Tagged Questions

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

learn more… | top users | synonyms (1)

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1answer
51 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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0answers
49 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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0answers
31 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
160 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
79 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
69 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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0answers
67 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
45 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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0answers
62 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
47 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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0answers
57 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
86 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
30 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
votes
1answer
141 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
42 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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0answers
36 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
93 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
142 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
55 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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0answers
53 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. ...
1
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1answer
30 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 ...
1
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1answer
60 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 ...
1
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1answer
75 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
96 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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0answers
33 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? ...
6
votes
2answers
100 views

Why has an orthographic projection been used in this NatGeo map?

I'm wondering why this maps uses an orthographic projection, resulting in 3 maps to view the whole world. What were the requirements or the reasons to choose this projection (why not Mercator ) ? ...
0
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1answer
41 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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0answers
37 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" ...
1
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2answers
155 views

Wherer is wrong with transforming a WGS84 [lon,lat] point onto google maps

I want to convert a longitude latitude point in WGS84 coordinate system to Google Maps(not google earth) coordinate, But when I put the converted point on google map, it always has a roughly 10km ...
0
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2answers
52 views

OpenLayers + Geoserver problem with wfs projection

In geoserver i have a layer in EPSG:26191. In OpenLayers i add it on map as WFS: markerLayer = new OpenLayers.Layer.Vector('Markers',{ strategies: [new OpenLayers.Strategy.Fixed()], ...
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1answer
52 views

which Coordinate system should I use for 3D analysis?

I am creating 3D surface below the earth's surface using ArcGIS and then I need to find distances to the plane from the surface. Which coordinate system shall I use? 3D interfaces like IProximity3D ...
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0answers
53 views

Why can't I reproject from HARN State Plane Ft Intl to State Plane Ft?

I'm attempting to reproject a feature class that is: NAD_1983_HARN_StatePlane_Oregon_North_FIPS_3601_Feet_Intl to our standard, which is: NAD_1983_StatePlane_Oregon_North_FIPS_3601_Feet When I ...
1
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2answers
71 views

Projection for polygon intersection confined into one hemisphere?

I have polygons where each vertex is a (lon,lat) geographic coordinate. I want to find out if they intersect or contain each other. The polygons are guaranteed to never exceed a hemisphere (so they'll ...
1
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0answers
32 views

Geodjango transform introduces large errors

Apologies for the possibly naive question. I'm trying to understand how Geodjango (running on PostGIS) deals with coordinate transformations, and am experiencing some unusual behaviour. Let's say I ...
2
votes
1answer
47 views

Geoserver projection recognize problem

I'm publishing shape files in geoserver through curl,my problem is that geoserver didn't recognizing the projection which is in ESRI WKT format(layer was publishing).I searched for this problem i ...
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0answers
139 views

Fixing Mapinfo export to Google Earth projection which is slightly off?

I have around 20 layers of data (points and polylines) in Mapinfo TAB files which I need to export to KML files, however the projection is slightly out. I have tried various different projection ...
4
votes
1answer
102 views

What's the correct way to reproject a population raster?

I'm working with a population raster that is in the WGS84 coordinate system, and I want to get it into a projected coordinate system (Albers Equal Area), using ArcGIS 10.1. According to the metadata, ...
1
vote
1answer
232 views

Is there a standard projection for Sub-Saharan Africa?

With the help of d3.js, TopoJSON, and data from Glottolog I have made this map of Bantu languages that exist in Sub-Saharan Africa. I've used the standard Mercator projection so far. I know that ...
2
votes
3answers
108 views

Problem with Geometry SRID in PostGIS

I ceated my table (borne) in PostGIS id_borne serial NOT NULL, num_borne character varying, shape_borne geometry I successfully changed the SRID of my table using select ...
0
votes
1answer
76 views

QGIS to solve projection mystery in Postgresql

I downloaded some data from local agency. Per QGIS 2.2, I defined the projection to 'EPSG:3587 - NAD83(NSRS2007) / Michigan Central' in postgresql (maybe ArcMap). Data is in Postgresql 9.3. I am ...
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2answers
67 views

Accurate local map projections

Is there a map projection that can accurately represent reality at a local area, i.e. when transforming the map could I choose an area that I care about accuracy and allow distortions elsewhere? Like ...
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0answers
104 views

MySQL+GDal+MapServer+OpenLayers WebMercator problem

I have a problem/question what is the most efficiant way to go from WGS84 (epsg:4326) to webmercator. Outline of the structure right now: MySQL Database: with point Latitude/Lontiude Data [~200 ...
3
votes
2answers
51 views

Choosing projection to use for Least-Cost Path analysis at continental scale?

I am trying to find least cost paths from the southern USA to the Great Lakes region (for example). My resistance layers are currently in an equal area projection but I'm wondering if I should convert ...
1
vote
1answer
77 views

Correcting coordinates of CAD drawing imported into ArcGIS?

I am having some issues with some CAD drawings that I have imported to ArcGIS. I have a number of CAD drawings where by the features within the drawing have an error in their coordinates. For example, ...
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0answers
95 views

Conversion problem of projection of MODIS LAI from sinusoidal to geographic

I am trying to change MODIS data's (LAI) sinusoidal projection to geographic. Actually I did it. But when I reproject it by ERDAS, the output LAI raster moved about 10 km to west side of actual shape ...
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0answers
25 views

EPSG1612 transformation [closed]

I have survey data for contacts listed as eastings and northings - I need to overlay this onto PNG files but the location is quite far north - How do I apply EPSG 1612 transformation to the UTM Zone ...
0
votes
2answers
131 views

projection conversion from mercator to google maps format

Is this spTransform(Finland3, CRS("+proj=longlat +ellps=WGS84 +no_defs+ellps=WGS84 +towgs84=0,0,0 ")) the right way to project a shapefile with this projection coord. ref. : +proj=merc +lon_0=0 ...
0
votes
1answer
35 views

Projections when using google maps and rest service on openlayers

I am trying to use a rest service on an openlayers map that has 2 google maps layers. The google map layer is set to it's own custom projection (which I had to code into the library by hand, but I ...
0
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0answers
86 views

Creating a custom Lambert Conformal Conic projection in ArcGIS 10.1 and/or 10.2.2

referring to the table below, I am trying to use the values on the left from another program that uses different terms for the parameters of a custom projection. I just wanted to make sure that ...