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bio website cleverelephant.ca
location Victoria, Canada
age 43
visits member for 3 years, 8 months
seen 41 mins ago

merge keep


1d
revised How to find all features in one table that intersect features in another table in PostGIS?
testing the id will be faster than testing the whole row
Apr
7
awarded  Custodian
Apr
7
reviewed Approve suggested edit on why can't i export geometry data from a shapefile?
Apr
2
answered Split lines at intersections in PostGIS (must be simple but…)
Apr
2
answered Improve speed of PostGIS “nearest neighbor” query?
Mar
30
comment ESRI projection to SRID?
Oh, and once you've figured out the custom offset, you can create your own spatial_ref_sys entry, starting from the EPSG:3452 definition, and then altering the x_0 and y_0 parameters to correct for the custom offset.
Mar
30
comment ESRI projection to SRID?
Yes, in addition to being in stateplane (EPSG:3452), the coordinates have probably been re-scaled in some way. If you can take a single known point in your map, and manually figure out what the lon/lat coordinates are, then project those coordinates INTO EPSG:3452, you can compare the coordinates and see if you can figure out the offset they've taken out of the coordinates.
Mar
28
answered PostGIS Type Modifier Error
Mar
28
comment POSTGIS: function st_collect(geography) does not exist
Indeed, only a small subset of functions are implemented for geography. For all others, just cast, as suggested here.
Mar
27
answered How <-> operator work?
Mar
27
comment How can I GROUP BY linear spatial clusters with PostGIS?
Not smart enough to plop out an answer but the two terms that percolate in my brain are "inter-point distance" and "windowing" (see PostgreSQL manual).
Mar
27
comment ST_NumInteriorRings not returns zero, is a bug?
A multipolygon that answers st_numgeometries == 1 is a simple polygon without disjoint members.
Mar
27
comment ST_NumInteriorRings not returns zero, is a bug?
No, it's not a bug. It's behaviour I'm not entirely happy with, but the alternative could also be considered confusing: if you run ST_NumInteriorRings on a multi-polygon, what should the answer be? # of interior rings in first polygon? sum of interior rings on all?
Mar
27
comment ST_NumInteriorRings not returns zero, is a bug?
You can extract a polygon using ST_GeometryN or you can dump the collection into a result set using ST_Dump
Mar
27
answered ST_NumInteriorRings not returns zero, is a bug?
Mar
24
awarded  Guru
Mar
20
revised Problem with matching a buffer in Openlayers and the same buffer in PostGIS query
added 13 characters in body
Mar
20
comment Problem with matching a buffer in Openlayers and the same buffer in PostGIS query
You cannot cast a 900913 geometry into geography, so if you ran this at the command-line you'd get an error.
Mar
19
answered Problem with matching a buffer in Openlayers and the same buffer in PostGIS query
Mar
14
answered Geometry vs geography for line-to-polygon intersection