6,764 reputation
244133
bio website djq.me
location Dublin, Ireland
age
visits member for 3 years, 10 months
seen Jul 21 at 21:59

interested in postgis, geodjango, qgis, python, R and LaTeX.

twitter: @djq


Dec
12
comment How to re-project shapefiles?
I don't know your dataset or the google values well enough to judge, but as a reference a point in Dublin, Ireland using EPSG:900913 is -788694.0, 6956099.0. These coordinates are not lat/lng they are x/y in meters.
Dec
12
comment How to re-project shapefiles?
Can you try something like EPSG:900913 as a test? Moving between lat/long projection systems is still re-projecting; WGS84 is a lat/long system.
Dec
12
comment How to re-project shapefiles?
What do you want to project it to? You chose EPSG:4326 which converted the shapefile from the previous projection to WGS_84
Dec
12
comment How to re-project shapefiles?
yes... you can't reproject a qgis project file which is why I gave my first answer. Then I realized you wanted to reproject the shapefiles in bulk. One way of doing this is to loop through all the files in a folder using the command line with ogr (another would be to see if you can pass ogr a folder of shapefiles).
Dec
12
comment How to re-project shapefiles?
Are all the shapefiles in the one folder?
Dec
12
comment How to re-project shapefiles?
Are you trying to reproject a shapefile? A project file has a .qqs ending, a shapefile ends with .shp. I don't think you can re-project a project file but I could be wrong.
Dec
12
comment How to handle postgresql/postgis geometry type errors in a function?
Thanks for the suggestion. I still get an aggregation error though when using this approach: ERROR: aggregates not allowed in WHERE clause LINE 7: AND GeometryType(ST_ConcaveHull(ST_Collect(geom), 0.85)) != 'LINESTRING'
Dec
12
comment postgis error: when adding features geometry has z dimension but column does not
Thanks - I was unaware of it. Happy to add it to my answer unless you'd prefer to answer yourself......
Dec
11
comment Projecting PostGIS in Openlayers
Can you explain a little more what you want to do? To move between different projections you can use ST_Transform(). Many web-mapping tools use web-mercator - for example the google SRID for web-mapping is 900913.
Dec
11
comment How to speed up queries for raster databases?
I agree - perhaps I did not emphasize that it is only useful if several values are needed at the same time; I'll clarify this.
Dec
11
comment How fill length and feature count in PostGIS table for each polygons
If you can, it's better not to use capitalized column names. Then you can write m.townname instead of m."TownName". In PgAdmin for example, sometimes the capitalized letters are not shown which can be puzzling.
Dec
10
comment building opentripplaner gtfs.zip
Please use the edit link on your question to add additional information. The Post Answer button should be used only for complete answers to the question.
Dec
5
comment Can't drop table with geography column
Can you login into the database using psql?
Nov
26
comment Geographic locators within Polygons
It sounds like a term you should search for is spatial join
Nov
23
comment Do postgres 9.1, postgis 2.0 from stackbuilder and pgrouting 1.0.3. work together?
Your accept rate for previous questions is 0. Did any answers to your previous questions solve your problem? If so, please consider marking the questions as answered by ticking the checkmark beside the answer.
Nov
23
comment Do postgres 9.1, postgis 2.0 from stackbuilder and pgrouting 1.0.3. work together?
I've also had success using pgRouting 1.0.5 on PostGIS 2.0/postgres 9.1
Nov
23
comment Which GIS (with GUI) produces good-looking maps for a reasonable price?
Add a comment about mapshaper.com/test/MapShaper.swf in my answer. You can reduce your data hugely with a polygon simplification approach.
Nov
21
comment Removing small spaces (slivers) between polygons?
If you paste a link to the images you are referring to I can add them in.
Nov
21
comment Is it possible to export raster data from PostGIS or MapServer as a base64 string?
Yes! That worked. I used SELECT encode(ST_AsPNG(ST_AsRaster(ST_Buffer(ST_Point(1,5),10),150, 150, '2BUI')), 'base64') and was able to load that into my browser.
Nov
15
comment How to create Vector Polygons at the same amazing speeds GISCloud is able to render them?
@RagiYaserBurhum There is a nice explanation of how this was used for travel isochrone mapping using a similar technique: mysociety.org/2012/11/08/…