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location Wellington, New Zealand
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visits member for 3 years, 9 months
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I'm a hydrogeologist. An expert of many random things.


2d
comment Insert values in Postgresql in Java
If lat is latitude and log is longitude, you have to swap them, since the correct axis order for PostGIS is POINT(log lat)
2d
comment Computing intersections for each geometry in a table
yes, it will be half the number of rows, since each intersection pair won't be double counted. With a.id < b.id, there will have label 1 intersects with 2, but with a.id != b.id, there will be an additional label 2 intersects with 1. Try it!
Nov
20
answered Insert values in Postgresql in Java
Nov
19
comment Computing intersections for each geometry in a table
Great question. a.id < b.id will make sure there is one match between the pair, otherwise you will see double counts for (symbolically) A.intersects(B) and B.intersects(A). Try it on a smaller subset to see.
Nov
18
revised Computing intersections for each geometry in a table
tags, fix title
Nov
18
answered Computing intersections for each geometry in a table
Nov
17
answered OGR2OGR and SQL: selecting 30 biggest places from a country?
Nov
17
comment OGR2OGR and SQL: selecting 30 biggest places from a country?
This is a great workaround for versions before GDAL/OGR 1.10
Nov
13
answered Piping data to ogr2ogr
Nov
13
answered Error while make Build osm2pgrouting on openSUSE 13.2
Nov
13
answered How to create a raster tiff (dem / heightmap) from a mesh of xyz points?
Nov
12
comment invalid KML representation on ST_GeomFromKML
I cannot reproduce this error with PostGIS 1.5 to 2.1. Do you have the required libxml2 2.6+ library?
Nov
12
comment How to rename field names in a shapefile from the commandline?
You can also list the field names using ogrinfo -so inputfile.shp inputfile
Nov
11
comment Fiona write crashes
On what line does the script crash? I can't reproduce this with Python x64 on Windows with same version of fiona from here.
Nov
10
comment 1km circles around lat-long-points in many places in world
@mkennedy you have a good point. projected is indeed always at (0, 0), and buffered has the points ±1000 m in x- and y-directions. If it were critical to optimise this, then just transform a simple Cartesian version of the buffer from the dynamic AEQD to WGS84.
Nov
10
comment 1km circles around lat-long-points in many places in world
Great feedback, an AEQ projection is obviously performing much better for this technique, so I've switched out gnomic. AEQP will also hold up for much greater distances, like in the 10,000+ km range.
Nov
10
revised 1km circles around lat-long-points in many places in world
Yes. azimuthal equidistant projection is much better
Nov
10
comment 1km circles around lat-long-points in many places in world
That's the same approach described in the question, along with the limitations of this technique.
Nov
10
answered 1km circles around lat-long-points in many places in world
Nov
10
awarded  Disciplined