Tagged Questions

The process of translating a map or spatial data from one geographic projection to another

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40
votes
8answers
1k views

One dimensional map of the world?

Bit of a strange question but hope this is OK to ask here. Has anyone heard of a '1-dimensional' projection of the world map - that is mapping all the points on the globe to a single line? I was ...
15
votes
5answers
5k views

Map projection in OpenLayers

I want to overlay some data whose projection is WGS-84 on Google map layer in OpenLayers. But I just can't make them in the right place. I did as follows: map = new OpenLayers.Map('map', { ...
14
votes
1answer
498 views

What is the most accurate coordinate system for calculating areas of polygons?

I have multiple polygons, all located offshore around the UK. I am trying to calculate the areas of these polygons in square kilometres, without splitting them by UTM zone. Is it possible to do this ...
12
votes
3answers
5k views

Layers having the same coordinate system should overlap, but they don't. What's wrong?

I put 4 different layers into my ArcMap document, but only one of them will show up on the map! I should be seeing the other 3 layers as well. When I do a Zoom to layer, I can see one layer, but I ...
12
votes
4answers
1k views

Does Re-Projecting an ESRI ShapeFile only update the content of the .prj file?

if i wish to change the projection of some shapefiles from .. lets say NAD83 (4269) to WGS84 (4326) ... and by using some 3rd party app .... does this mean the .prj file is only updated .. and not the ...
10
votes
1answer
724 views

Projecting sp objects in R

I have a number of shapefiles in different CRSs (mostly WGS84 lat/lon) that I'd like to transform into a common projectly (likely Albers Equal Area Conic, but I may ask for help on choosing in another ...
9
votes
10answers
4k views

Batch convert lat longs to UTM?

I've got a .csv file that contains a long list of latitude and longitude points. Is there an efficient way to batch convert the list into a projected UTM coordinate system? Thanks.
8
votes
4answers
880 views

How to reproject all geometries in a PostGIS table?

I created a spatial table with SRID:4326. Now I want to change total projection to SRID:32644 into a new table. The old table should remain unchanged.
8
votes
5answers
3k views

ArcGIS/ArcPy Python, how to get latitude and longitude of a projected point?

I have a point feature in a feature class that is being accessed by ArcPy. The point is projected but I need to find an efficient means to get the unprojected latitude and longitude for this point. ...
8
votes
1answer
170 views

Reprojection - Learning the ins and outs

I would like to expand my knowledge coordinate systems, projections and reprojecting data, with a view of writing a reprojection engine. Could you provide me with some resources (books, websites, ...
8
votes
1answer
271 views

How can I see the coordinate transformation parameters in QGIS?

How can I see (and edit if possible) the transformation method and parameters used by QGIS for "on-the-fly" transformation, and then for saving data in another CRS? Like in ArcGIS? Here is the ...
7
votes
2answers
7k views

How to enable projection transformation in QGIS

My QGIS project has two layers, one layer is retrieved by Google layer plugin which fetches the static Google map image whose CRS is +proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 ...
7
votes
1answer
193 views

Looking for US National Grid to Lon/Lat Converter in Python, C, or C++

I see here that there is Fortran source code for going from USNG to lon/lat: http://www.ngs.noaa.gov/PC_PROD/USNG/ Is there some python or C/C++ code that does the same? My understanding that this ...
6
votes
2answers
269 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 ...
6
votes
2answers
2k views

Derive WGS84 Longitude & Latitude from British Northings & Eastings

I'm looking for a fairly simple way to append columns with WGS84 longitude and latitude to a table containing northings and eastings. The source data is Ordnance Survey's CodePoint Open, which I is ...
6
votes
1answer
628 views

Python script to convert Lat Long to ITM (Irish Transverse Mercator)

I am currently working on a python script that converts Lat Long (WGS84) to ITM. The formulas used are based on a paper published by OSGB (Appendix B): ...
6
votes
1answer
156 views

Coordinate system in aerial imagery

I am calculating WGS84 coordinates of points in an aerial image, given the WGS84 coordinates of the center of the image and the ground distance width and height (calculated from altitude and lens ...
6
votes
1answer
82 views

Should I Reproject Data Which Has Been Captured Incorrectly?

I'm working on a project for a client which is migrating data from an Oracle database to an ESRI Geodatabase. When data for this project was initially captured over 15 years ago, the coordinate ...
5
votes
4answers
599 views

Given long, lat, x and y, how do I find the projection?

I am using an app called farsite that outputs shapefiles that show how forest fires will grow. I am getting output in coordinates as X and Y values rather than (lon,lat) and am looking for a ...
5
votes
2answers
3k views

Converting X,Y coordinates to lat/long using pyproj and Proj.4 returns the wrong coordinates

I'm writing a python script that reads multiple XML files containing x and y coordinates and combines them all into a single csv file. Latitude and Longitude are required fields in the csv, but I am ...
5
votes
2answers
1k views

How to use ArcObjects to choose GeoTransformation?

I’m currently building a Desktop add-in tool with ArcObjects that: Asks a user to select a feature class Reprojects the feature class to Web Mercator Executes some geoprocessing The initial ...
5
votes
2answers
649 views

How to set a map's extent to the envelope in miles

I want to set extent of the map into envelope which sizes are defined by user in miles(kilometers, whatever human readable unit). How to make it? I wrote the following code: static void ...
5
votes
1answer
643 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
1answer
491 views

How to reproject a raster file in QGIS with datum transformation?

I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
5
votes
1answer
172 views

How to reproject a raster in QGIS?

I am a history teacher and I like to make my own maps (I can never find exactly what I want). I am using QGIS 1.8 and Natural Earth data. I want to reproject their cross-blended hypso rasters into ...
5
votes
4answers
858 views

Changing image projection using Python

Image corner coordinates are known: Top left: (70.20315, 20.92749) Top right: (70.20315, 31.45240) Bottom left: (59.70571, 20.92749) Bottom right: (59.70571, 31.45240) (Basically map over Finland ...
5
votes
1answer
194 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
348 views

Custom Geographic Transformation on QGIS

Is there a way to create a custom geographic transformation with specifics parameters in QGIS like in ArcGIS? Okay, I want to tranform SAD69 system into WGS84. Well, I'm in doubt because in ArcGIS ...
5
votes
2answers
3k views

Convert x, y position in georeferenced image (with world file) to longitude, latitude?

What steps do I need to do in order to calculate longitude and latitude for a specific pixel in a georeferenced image? For example this image ...
4
votes
2answers
2k views

What is the difference between EPSG:900913 and EPSG:3857?

I'm using the QGIS google layers plugin to digitize a parcel as a shapefile. Later I want to import it to PostGIS. I know that google maps use a special 'google mercator' projection. What is the ...
4
votes
3answers
656 views

How can I find out how to convert this point to lat lon?

I have received a shapefile with measurement points to be analyzed, but no matter how I try, I can't find how to convert to lat lon. I suppose it would be good to know the projection but when I look ...
4
votes
2answers
240 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
5answers
1k views

Can I copy an entire geodatabase with relationship classes and domains and reproject all feature classes from wgs84 to state plane?

I have an SDE geodatabase with several feature classes, tables, relationship classes, and domains. All the feature classes are currently in WGS84 coordinate system. I need an exact copy of the ...
4
votes
2answers
2k views

what is the best way to programmatically convert between WKT and Proj4 string?

some shapefiles have a .prj file associated with it. and the .prj file contains the projection info of the shapefile in the format of WKT. Sometimes I need to convert WKT to proj4 string, and ...
4
votes
2answers
3k views

Basic proj4 conversion UTM grid -> longlat and back

I'm a GIS novice, and am struggling to understand how to drive proj4 to accomplish what seems like a simple thing. I've googled for a couple of days, but everything I find seems to presuppose quite ...
4
votes
1answer
605 views

How to do stereographic projection conversion (w.r.t. changing point of projection)?

Given a stereographic point P1 projected from point P, and given another point Q, I would like to know how to transform P1's coordinates to that of a stereographic point Q1 projected from point Q. ...
4
votes
3answers
69 views

How to transform FileGDB featureclasses from custom local coordinate system?

Background: Started working for company that is in middle of system-wide IT upgrade including GIS data. Existing in-house data is in a FileGDB, is in an assumed coordinate system and represents 1000 ...
4
votes
2answers
278 views

How to register shapefiles to an image?

I'm generating images from various sources and the projections are not necessarily known ahead of time. The images are subject to interpolation and other alterations while being rendered, but I can ...
4
votes
3answers
3k views

Using the Proj4js library to convert from Google Maps to projected values

I'm using the proj4s javascript library (based on advice from this question I asked previously) to convert lat/long values on my webpage. This page receives the lat/long values from google maps and ...
4
votes
1answer
74 views

How to properly assign spatial reference to converted AutoCAD data?

I know this is a frequent problem, I myself confronted with this problem many times, yet somehow each Autocad dataset I received is different (although they're from the same area). To some data, the ...
4
votes
2answers
788 views

How to unproject WKT to WKT in .NET?

I have WKT in this format: GEOMETRYCOLLECTION(POLYGON((491990.250718 6212873.59755,491492.160493 6212904.94117,491265.64715 6212790.54445,491319.517251 6212550.36334,491579.624164 ...
4
votes
3answers
1k views

reprojecting geotiffs to spherical mercator using gdalwarp

I would like to reproject raster images (tiffs+proj+tfw) files too "google's" projection using gdalwarp. From what I understand, google uses epsg:900913/epsg:3785. What I don't know is how to ...
4
votes
2answers
403 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 ...
4
votes
2answers
209 views

How to Intersect a layer with custom CRS with NED data?

I am trying to create a map with a layer of county tax assessor property parcels plus NED elevation data. The projection of the tax assessor layer is a weirdo -- looks like user-created by the ...
4
votes
0answers
69 views

How much error in a transformation?

I've been working in GIS for about a year and have a functional grasp of Projections and Transformations from within ArcGIS (10.0). Geosoft Oasis is another program we use. In working with our data ...
4
votes
0answers
206 views

How can I improve my Georeferencing results?

Background This is my second question related to georeferencing naked raster maps in order to re-visualize them on different coordinate systems and in conjunction with other data layers. The previous ...
4
votes
0answers
147 views

NAD83 and NAD83 State Plane

I'm struggling with a projection question. I have some data in California State Plane and am trying to align a NED with NAD83. I thought these would just natively align, but they don't seem to ...
3
votes
2answers
847 views

How to reproject a vector layer in QGIS?

I have some shape file which is in UTM. I wanted them to convert to Decimal Degreesin QGIS. Hope I can get some better response.. Thanks.
3
votes
2answers
182 views

Equally sized countries?

Is there a map projection (or a more appropriate term) which allows you to see every country as an equally sized land area, but positioned approximately in the correct geographic position? Water ...
3
votes
1answer
52 views

Why does FME Reprojector create coordinate values 0?

I'm using the NeighborFinder transformer in FME Desktop 2013, and I need it to use a maximum distance in meters. My input data, however, are points and lines in WGS84, so before sending them into the ...

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