A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane

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2
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1answer
142 views

Valid values of mollweide projection in QGis

i just imported a vectorlayer (without any reference points) to qgis as mollweide projection to save it to longlat. What i am wondering about is a mathematical problem: Not every x,y coordinate on the ...
2
votes
1answer
448 views

Does ModelBuilder need to use variable to define projection and then re-project?

I am trying to build a Model in ModelBuilder to create two different process raster datasets: One set is to define a raster dataset to set a WGS 84 projection; and then the second set is to take ...
2
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1answer
65 views

Hölzel projection - prj.file

Is there a prj-file-defintion available for the Hölzel-projection? (http://dl.maptools.org/dl/libproj4/manual.pdf#page=58, page 58)?
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2answers
905 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 ...
8
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2answers
611 views

How to get a “classical” globe projection

I have a shapefile of the world continents in EPSG 4326. To what reference system do I have to reproject my file to get a projecting like this globe below?
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0answers
50 views

Problems with projections in QGIS 2.2 on a Windows Vista? [duplicate]

I use QGIS 2.2 on Windows 8, and the same QGIS 2.2 has been installed on a computer with Windows Vista. On the Windows 8 everything works just fine, but something is wrong on the Windows Vista. All ...
1
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1answer
112 views

Geoserver Reprojection Results in Northerly Shift Compared to GDAL

I have data in a postgresql data store in EPSG:2163 and am displaying that using OpenLayers in EPSG:3857. This results in a ~25 km northerly shift when displayed either in QGIS or OpenLayers. To ...
2
votes
1answer
66 views

Is there general Earth Projection in ArcGIS for Desktop?

I'm starting a new personal project and I need a little bit of helping on setting it up. First off I'm trying to determine the area of a rectangle that is 1 mile in width and the circumference of ...
1
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1answer
395 views

My class using ogr to calculate distance is returning incorrect results away from the equator

In an answer to this question ustroetz kindly provided some sample code for use of ogr to do lat/lon distance and point in polygon calculations. I've created a Python class based on his example to do ...
48
votes
4answers
8k views

Why has Web Mercator (auxiliary sphere) become the web map standard?

I understand what the difference is between the Web Mercator projection and Web Mercator Auxiliary Sphere (WMAS). I also understand that both Google and Esri have adopted this projection as their ...
0
votes
2answers
270 views

How to realign misplaced GeoTiffs?

I have bought a few (30) GeoTiff maps from my country's Geo-department - South Africa. They all have a date in the filename and the newest one was created in 2004, I see one is dated 1977 - that old! ...
2
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2answers
893 views

Older British Geological Survey geology maps of Kenya; need complete projection information

I have several geologic maps of Kenya produced by the BGS circa 1993. Noted on each map is the following: Projection:-Transverse Mercator Spheriod:-Clarke 1880 (modified) That's great, but that doesn'...
1
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2answers
668 views

Predefined Coordinate Systems missing in QGIS 2

in QGis 1.8 were lots of predefined coordinate systems (national projections). Where have they all gone in qgis 2.0? I specifically need the Gauß-Krüger-Projections Zone 1 to 5. Is there any plugin ...
0
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1answer
101 views

Hand-written coordinates from a Garmin NUVI

I've been asked to map point data that was collected in the field by manually writing down the coordinate from a Garmin NUVI 1490 LMT. They were put into a spreadsheet and sent my way which I was ...
2
votes
1answer
179 views

Why this two datasets don't match?

I have a postGIS database in SRS 4326 (WGS84) with several Europe layers working well, but when I load a shapefile projected to the same SRS with QGIS, the layers don't match. To explain it better I'...
5
votes
1answer
185 views

Azimuthal Equidistant - 40,000 Km range

I've been looking at making an azimuthal equidistant map. There are several web sites that offer to make one, based on my location, but they all have the same problem. They assume my antenna rotates ...
4
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0answers
35 views

Projecting polygon when calculating its area? [duplicate]

I have a broad range of polygons (in vector format and in SpatialPolygonsDataFrame class), some going east-west, others going south-north, while even others span polar regions or very large ranges as ...
2
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2answers
1k views

Spherical Mercator projection invented by Google and not conformal?

I had some certitudes on the Google Spherical Mercator also known under EPSG code 900913 and 3857 before looking at this presentation, I was sure that this projection was in the Mercator family (so ...
1
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1answer
753 views

How to create polygon that goes over +/-180 (dateline) in ArcMap?

I want to create a polygon feature that will go through the dateline (180 long.) in ArcMap. I am using WGS_1984_Web_Mercator_Auxiliary_Sphere (WKID: 3857) for my data frame and my polygonal feature ...
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2answers
658 views

Given a flight path given in latitudes and longitudes, how do I find another flight path that is parallel to the path given?

Given a flight route that is given in latitudes and longitudes, how do I find another route that is "parallel" to the route given (find a perpendicular line to each waypoint given)? I think the best ...
3
votes
2answers
562 views

ESRI projection to SRID?

I am looking at MapX and MapY coordinates. The docs say they are "truncated State Plane coordinates: NAD 1983 State Plane Louisiana South FIPS 1702 (US Feet)." I am trying to reproject into a common ...
2
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0answers
1k views

Projecting a Raster from WGS84 to planar Equal Area to Calculate Area: How to Select the Cell Size?

I have a broad question on how to calculate the 'correct' cell size for a raster when analyzing an area not at the equator. My goal is to project a land cover raster provided in GCS WGS84 to an equal ...
1
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1answer
670 views

Problem Overlaying layers in OpenLayers

I have a html page with 2 WMS layers. The first is one Base Layer , & the second is my personal WMS feature. I load it from Geoserver. The problem when I add the 2 layers I do not have the ...
6
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1answer
8k views

Openlayers and Geoserver: OSM/Google Maps and WMS Overlay

I am experiencing projection problems with the following set up: GeoServer with ESPG:4326 based shapefiles (*.shp) OpenJump to edit my shapefiles Openlayers with EPSG:900913 base layers GeoServer ...
4
votes
1answer
638 views

How to convert a png with known bounds from Plate Carree to Mercator with GDAL

I have a png image that shows the region defined by the geo bounds UpperLat, LeftLon, BottomLat, RightLon (in degrees & -ve for West Lon and South Lat) in Plate Carree EPSG:4326. I want to convert ...
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1answer
114 views

Why are some layers saved with custom CRS while others use the appropriate EPSG code?

I have a number of .shp's that I have converted from EPSG 4148 to CPNO27. Some have come out perfectly and others revert to EPSG 1000007. I have checked and the only difference between the two is the ...
3
votes
0answers
92 views

Is it possible to render tile-based web mapping projects in any other projection than web mercator?

Web-mapping technology has to a large degree adopted the web-mercator projection as the standard projection for displaying geographic objects with interactive map-clients. This is due to many factors ...
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0answers
72 views

Add a raster specifying the projection in pyqgis

I would like add an raster but I want to specify the projection. If I do : qgis.utils.iface.addRasterLayer(url,layerName) QGIS ask me to specify the projection. I want to this with python. How I ...
5
votes
2answers
2k views

How to convert NAD 27 to WebMercator in using the ESRI Silverlight API? (C#)

I am working with the ESRI Silverlight API. I found THIS post in the ESRI forums and THIS OTHER which show how to convert between WGS84 geographic coordinates and WebMercator coordinates. I want to do ...
1
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1answer
408 views

Convert decimal latitude/longitude bounding box to SRID 26910

I have a bounding box specified in decimal latitude/longitude, and need to convert this into a bounding box in the SRID 26910 coordinate system. I've never had to work with different GIS co-ordinate ...
2
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0answers
68 views

Is it safe to store coordinates on NFC tags always in one CRS and rely on conversion for others

I'm involved in NFC (Near Field Communication) standardization of a record structure for geographic point locations. That will allow to put coordinates on NFC memory tags which can be read with a ...
1
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1answer
114 views

OpenLayers Projection and Datum Question

I had a conversation with a co worker that was asking about an OL map I am developing. She asked me what the 'projection' was and I said EPSG:4326. She didn't know what that means, so I said it's ...
-2
votes
1answer
136 views

Buffer is giving me a different distance [closed]

I'm using ArcGIS 10.1. When I Buffered I changed the environments to compare the two different projections. WyLAM is a statewide Lambert Conformal Conic projection used for Wyoming. State plane in ...
0
votes
1answer
43 views

Shorcut to apply selected shapefile projection to the data frame in arc gis

What is the shortcut to apply selected shapefile or the newly added data's projection to the data frame in arc gis, well not the traditional way of Dataframe--->Properties--->CS system "This could be ...
0
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0answers
49 views

I want to reproject data from 0-360 to -180 - 180 [duplicate]

I've been downloading data from NOAA in a CRS that goes from 0-360. The rest of my data is in -180 to 180. What's the easiest way to reproject or shift the data in QGIS? It took 30 seconds in ArcMap, ...
0
votes
1answer
408 views

Is it possible to use JTS for calculations on data in geographic coordinates?

I have some spatial data that has all of its coordinates as lat/lon pairs (with about 10 digits decimal precision), it's stored in a database as WGS84 data. Some of the data is represented as polygons ...
-3
votes
1answer
80 views

Why is it important to ensure that the shapefiles have a spatial reference system when created?

Why is it important to ensure that shapefiles have a spatial reference system when created?
1
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1answer
557 views

How to automatically transform between base layer and vector layer in OpenLayers

I have a simple example on http://jsfiddle.net/29bsw/ I have a map with an OSM layer as base layer and an additional vector layer. The projection of the map is defined as EPSG:900913 and the ...
0
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0answers
17 views

Adding a Z Unit [duplicate]

I'm struggling with the Z Unit conversion of some data. Both the NHD data and my DEM are in a GCS with Decimal Degrees. These data sets project perfectly on the fly, but after I adjust the Z Unit of ...
1
vote
1answer
456 views

Adjusting Z Units on a DEM

I am learning how to use ArcHydro and attempting to change the Z Units because I get a warning message saying the Spatial Reference Doesn't Match. The DEM was in Meters, and I adjusted the Z Unit to ...
0
votes
2answers
211 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 ...
5
votes
2answers
2k views

Stereographic projection of WGS84 ellipsoid on a plane[python]

I would like to ask you for help in following task. What I need to do is to derive local x,y coordinates from latitude, longitude, applying stereographic projection of WGS84 ellipsoid on a plane, when ...
1
vote
1answer
219 views

I have a WKT How can i put it to MAPINFOW.prj file [closed]

I have this WKT file: PROJCS["PRS92 / Philippines zone 3" ,GEOGCS["PRS92" ,DATUM["D_Phillipine_Reference_System_1992" ,SPHEROID["Clarke_1866",6378206.4,294.9786982138982]] ,PRIMEM["Greenwich",0] ,...
0
votes
1answer
162 views

Determing which Which georeference system was used on an Ecuadorian Topo Baselayer

I'm creating a map in Western Ecuador, and am attempting to use a military topo baselayer for it. The map comes with UTM grid lines on it so georeferencing it was easy but I'm unsure of what ...
0
votes
1answer
53 views

Assign Projection to multiple shapefile

I have multiple shape files in a folder. I want to assign projection to all the files inside the folder at one go. In batch file i am able to assign projection to all the shapefiles, but i want to ...
1
vote
2answers
128 views

Define a projection for one point

I'm new to ArcGIS and am using ArcMap 10.1. I wanted to find the distance from a point (lat 36N long 12E) to all the polygons in my shape file. People on this forum helped me out and said that I ...
1
vote
2answers
670 views

Why does Transverse Mercator projection have scale factor?

Why does the Transverse Mercator projection have a scale factor in ArcGIS and the standard Mercator projection not? In other words what is the difference between these two projections beside being a ...
0
votes
0answers
27 views

QGIS - unable to change projections [duplicate]

I am relatively new to QGIS (version! 2.0.1) and having trouble changing projections. No matter what I choose the view is the same. For example, in the attached screen shot I have chosen Alaska Albers ...
0
votes
4answers
501 views

Buffer in QGIS/R is 650-670 m wide instead of 500 m

I am trying to make a 500 m buffer for my polyline layer. Unexpectedly, I receive buffer varying from 650 to 670 m, depending on location. As many resources recommend to use UTM before making a buffer,...
2
votes
1answer
111 views

Equal (ish) areas Map Projection at the Tropics

What map projection (non-interrupted) preserves areas well for the entire tropical region? I am thinking of using a Cylindrical Equal Area or a sphere based version of a Cylindrical Equal Area or ...