 | comment | added | geozelot | @zakariamouqcit hm...it´s not like ST_ClusterWithin would simply miss some points due to having a bad day, I just ran all queries on a table with proper UTM projection and got 100% correct results. are your points projected properly? | |
| Mar 7, 2018 at 14:55 | comment | added | zakaria mouqcit | Also, inside the cluster, the distance between all points should be 10m. because this methode groups adjacent points with 10 but I can have in the same cluster two points which are in 20. All points inside the polygone must be within 10 m | |
| Mar 7, 2018 at 14:52 | comment | added | zakaria mouqcit | Seems that it takes only the points within 10 m but not those which may be in 2,5 or 8 for instance. | |
| Mar 7, 2018 at 14:42 | comment | added | geozelot | @Vince Of course, thanks, but I was just adding to the inital query, so the second one is a mere mockup to exclude non-polygons. I´ll add a better one ASAP (since then the whole ordinal extraction is only overhead)... | |
| Mar 7, 2018 at 14:34 | comment | added | Vince | You can use row_number () over ())::integer to populate a sequential id col | |
| Mar 7, 2018 at 14:32 | comment | added | zakaria mouqcit | @ThingumaBob I tried your method, and seems similiar to point aggregation in ArcGIS. This doesn't cluster all points. I have some points which are in a distance of 2, 7 meters are not clustered. I want all points which are separated by 10 m max be grouped on a polygon. | |
| Mar 7, 2018 at 14:23 | comment | added | John Powell | unnest(clst.arr) with ordinality, sweet. I have absolutely no idea if this answers the question or not, but it is a fabulous answer to some question :-) | |
| Mar 7, 2018 at 14:16 | history | edited | geozelot | CC BY-SA 3.0 | deleted 2 characters in body |
| Mar 7, 2018 at 13:29 | history | answered | geozelot | CC BY-SA 3.0 |