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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How to overlay a flat image onto google maps with two points of reference?

The Android API allows for images to be superimposed onto a map. To do so, the developer specifies a set of lat/long coordinates for an "anchor point" within the image, the width (or height) of the ...
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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, ...
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35 views

QGIS doesn't create the correct projections when creating new shp files

I received shapefiles exported from ArcGIS with EPSG:2227 as the CRS, which should be: +proj=lcc +lat_1=38.43333333333333 +lat_2=37.06666666666667 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000.0001016 ...
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How do ESRI and QGIS calculate scale values of geographic projections?

Does anyone know how (from which location) scale values are calculated in ESRI products and QGIS for geographic projections? The only thing I've noticed is that QGIS is changing scales when you pan ...
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1answer
30 views

Reprojected Shapefile does not align with Openlayers Plugin

I am based in NSW, Australia. I have a shapefile that when I underlay with the openlayer plugin (google satellite), the shapefile is skewed despite all my efforts to correct it. I changed the ...
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18 views

Striping Artifact in Aster DEM Mosaic

I'm working with SRTM and ASTER data for a university project. My goal is to delineate watersheds and evaluation of these with ArcGis 10 and ArcHydro. But a striping error occurs with the flow ...
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1answer
49 views

Change projections depending on the zoom level

Is it possible in ArcGis (from a technology/performance/… point of view) to switch projections depending on the zoom level? For example, Is it possible when zooming at some extent to the poles, my ...
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1answer
33 views

Crop and reproject shapefile based on GeoTIFF sample

I have GeoTIFF with these attributes: Size is 495, 309 Coordinate System is: PROJCS["unnamed", GEOGCS["unnamed ellipse", DATUM["unknown", SPHEROID["unnamed",6370000,0]], ...
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1answer
24 views

Issue with gdal getprojection and setprojection returning different information

I am using Landsat imagery from the USGS. Those who use them may know that the projection attribute is wrong (everything is in the Northern hemisphere). I have a script to process tar.gz files and ...
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1answer
29 views

Equal Area Projection for Central Ethiopia (37N)

Can anybody please tell me what is the best equal area projection for central highlands of Ethiopia. I am assuming Albers Equal Area Projection. Any suggestions?
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2answers
46 views

Projected coordinate system for South America

Does anybody have any suggestions for a projected coordinate system for the Northern part of South America? I have a data set that reaches from Venezuela to Southern Peru and I'd like to do some ...
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1answer
51 views

Identifying projection for shapefile with unknown coordinate system, no z values and no measures? [duplicate]

I am attempting to create a GIS Project with multiple Brazilian cities. I have been collecting, and am interested in, shapefiles that delineate the neighborhood boundaries of said cities. One city's ...
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1answer
24 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 ...
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12 views

How to generate map tiles with TileStache and a custom projection

I would like to generate my own map tiles using TileStache and a custom projection. I have been struggling with this for quite some time and am hoping I can get some advice to get the tiles to ...
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209 views
+250

A global, grid-like projection for creating heatmaps

I'm putting together an application where I need to create a vector grid which will be used to store and display a heatmap. It has the following requirements: Can cover the entire planet. The vast ...
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26 views

How do you clip a gnomonic or stereographic azimuthal projection?

I have polygons comprised of lat/lon coordinates and I want to project them onto a plane that's appropriate for polygon operations (such as checking for intersections). In some cases, the polygons ...
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2answers
47 views

Help projecting Austria data with QGIS

I'm trying to reproject this dataset from Austria Statistik Geodata. Data comes in "MGI_Austria_Lambert", and I'm trying to reproject to WGS84 What I'm doing is Saving layer as... and selecting ...
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1answer
69 views

Changing map projection and adding graphic features in projected coordinate system using ArcGIS API for JavaScript?

I'm having some problems with the ArcGIS API for JavaScript. I have a web service that traces an electric network and sends back JSON with point and polyline (path) geometry. I've created a function ...
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44 views

ArcGIS WGS84 Web Mercator Vs. WGS84 UTM zone 15N: Very different distance dimensions

I am working in ArgGIS 10.1 with a field (raster layer in tif format) in which I have placed two points (.shp layer). I have two versions of both layers, resulting four layers: one tif+shp set in CRS ...
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1answer
64 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 ...
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2answers
74 views

Google layers not matching

I'm working in a project with whole Europe data. I'm working with WGS84 (4326), and sometimes I overlay my polygons with Google maps layer (in QGIS) to see some details. When I do this, I have to ...
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1answer
31 views

Unable to save to in Geojson format with the correct projection

I have a shape file (Polygon) in Qgis that I wish to save in Geojson in order to display it with the mapbox javascript api. Original projection is in POSGAR 97 My issue is that it does not reproject ...
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25 views

Arcmap: transform an image from Web Mercator Projection to Simple Cylindrical (Plate Carree) projection

I have an image that is projected using the Web Mercator projection. Does anybody know how to transform (in Arcmap) this image from the Web Mercator projection to the Simple Cylindrical (Plate Carree) ...
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29 views

Vector seems to be only a pixel of a raster after reprojection

I have the South America hydro1k data for slopes and I am trying to extract the data using point sampling tool with a grid in Brazil's map. My problem is that, even though vector and raster seem to ...
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2answers
67 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
22 views

6 degree to 3 degree Transverse Mercator transformation

I am looking to plot coordinates that were given to me but I am having some issues projections. I currently have my data projected to NAD83 MTM 1, but the coordinates that were given to me are based ...
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1answer
47 views

Shapefile not projecting correctly [duplicate]

I am still new to this, so I apologise if I don't make a lot of sense! I am using QGIS 2.4.0 Chugiak. I am working on a project set to the GDA94/MGA Zone 50 coordinate system with 'on the fly ...
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41 views

Difference between feature to raster and polygon to raster

(I'm using Arc 10.1) I'm trying to rasterize a data set. I have a shapefile with geographic coordinates (GCS_GDA_1994) which I want to convert to a raster with 100m grid cells. So I need to project ...
2
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1answer
27 views

Error reading large virtual raster with rasterio: “Cannot invert degenerate transform”

I've created a virtual raster using gdalbuildvrt, which covers a large extent (England) at a high resolution. The data is fairly sparse, focused around the coastlines with no files covering inland ...
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40 views

Google Map Projection Skew - Need correct Projection

I'm having a really difficult time resolving skewed grids when projecting onto Google maps using Alteryx outputs. Within the module, I'm taking GRD files and aggregating rows and columns to re-size ...
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1answer
26 views

Projecting INEGI shapefiles from Mexico - not lining up [duplicate]

I have two INEGI shapefiles from Mexico (2000 and 2010) that I want to line up with one another. The 2010 file projects in the right location and I would like the 2000 file to match/line up with the ...
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40 views

Understanding X Y coordinates: geocode before or after projecting? What determines how many decimal places?

I am trying to figure out how different my groups' past Network Analyst analyses have been because they were using a geographic instead of projected coordinate system. But I'm getting hung up on the X ...
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1answer
52 views

Why is this .prj file causing the shapefile to render in meters instead degrees?

So I've got a shapefile that has polygons of countries, with coordinates in decimal degrees: Country (String) = Algeria POLYGON ((6.928073999999953 36.88360652, 6.949973999999969 ...
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1answer
21 views

Figuring out what coordinates supposedly using 'NAD31 projection' refer to

I'm working with a GeoJSON file that contains sets of coordinates associated with street corners in the city of Montreal, Canada. The spec sheet of the API delivering those GeoJSON specifies that the ...
2
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1answer
125 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 ...
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1answer
31 views

Determining projection of Texas county shapefile?

I have a Shapefile of San Jacinto County in Texas. It thinks it is NAD83 UTM Zone 15N, but the dataset isn't jiving with any other dataset. Max X: 1,073,721 Max Y: 11,223,970 Min X: 895,728 ...
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21 views

Question about projected coordinate systems 30m DEM for Contiguous US

What is the best Projected Coordinate System (PCS) for the contiguous US (whole, not parts) if I want to maintain distance and area accuracy as much as possible across a nationwide DEM dataset? I'm ...
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1answer
66 views

Defining projection, reprojecting, and wrong area values [duplicate]

Apologies for duplication--this was mentioned in a previous post, but was suggested that this specific problem should be posted separately. My data: http://water.usgs.gov/GIS/dsdl/aquifrp025.tar.gz ...
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1answer
115 views

What are the pros and cons of forcing square pixels on reprojection?

I am using Erdas Imagine 2014 to reproject 4-band raster data from GRS 1980 NAD83 Lambert Conformal Conic (ft) to UTM GRS 1980 NAD83 North UTM Zone 11 (m). Unlike ArcGIS, Erdas provides the option to ...
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1answer
51 views

Cannot obtain correct area values *With* correct projections

I'm trying to get the percentage of each U.S. county overlaying groundwater (data from the census and USGS respectively). They're both polygons. I have 1) correctly projected the data and the layer ...
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38 views

Is it possible to rotate the geographic projection in QGIS?

I'm trying to create a Qgis plugin that can rotate a raster layer in the canvas so that the north is pointing at another direction. Unlike the thread below, I'm open to defining a custom projection. ...
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1answer
20 views

XY data --> NAD_1983_2011_California_Teale_Albers always fails?

In ArcGIS 10.2, I am importing XY (point) data from excel, and have been having trouble projecting it into the following Projected Coordinate System: NAD_1983_2011_California_Teale_Albers -- NAD ...
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1answer
47 views

image rectification with Mercator projection

I have written an image rectification function which allows a user to select 2 points on an image and 2 points on a map. The function will then rectify the image so it is translated, scaled and ...
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1answer
49 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 ...
3
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1answer
60 views

Projection mismatch when plotting precipitation with ggplot

I'm trying to plot accumulated precipitation in Brazil for a given period, see code below: Load packages library(raincpc) library(SDMTools) library(raster) library(ggplot2) library(rgdal) ...
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1answer
24 views

Custom projection with mapnik

I would like to superimpose openstreetmap data over a raster image, using mapnik. My problem is that this image is not in a projection being defined by a SRS, I have some non-linear algorithm to run ...
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31 views

What projected coordinate system to use for whole of USA? [duplicate]

I need to determine a projected coordinate system for a wide area that exceeds more than one zone? For Example: If I want to give US a UTM projection which zone will be represent the whole US? ...
3
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2answers
56 views

Why orthographic projection has been used in this NatGeo map

I'm wondering why this maps uses orthographic projection, and result is 3 maps to view the whole world, what were the requirments or the reasons to choose this projection (why not mercator ) ? this ...
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1answer
33 views

Drawn figure looks stretched

I have written some code which offset a certain latitude and longitude with a distance in centimeters. What I am trying to do is based on a coordinate and a vector create two new points along the line ...
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27 views

Euclidean Distance Function performed on unprojected data

I am looking to perform a simple multi-criteria analysis on a data set comprised of two criterion: occurence of wildfires and road accessibility. First, the project CRS was enabled with "on the fly" ...