0
votes
0answers
5 views

Clustering the WGS84 point features (projection transformation aspects)

My question is quite trivial and was discussed many times before (like here) but in our case it has the confounding extra requirements... The list of sparsely distributed 2d point features is stored ...
2
votes
1answer
43 views

PROJ4 / PostGIS transformations between WGS84 and NAD83 transformations in Alaska

I'm trying to implement the recommended WGS84 - NAD83 transformation for Alaska using PostGIS. This post: Geographic Transformations in Alaska Between NAD83 and WGS84 indicates the proper ...
-1
votes
2answers
317 views

Convert geometry to latitude-longitude using PostGIS ST_Transform

My table has a geometric field, in EPSG:3857, of type point. I need the latitude and longitude, in EPSG: 4326, of each point. Could someone give me a valid example of how to use ST_Transform().
3
votes
2answers
76 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
86 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
63 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
147 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
3k 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
92 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
379 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
478 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
552 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 ...
2
votes
1answer
423 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
546 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
784 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
2k 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
443 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) ?