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
2answers
818 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
330 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
113 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
705 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
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) ...
4
votes
4answers
10k 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
2k 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
124 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
4k 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 ...
2
votes
2answers
761 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
546 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
655 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
503 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
2k 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 ...
1
vote
1answer
204 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" ...
1
vote
1answer
301 views

How do I create an index layer for multiple maps?

I am trying to create an index layer of just the area within the Orange lines. I am having difficulty creating this layer due to it not being a simple box area. The goal is to create a index layer, ...
0
votes
2answers
148 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
749 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 ...
22
votes
3answers
2k 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 ...
8
votes
1answer
4k 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
1k 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
224 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
1k 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
612 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 ...
5
votes
1answer
1k 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
1k 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
3answers
572 views

Does the NED use geocentric or geodetic latitude?

What kind of latitude does the National Elevation Dataset (NED) use? Geocentric or geodetic or something else? I can't find the information anywhere on their site (http://ned.usgs.gov/index.html) or ...
4
votes
0answers
292 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 ...
4
votes
2answers
456 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 ...
4
votes
3answers
584 views

Defining the appropriate Projected Coordinate System

I am a beginner at ArcGIS and have a technical question. I need to assign a projected coordinate system to my boundary/polygon data in order to calculate square miles. There are many to choose from. ...
3
votes
1answer
72 views

USA Contiguous Albers Equal Area Conic to miles

My data is in USA Contiguous Albers Equal Area Conic projection. How can I convert the USA Contiguous Albers Equal Area Conic projection to miles?
3
votes
2answers
139 views

methods for converting coordinate datum and format in python?

Related to an earlier Q&A of Missing grid shift files for cs2cs.exe? ... what are the various methods to convert coordinate datum and format in python? (Windows Vista, python 3.4) For example, ...
3
votes
2answers
65 views

Digital Elevation Model and Shapefile not aligned in openWind

I have a digital elevation model and a shapefile containing point features for the location of wind turbines. These two layers appear to be aligned in QGIS but when I open them in openWind, they are ...
3
votes
2answers
1k views

Where is list of Geographic Transformations in ArcGIS, and their areas of applicability?

I have some data in Provisional South American Datum 1956, and I need to project it to Web Mercator with WGS84 as the datum. When I use the project tool in ArcGIS desktop, it requires a Geographic ...
3
votes
1answer
1k views

getting the specified geographic transformation, or at least the GCS, of a data frame

First, the TLDR digest: I'm getting a bogus value from dataFrame.geographicTransformations on some machines; how do I get the correct value as shown in the properties dialog? and/or Given a spatial ...
3
votes
1answer
645 views

QGIS custom CRS for map of manufacturing shop floor

I'm working on a web app that shows a map of a manufacturing plant's shop floor. I've built it in Inkscape and QGIS, but when I try to load it into Tilemill, I get a CRS error. Specifically, it ...
3
votes
2answers
391 views

How do you change the prime meridian of a map?

I am working with the Natural Earth world map as a SHP file, but when I try to change the prime meridian (PRIMEM) of the coordinate system ...
3
votes
1answer
3k 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 ...
3
votes
1answer
519 views

Why are the formats of these coordinates different?

I'm really sorry if this is a silly question (and I'm sure it is) but I have tried searching but I am a complete newbie to coordinates and maps and I don't know what I'm looking for so am not finding ...
2
votes
0answers
83 views

QGIS 2.8 Raster Layers Moved [duplicate]

I recently downloaded QGIS 2.8 and opened an existing project in it to check how it handled it and make any changes required. This project includes several raster heatmap layers. My problem is that ...
2
votes
1answer
82 views

PostGIS GML round trip confusion

I've investigated the issue of coordinate order in GML and each time I think I've got it but I find my self confused once again. I think some of my confusion may be to do with PostGIS. Doing a ...
2
votes
2answers
109 views

Choosing country projections

Anyone know of a good reference (either pay or open-web) that details recommended country projections?
2
votes
1answer
1k views

How to calculate grid convergence (True North to Grid North)?

I would like to know how to calculate the grid convergence angle between True North and Grid North for UTM maps. I am using ArcGIS 10.0 (ArcView licence) and have used the Calculate Grid ...
2
votes
1answer
193 views

Dealing with raster: creating it in projected CRS and exporting it in geographic CRS

When creating a raster from a polygon (the CRS of the polygon is a geographic coordinate system), the raster is created in the projected coordinate reference system of the data frame, which is a ...
2
votes
2answers
225 views

Geodetic lat/lon to ECEF cartesian: Direction to apply geoid undulation from ellipsoid surface?

I'm working on modeling the earths surface in 3D, using a combination of WGS84/EGM96 and NASA SRTM orthometric height data. To calculate a final cartesian XYZ coordinate for a point on the earth ...
2
votes
1answer
171 views

How to find the projection of an image?

Instead of georeferencing the image and deforming it, I'm trying to find the projection used by the author of the image. I've got tens of these distribution maps to digitize. The idea is to avoid ...
2
votes
2answers
177 views

which map projection should be used for global map with geography and human demographics

I am working on a project to try to identify the most threatened populations (on a global scale) of having a limited access to freshwater. I want to compare those most at risk currently and then add ...
2
votes
1answer
137 views

Can you create a CRS of superseded NSW Datum

I want to use a superseded projection (NSW integrated survey datum - referred to as ISG) because my main client utilises it. The projection is based on AGD66. We regularly receive survey files in this ...
2
votes
3answers
304 views

Geodesic measurements for short distances throughout US?

My ArcGIS experience has been limited to working on large-scale maps with planar projections. I'm moving to a project in which I want to calculate the distance between pro sports facilities throughout ...
2
votes
5answers
536 views

Is latitude / longitude a universal coordinate system?

I hear people complain: my biggest gripe with google spatial apis is that they hide the fact that latitude/longitude is not a universal coord system My question is Is latitude / longitude a ...