3
votes
2answers
53 views

Is transformation of spatial data lossy?

I have a shapefile that contains data of a country from the following Geographic Coordinate System ( GCS_North_American_1927 aka NAD27 ) contents from the shape file .prj: ...
1
vote
1answer
48 views

QGIS with CH1903/LV03 and WGS84 layers

I have a few CH1903/LV03 layers (lake, river and the country border of Switzerland) and a layer in WGS84 (two points of two cities, Vaduz and Bregenz). On-the-fly-transformation is activated but ...
2
votes
0answers
46 views

Using ST_Affine() and trans_param() functions on vector layer

After reading this post How to georeference a vector layer with control points? I decided to give it a try to move/rotation/scale a polygon using Postgis. I have two polygons, polygon_from and ...
0
votes
2answers
92 views

Convert the_geom to text and then transform

I have this query that returns the_geom as text. However how could I also apply a transform to the same query. I can do this separately with the second example. Though I would like to do this to all ...
2
votes
1answer
1k views

Transforming from SRID 900913 to 4326 with PostGis

I have two Postgres tables with different SRIDs, 4326, and 900913. I want to convert the latter to 4236. I first changed the SRID using: Select UpdateGeometrySRID('table', 'geomcolumn', 4326). I ...
0
votes
0answers
72 views

Transforming WFS Projection

I am trying to overlay features from a WFS using OpenLayers, my geometries in database are in EPSG:27700 and my map's projection is EPSG:3857. My mapfile returns data in EPSG:27700. Is there any way ...
3
votes
1answer
247 views

When trying to convert lon/lat (curved) coordinates to projected (flat) coordinates with ruby, the second (y axis) projected coords are inaccurate

So I have created a polygon using Google Earth pro. I've exported it into a kml file, which I can then parse using ruby's XML/HTTP-parsing Nokogiri gem into an array of WKT points (LinearRing) thats ...
4
votes
3answers
347 views

generate spatial geom from lat lon points for map in PostGIS

I am interested in a PostGIS implementation of the R-based soulution from a previous question, How can I convert data in the form of lat, lon, value into a raster file using R? Currently, I am hoping ...
3
votes
1answer
495 views

PostGIS 2.0 ST_Transform with Rasters cannot find custom SRID

I'm trying to calculate an average value in a buffer around a point. Given a raster in EPSG 4326 and a similar point, this is fine, except that the values will be skewed as they are not projected in ...
1
vote
1answer
358 views

How to transform ETRS to EPSG?

I have data in the ETRS 89 LAEA format (SRID: 3035). But I have problems to transform it. Example data: N2736 E4541 I want to transform it to EPSG WGS84 (SRID: 4326), to check the coordinates on ...
2
votes
2answers
2k views

Getting a Bounding Box in Latitude / Longitude using PostGIS shp2pgsql

Using the PostGIS shp2pgsql -s 4326 ... I generated the sql file and created my spatially enabled table. When executing my query: select box2d(ST_extent(the_geom)) from feature_data; I'm returned ...
2
votes
1answer
505 views

Postgis: WGS84 Lat Lon Point to Gauss-Kruger 3

How do I convert a WGS84 lat lon point in postgis to Guass Kruger 3 (31467)? Somehow, I do not seem to get it right. I tried the usual way for converting projections: ...
6
votes
3answers
729 views

Retrieve polygon smallest MBR

I have a postgis table containing polygons. I want to transform my polygons to 4 points polygons : retrieve the smallest MBR. Here comes an illustration of what I want : My original polygon is ...
7
votes
1answer
1k views

How do I get a country border data set into my geography column?

I have a PostGis database with a multipolygon geography (as opposed to geometry) column. I'd like to fill it with the country border data available from ...
2
votes
1answer
441 views

How to convert SHP/POSTGIS data into x, y, z, “cost” data?

Is there a way to convert a line layer (shp or PostGIS) data into (x, y , z, cost) i.e. (From_node, To_node, optional_Elevation, Cost/Weight) ?