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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138 views

Georeferencing uneven/irregularly gridded rasters

I'm trying to take a set of NetCDFs and turn them into georeferenced datasets using GDAL. However, the only Geospatial data is a set of 2-D lat/lon arrays. The projection type is not lat/lon. THe ...
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2answers
205 views

GDAL - Warping raster to new domain/resolution/projection causes data loss

I am attempting to warp a GTiff from a lat/lon projection to a higher (~2x) resolution Polar Stereographic grid. In the output GTiff any cells north of 64 deg lat become NaN instead of their actual ...
2
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2answers
164 views

Choosing country projections

Anyone know of a good reference (either pay or open-web) that details recommended country projections?
2
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2answers
530 views

What's the purpose of the reference latitude in Lambert Conformal Conic?

Going through flight school I got acquainted with the Lambert Conformal Conic projection, as it's the common projection for VFR sectional charts, and I think I have pretty good grasp of it, ...
2
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2answers
480 views

Tiled raster image to be placed in an OSM/ Leaflet.js map

I have a mapoverlay in a custom projection which I need to add as a layer to an Openstreet map within a website. Since I was not able to change the projection earlier, I decided to manipulate the ...
2
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1answer
594 views

Pyproj: converting WGS84 to Robinson

I have a WGS84 coordinate pair (37.7749295, -122.4194155). I have an image that is a Robinson Map Projection of the world. I'm trying to write a python script to locate my WGS84 coordinate on my ...
2
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1answer
280 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
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2answers
497 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
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1answer
135 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
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1answer
642 views

Why doesn't LeafletJS complete the conversion when re-projecting to Spherical Mercator?

When I use the Mapbox Leaflet pre-packaged Projection class SphericalMercator to project a lat/long coordinate into EPSG:3857 I have to multiply the result Leaflet provides by the earth's radius. ...
2
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3answers
517 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
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1answer
522 views

How do I set the projection and coordinate system for a TIFF file?

I have a topographic map of California (obtained from CAL-Atlas) as a TIFF file. I tried importing it into QGis, but it displays the map using a pixel based coordinate system rather than ...
2
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1answer
179 views

How can I get the ellipsoidal values for length and area using spatialite?

I have spatialite geometry data stored in a spatialite database in WGS 84 (EPSG 4328) format: SELECT Srid(geometry) FROM shape_layer; > 4326 When geometry is being returned as text, it is ...
2
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1answer
232 views

Miller cylindrical projection - central meridian

I'm new to projections topics and I've got a question that may be silly, but I hadn't found answer so far. I'm trying to use Miller's cylindrical projection for converting osm lat/lon to x,y values. ...
2
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1answer
350 views

Reprojecting Natural Earth dataset to World Eckert I

My question is connected with QGIS 2. Could anybody explain me how I ought to reproject the Natural Earth dataset there in order my world map to look correctly? When I strive to reproject these data I ...
2
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1answer
1k views

GeoTools and PostGIS with ESPG:3857

I'm trying to use both PostGIS and GeoTools with the same ESPG:3857 projection, however, it looks like the projections in PostGIS and GeoTools differ. This is what I have in PostGIS: PROJCS["WGS 84 ...
2
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1answer
128 views

Why does same image in two ArcGIS ArcMap configurations show different extent numbers?

I would like to get hear from you about the situation I am seeing here. What It got my eye was that when I download an ASTER from Reverb/ Echo from USGS website. At work, I load my ASTER file to my ...
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0answers
997 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 ...
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2answers
167 views

Digitized Shapefile manually using wrong projection: how to fix it?

I have a raster in correct projection. I used shapefiles, and marked objects (manually), but I found out that my vector layers have different projection, so they have different size and position. Is ...
2
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2answers
141 views

Is it possible to have another CRS in the status bar than used for the map?

I am new to QGIS. When I use OSM or Google Maps as a basemap via Open Layer Plugin, the map should be projected as EPSG: 900913. However, the Coordinates shown in the status bar are useless for me, ...
2
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0answers
224 views

Mercator projection that shrinks toward pole

I've noticed that lots of map viewer (especially those nautical chart viewer) will shrink a mercator projected chart while panning towards poles. Is this some compensation for mercator distortion? ...
2
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1answer
369 views

Problems with NAD27 projection in QGIS

I have some data that is in NAD27, but I am having a hard time displaying it in QGIS. I think that the problem is with the CRS. I cannot seem to find the correct NAD27 option. The closest one seems ...
2
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1answer
432 views

Converting map to use space oblique mercator projection using ArcGIS for Desktop?

I have a map document in ArcMap which I want to convert to using Space oblique mercator projection, but I am not sure if ArcMap supports it. Any hints on how to achieve this?
2
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1answer
485 views

Uploading unprojected shape files using GeoServer REST API

I have a number of shapefiles that lack the .prj file. I'm able to upload them to geoserver using the rest api. However, I'm unable to serve them after upload. Which brings me to the question as to ...
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2answers
865 views

How to transpose the lat/lon coordinates of a shapefile?

I need X to be Y and Y to be X (switching lat/long) within the polygon shapefile. If it were a point shapefile I know I could simply reverse the lat/long or x/y parameter and import from a table. I'm ...
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2answers
2k views

Converting google map api coordinates into meters

How would I go about converting the results of my map bounding box into meters within javascript? For example, if I have the coordinates 51.52366625446907, -0.07467269897460938 decimal degrees, can I ...
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1answer
90 views

Distance measure of ST_ClusterWithin

I use SRID 4326(WGS 84). So what is the measure of distance in ST_ClusterWithin . m, km, degree ? I ask it because in documentation it only says: geometry[] ST_ClusterWithin(geometry set g, float8 ...
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1answer
192 views

Projected raster data has inconsistent extent but not shapefile

I want to calculate the average value of a raster file within each polygon boundary of my shapefile. Because I want to preserve area I wish to use the Goode Homolosine (Land) projection. The original ...
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2answers
203 views

Defining coordinate reference system with rotation in GeoServer?

I am using GeoServer and have a layer in EPSG:900913 ("Google Mercator"). I need to "rotate" the map around certain point (say, 1500000, 7000000) by certain degree (say, 30 degrees clockwise). How ...
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1answer
97 views

Determining Projection using QGIS?

I am very new to QGIS and I am trying to determine the spatial projection and the units of distance of a certain raster file. The closest thing I can find is the CRS, which is set to some sort of ...
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0answers
229 views

Show a kml (which uses longitude and latitude EPSG:4326) in “google/OSM” projection (EPSG:3857) in open street map

I am showing a kml layer, over OSM. The points in the kml are latitude/longitude (EPSG:4326). I don't have to convert any points or anything, it all just works. Great! Now, the client also wants to ...
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1answer
220 views

Warping images with unknown projection

I have tried to used gdalwarp to project set of images(from hdf4 files to tif) before merging them using gdal_merge. But then the merge output has spaces/blanks. They're not merge properly, and I ...
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1answer
936 views

Transforming between epsg:3857 and Google Maps Tile coordinates

Hio, I used to use a simple python project (https://github.com/hrldcpr/mercator.py) to convert between wgs84 and google maps tile coordinates. This project doesn't have a license, and looks like it ...
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1answer
306 views

How to import and project ASTER 1B data into Arcmap?

I recently purchased a granule of ASTER 1B data from ERSDAC, when I import any of the associated rasters into ArcGIS, the image is displayed as being only 1m across, when the actual area represented ...
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2answers
914 views

How do I convert Geo-Coordinates to Pixel-Coordinates on a Map?

I have an image file that is a Robinson Projection Map of the world. I have a list of geo-coordinates. I would like to find the pixel-coordinates on the map that correspond to my the geo-coordinates I ...
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1answer
306 views

Projecting INEGI shapefiles from Mexico

I have two INEGI files from Mexico (1990 and 2010) that I want to use the same projection. The 2010 file works fine (see below) and I would like the 1990 file to match the 2010 one. The shapefiles are ...
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0answers
48 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 ...
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1answer
496 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 ...
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1answer
339 views

Difference between Geographic and Projected coordinate systems?

What is the difference between a geographic coordinate system and a projected coordinate system?
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2answers
373 views

No prj file output from qgis:reproject

I'm trying to reproject a vector layer using the 'qgis:reproject' algorithm in the processing/sextante module of QGIS, from Python. This kind of works, but the .prj and .qpj files created after ...
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0answers
351 views

Incorrect coordinates when reprojecting NAD27 to NAD83

I have some historic UTM coordinates as NAD27 (556787, 7169250) which I entered into a spreadsheet and have imported into QGIS. I assign them the projection Nad27 / UTM zone 12N (EPSG: 26712) I ...
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1answer
554 views

Long range Trilateration from 3 lat, long, range

I've been looking at the following solution to a similar problem Trilateration using 3 latitude and longitude points, and 3 distances However with my problem the 3 points are spread over a large ...
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1answer
3k views

How to transform World data from EPSG 4326 to EPSG 3857

I have tryed different opensource tools to transform a world data shapefile from 4326 to 3857 but I always have an error. Im not sure, but is it because of Antartica? I have tryed with GDAL and QGIS ...
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1answer
441 views

Pseudo Mercator error?

I'm mapping on QGIS, I have a vector layer and his CRS is on EPSG:4326 - WGS 84, but also I wanted to put a satellite image, so when I do it, the image use WGS 84 / Pseudo Mercator. The problem is, ...
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1answer
114 views

Setting coordinate systems in gvSIG: workflow or transformation issues

I am learning how to use gvSIG 1.10 (Mac OS 10.6.8 Snow Leopard). My goal is to create a simple county map of Illinois using the base data shapefiles available from the Illinois Natural Resources ...
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2answers
1k views

Why is Format of output data grayed out on Save As dialog for Rectify?

I started georeferencing and I could not save my new "rectify" file, I don't know if is because of the raster or I did something wrong. Then I find out that my control layer is not accurate, it ...
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1answer
270 views

QGIS Projections

I am new to the GIS world and have faired pretty well with ArcGIS 9.3, learned and still learning on the job. I would like to get a better handle on QGIS though. I linked the files from my dropbox. I ...
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1answer
688 views

How to calculate oblique photo scale?

Is it possible to calculate oblique photo scale by given vertical photo scale ? I mean is there any kind formula relation between them or maybe is it possible to calculate rough approximation of ...
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1answer
156 views

Get relative north aligned point 2163 (US Equal Area)

What I'm trying to do is create a grid where the y axis is north aligned. I have a origin Lat/Lon point which is the bottom left corner of the grid and each cell should be 100 by 100 meters. So I ...
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2answers
608 views

Setting projection of tif file in QGIS? [closed]

I get this error when trying to define a projection for a tif file in QGIS: ERROR 1: Too many points (3249 out of 3249) failed to transform, unable to compute output bounds. How do I work ...