Tagged Questions

1
vote
1answer
43 views

Geometry has incorrect latitude-longitudes

SELECT ST_SRID(geom) AS s FROM zones GROUP BY s; returns a single record: 4326 SELECT Find_SRID('public', 'zones', 'geom'); returns 4326 SELECT AsText(geom) FROM zones returns geometry like: ...
0
votes
1answer
27 views

How can I find the SRID from the WKT out of a GRIB file?

I have a grib2 file which I'm trying to import into PostGIS 2.0 Raster and process. Trouble is, I can't figure out what the SRID is supposed to be, or one close enough for government work. Running ...
2
votes
1answer
61 views

Calculating points in the USDA's Cropland Data Layer coordinate system

I need to integrate against the USDA's cropland data layer. They've got a demo and some API docs. The important query I need to run is this, given an (x, y) of say (1551459.363, 1909201.537): ...
0
votes
1answer
73 views

Openlayers Linestring over edge of map

im trying to create a route displayer for ships. But im struggling with the edges of the map. When going from ie. 179* to 2* it displays a line across the entire map, instead of displaying it on the ...
0
votes
0answers
12 views

Units of Geometry & Geography data type [duplicate]

When you store data using the Geography data type (like in PostGIS), is it always in lon/lat in degree decimals? For the Geometry data type, what are the units used in the coordinate pairs? Can it ...
1
vote
2answers
157 views

What Spatial Reference System do I store Google Map's Lat/Lng in

I am new to PostGIS, Spatial Reference Systems and projections and want to store lat/lng coordinates retrieved from Google Maps and Openstreetmap and its services like the Geocoder/Nominatim. I'm ...
2
votes
1answer
52 views

How to bulk import ESRI projections into Postgis

Where can I get a file that would allow me to bulk upload all of the ESRI projections into the spatial_ref_sys table of postgis. I know that you can get insert statements on spatialreference.org; ...
1
vote
1answer
620 views

Convert latitude longitude coordinate to x y coordinate?

I'm using a postgis database and java to develop my application. I need to transform my geographic data currently in latitude/longitude format into a x/y format. I found solutions based on UTM ...
1
vote
1answer
318 views

SRID 4326 and geometry conversion

From this line: SELECT ST_AsEWKT(geom) FROM buildings LIMIT 1; I get this result: "SRID=4326;MULTIPOLYGON(((404269.308014269 4543087.6184561,...)))" I'm wondering if the coordinations are ...
0
votes
1answer
67 views

Why does Find_SRID return zero?

using SELECT Find_SRID('public', 'myTable', 'myColumn'); I get zero as the result, what does it mean? Regards,
3
votes
1answer
131 views

extracting pixel value from a table in postgresql

I have a table in postgresql that contains ID, row number, column number, pixel value and centroid of the pixel in WGS84 lat-lon system(4326). How could I extract the pixel value by giving a point in ...
2
votes
0answers
225 views

PostGIS: ST_Transform function conversion problem

I'm inserting map data from a GML file with srid EPSG:27700 into a PostGIS database table with srid EPSG:4326. I'm using the ST_Transform function as in this snippet: ...
2
votes
2answers
151 views

Ordnance Survey osgb:BNG spatial reference system not recognized by PostGIS

I'm trying to load an Ordnance Survey GML file into PostGIS using the ST_GeomFromGML function. The problem is that the spatial reference system that is used in the file, osgb:BNG, is not recognized by ...
8
votes
2answers
649 views

How can I convert geomagnetic coordinates to geographic coordinates without doing the math myself?

I have some data which are in geomagnetic coordinates; that is, they are latitude and longitude, but in reference to the magnetic north pole in Canada rather than the geographic north pole. As you ...
5
votes
2answers
538 views

What is the SRID of census.gov shapfiles?

I downloaded the county files from: http://www.census.gov/cgi-bin/geo/shapefiles2011/main I cannot figure out what SRID to use with them. When I am trying to generate a class file from ./manage.py ...
1
vote
1answer
74 views

Which SRS is computational more effective to store continental scale data? (given some conditions)

For a Precision Agriculture application I need to make calculations in UTM projection. The data will be stored in Postgis and is made of soil samples results (point data) and field boundaries of many ...
3
votes
1answer
771 views

How to get the coordinate system from a PostGIS database?

My question is probably amazinlgy stupid, but I can't find the answer myself. I would like to extract from a database the latitude and longitude of points. For now, I'm getting x(the_geom) and ...
6
votes
4answers
425 views

Where should I start advanced GIS learning

I am relatively familiar with most of the GIS stuff. I develop GIS applications as well with open source offerings. Still I find some lapses in my theoretical knowledge in GIS. What resources can you ...
15
votes
5answers
2k views

How do you best deal with data that spreads across UTM Zones?

I have data that spreads across two UTM Zones GDA/MGA94 UTM Zone 55 and 56. I have layers such as a cadastre, roads, pipelines etc where I want to store measurements like lengths and areas in metres ...