A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions.

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5
votes
3answers
630 views

How to define layer's CRS and avoid the CRS dialog in PyQGIS?

There is an existing Shapefile, which I want to add. At the moment my code looks like: self.iface.addVectorLayer(self.shpFilePath, "Track", "ogr") It works fine, but i want to define the crs ...
4
votes
3answers
9k views

Which CRS to use for Google Maps?

I am trying to map a Shapefile (download) onto a Google Map using the Javascript API. The Shapefile describes the boundaries of NYC School Districts. The file's projection was Lambert Conformal ...
4
votes
1answer
7k views

Converting geographic coordinate system in R

I have points in geographic coordinate system and I wanted to convert them to swiss grid (CH1903+). Sample data: id lon lat 2 7.173500 45.86880 3 7.172540 45.86887 4 7.171636 ...
3
votes
2answers
2k views

What is the process to calculate Helmert parameters?

I have some double points (the same points in 2 different datums). I'd like to calculate the Helmert parameters but I don't understand how. NOTE: I don't need software. I need an algorithm in order ...
3
votes
1answer
220 views

Why not measure elevation from the center of the earth?

In trying to understand Geoid vs Ellipsoid height, I ran across this page. One of the claims is: Zero elevation as defined by Spain is not the same zero elevation defined by Canada ...
24
votes
3answers
3k views

What was the rationale for the non-standard UTM zones near Norway?

UTM zones 30V, 31V, 32V, 31X, 33X, 35X, and 37X do not line up with the rest of the UTM zone grid. Why was this allowed? According to Wikipedia, UTM was developed by the U.S. Army Corps of ...
6
votes
2answers
2k views

Describing a coordinate system in arcpy

I have a python script in ArcGIS 10.1 which takes in a few inputs from the user. One of the inputs is a coordinate system. I would like to test whether the coordinate system the user chose was ...
3
votes
1answer
102 views

Difference between datum and ellipsoid for geodetic coordinates?

Looking at the Wikipedia page for the North American Datum, it seems to imply that the datum is completely defined by the ellipsoid, which defines the major/semi-major axes, flattening, etc. For ...
2
votes
1answer
238 views

How to access Leaflet EPSG:3857 coordinates?

I read everywhere that Leaflet is internally using a spherical web mercator (EPSG:3857), but whatever I try I get either Lat/Lon (EPSG:4326) or strange coordinates I dont understand: ...
2
votes
1answer
143 views

Coordinate system doesn't contain values in the range -180 to 180 and -90 to 90

I'm creating an android version of a PC program (I've contacted the company who owns the PC program, so it's legal). The program is in the core a GPS, but is used to navigate pre-defined routes for ...
12
votes
3answers
5k views

Official term for latitude longitude coordinate system?

May I know what is the correct specific term for latitude longitude coordinate system? With "Geographic Coordinate", it seems to be a general term for every other system?
9
votes
2answers
878 views

What happens to feature class when importing to feature dataset?

I am creating a model that needs to ensure that all input datasets end up in the same coordinate system (among other things). I was originally going to batch project all of the datasets whether they ...
9
votes
2answers
3k views

Measuring distance in spherical Mercator vs zoned UTM

I've got points in WGS84 lat/long and I'd like to measure "small" (less than say 5km) distances between them. I can use the haversine formula from http://www.movable-type.co.uk/scripts/latlong.html ...
8
votes
2answers
1k views

Is there a standard for the specification of .prj files?

We use shape files for data exchange. I've looked at the .prj files: different programs produce different prj files. Is there a standard how the parameters must be specified in a prj file? AFAIK the ...
7
votes
2answers
917 views

How to Georeference Photos With No Spatial Reference?

I have about 100-200 field ground shot photos I would like to overlay in ArcGIS 10 that have no spatial information which I need to somehow develop using a photogrammetric formula. The camera was ...
7
votes
2answers
7k views

How do I convert affine coordinates to lat/lng?

I am extremely new to GIS. I'm using gdal to read in a landuse/landcover map and I need to pick out the lat/lng of certain land cover types to index into a different dataset which is expressed only ...
6
votes
2answers
1k views

How To Use Tiled Map Services with Different Spatial References in ArcGIS API for JavaScript?

I have the following code fragment in an esri page to try and change basemaps, the following code works, unless the next basemap layer uses a different spatialreference. if (baseMap) ...
5
votes
2answers
1k views

Does anyone know the proj4 Coordinte Reference System command line for Rectangular Polyconic Gores?

I am a GIS beginner using QGIS 1.8.0 I am trying to transform a world map from the standard WGS84 Coordinate Projection System to a set of rectangular polyconic gores, with a gore count of 12. ...
5
votes
1answer
2k views

MGRS in OpenLayers

I am trying to view the Military Grid Reference System coordinates in Openlayers through the MousePosition control. Is there an easy way to accomplish this just through Javascript? I am looking at the ...
5
votes
2answers
965 views

Quick way to determine if facing a given lat/lon pair with a heading

I'm looking for a fast way, preferably without trigonometric operations (just multiply, divide, add, sqrt and subtract) to determine if a point is visible. E.g. say I am facing 0 degrees N, I am at ...
4
votes
1answer
34 views

What is the level of error I should expect when using a NAD StatePlane CRS from an adjacent state?

I am adding Georgia data to my GIS database and, unlike the California data I've added, have decided to use my existing EPSG:3361 (South Carolina StatePlane) coordinate reference system for ...
4
votes
1answer
652 views

How to properly open an ASTER data?

Yesterday i downloaded an Aster L1B image from USGS's website. If i load it in QGIS, it doesn't get displayed properly(location wise). Even after i've enabled "On the fly" option, it's not reading the ...
4
votes
0answers
181 views

What projection system is used in China which is aligned with WGS84 [closed]

I have some GPS tracks in Beijing. I want to project it and convert the lat long degree values in meters for calculation in euclidian space. I was wondering what is the most suitable coordinate and ...
4
votes
2answers
3k views

QPJ files on ESRI software

We have some GIS data, which was converted from AutoCAD dwg to TAB using mapinfo, then converted to shapefiles as that's what we are required to create. Editing the data fields was done in the shape ...
4
votes
2answers
841 views

How to represent an imaginary flat world in QGIS without using a round-world CRS

Like one or two other users, I'm interested in using QGIS to map an imaginary flat world. A previous answer suggested simply refraining from defining a CRS for such a world, but I cannot seem to make ...
4
votes
4answers
13k views

Getting shapefile in right projection using ArcGIS Desktop? [duplicate]

I have an older map that I didn't create. I'm just trying to get everything to line up on it, and having a hard time. The data frame is in NAD_1927_UTM_Zone_12N, as are the point shapefiles (derived ...
4
votes
2answers
3k views

ogr2ogr srs options: where is the well known definition determined?

In the ogr2ogr documentation it says that when using -a_srs srs_def: Srs_def can be a full WKT definition (hard to escape properly), or a well known definition (ie. EPSG:4326) or a file with a WKT ...
3
votes
1answer
138 views

Rhombus shaped pixels when viewing an image referenced in WGS84

Following the Question What is the projection of WGS84 in GIS software?, in the comments section of the answer http://gis.stackexchange.com/a/73578/5256, Jake very well explains that Because the ...
3
votes
1answer
659 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
1answer
449 views

Programmatically Select a CRS in QGIS 2.4 using Python

When you run the following Python code in the Python Console of QGIS 2.4, uri = "file:///C:/data.csv?type=csv&xField=lng&yField=lat&spatialIndex=no&subsetIndex=no&watchFile=no" ...
2
votes
2answers
807 views

How to use the coordinate system in arcgis 10?

I have a favor to ask. I have a few layers. The layers have been made by a different company. So how do I combine them all together so that they have the same coordinate systems? If there are any ...
2
votes
1answer
739 views

How to speed up this simple MySQL points in the box query

MySQL doesn't have nearest neighbor search so. So I try to come up with a "distance" that's reasonable so the number of returned query is around 20-200. That way innodb doesn't have to compute ...
2
votes
2answers
656 views

What does 1:10m mean related to map resolution?

On Natural Earth they offer maps at various resolutions. What does 1:10,000,000 mean? Does it translate to the number of points per square meter or mile?
2
votes
5answers
3k views

Convert geographic coordinates to UTM zone 29N with Javascript

I have an issue converting lat longs to UTM with the ArcGIS javscript API. Lets say that I have a map, based on the UTM zone 29N, also known as WKID 32629. I have a known set of coordinates from a ...
2
votes
3answers
5k views

Code to convert WGS84 coordinates to British National Grid Easting/Northings

I'm looking for some code, ideally C#, to convert a WGS84 coordinate to British National Grid Easting and Northings. Does anyone have this to hand? I tried converting the Javascript code here: ...
1
vote
0answers
273 views

Query all Object within n kilometer Radius with Hibernate Spatial?

I use hibernate spatial attach a geolocation to a car. My card domain class looks like this: import com.vividsolutions.jts.geom.Point class Card { String name Point location } My program is ...
1
vote
2answers
600 views

How to fix shape file projections

I have a project with several shape files. The files overlapping however. I have to go to unusable extents to even see the file on the same screen. I have tried using to project to as suggested here ...
1
vote
2answers
9k views

How Can I change the projection of shapefile in Qgis?

I have a probleme with Qgis. I would like to change the projection of my shapefile, it's about caves in my country. The default projection is set to EPSG:3003, I want to change it to wgs84 EPSG:32632. ...
0
votes
2answers
192 views

Calculate length of line across zones with at least m accuracy

I have created lines between multiple points that are across MGA 54 and 55S (EPSG 28355). I am trying to calculate the distance between points but different methods give different answers (~1km ...
0
votes
1answer
882 views

How to calculate the UTM-Latitude-band?

I have to convert a coordinate from UTM to MGRS. I think I have the most of it covered, but I have some difficulties to calculate the correct Latitude-band. How can I decide which band the coordinate ...
8
votes
3answers
413 views

What coordinate system is this netCDF raster?

I obtained a netCDF raster file, but I couldn't get any metadata to get the name of the coordinate system the raster has been built on. The raster itself doesn't have any coordinate system embedded. I ...
8
votes
1answer
5k views

getExtent() in OpenLayers returns strange values

I'm trying to get the bounding box of the map area displayed by OpenLayers. I tried to use map.getExtent() because it should be exactly what I need, but the returned values are "strange": For ...
7
votes
3answers
2k views

Is there a name for 0,0?

Is there a name for the latitude/longitude pair 0,0? On a graph, (0,0) is referred to as the "origin" but I'm not sure if that term also applies to the location 0,0 in cartography.
6
votes
2answers
537 views

QGIS area calculation differs when on the fly CRS transformation enabled

When I open QGIS, add the layer, and calculate the areas of the shapefile via field calculator I get a different area than when I open QGIS and check "Enable on the fly CRS transformation" and ...
6
votes
2answers
860 views

Identify what projection this Australian map uses?

Im looking to put this map into google maps as custom tiles, but i now learn what projection is and that this map does not use the same format as google's default. You can create custom projections i ...
6
votes
2answers
2k views

Why do my Shapefiles not align correctly?

First: I'll summarize what I understand so far so please confirm or correct me. When On-the-Fly is selected a layer is re-projected from that of the layer's CRS to that of the project CRS, IF ...
5
votes
2answers
509 views

How to efficiently project datasets of varying coordinate systems into one coordinate system?

I am working on streamlining data processing at my organization. Currently we are using various large-scale Models that we will gradually bring into Python. The gist of our data processing is as ...
5
votes
1answer
2k views

How do I find the intersections of 2 circles on earths surface?

I have the circles' center in lat & long, as well as the radius in meters. How do I find the circles intersections? Edit: EXAMPLE: Circle 1: Center on Earth's surface (43.564627,-116.220524) ...
5
votes
7answers
2k views

Problem with Swiss coordinate system overlay in WMS

I have administrative boundaries data for communities in Switzerland from SwissTopo. Original data came in shape files with 'Bessel 1841 Hotine Oblique Mercator Azimuth Natural Origin' projection. ...
4
votes
0answers
316 views

Can GeoTools parse GML CRS definitions?

A kind of branching of this question. Soon I will need to handle GML Coordinate Reference Sysyem definitions in a Java servlet. Links: GML OGC reference. Concrete example. I know that GeoTools ...