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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71 views

How to get geodetic area? rgeos::gArea doesn't seem to work. Or area-preserving projection

I need to get an area of different polygons at continental scale (like third of Africa etc.). Usual functions like rgeos::gArea work only in the projection units. Is there any function which works ...
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61 views

raster data and polyline shapefile do not line up

I am working on an ArcMap .mxd encompassing the state of new mexico. I have a shapefile of the state boundary with the following coordinate system GCS_North_American_1983 WKID: 4269 Authority: EPSG ...
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455 views

Converting from kilometers to degrees distances?

We have geometries in a Postgis database with SRID WGS84 and we have found lookups directly in degrees to be much faster than in kilometres, because the database can skip the projections I would ...
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32 views

Measuring different values in latlong Geotiff whether OTFR enabled or not

I'm using a GeoTiff file in QGis that has no projection per-se (it uses lat-long coordinates) and WGS84 datum. Further it has an x pixel size of 2.40475e-07 degrees and a y pixel size of ...
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33 views

Map Projection - Why don't we draw things out

I have been reading about different map projections and kind of understand where the problem lies. And also, most of the problem was that the old cartographers did not have any other tool other than ...
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73 views

How to choose a projection for area measurement on building to continental scales?

I have many geographical objects described as polylines, polygons, multipolygons. All objects are in WGS84. Object could be: a building, stadium, park, street, highway, city, state, even country and ...
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44 views

Atlas with different projections in QGIS

I have created an atlas -- i.e. a map with a layer defining some regions of interest -- in QGIS. I can render maps of each region using the "atlas" feature of the print composer, but I want to show ...
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53 views

MapInfo Point Object Dialogue is different to Info Tool's Transformed XY

A MapInfo Professional 11.0.3 user has re-projected data from AGD84 Zone 50 to WGS 84. However when they select a point and look at the point objects's X and Y, they are different to what's reported ...
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95 views

OTF reprojection and reprojecting layer not working in QGIS

more troubles in QGIS. I georeferenced this raster in Corrego Alegre UTM23S and loaded up, so project CRS automatically changed to that. So far so good. I need it to be however in WGS84 UTM 23S. None ...
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2answers
39 views

Is publishing geodata in unprojected latlon coordinates better than a local UTM projection?

This is meant as some kind of reference Q&A. Unless I am working with truly global data, I always prefer projected, local, metric coordinates so that calculations like area or distances are ...
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191 views

Is there a way to get undistorted maps in R (when using the OpenStreetMap package)?

When I download a large map within R (using the OpenStreetMap package) and I reproject the map (ideally to +proj=longlat), the map will always turn out distorted, making country labels etc. near the ...
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114 views

Defining the azimuthal equidistant projection of an Environment Canada weather radar map

Environment Canada helpfully provides recent captures of all national weather radar stations at http://dd.meteo.gc.ca/radar/PRECIPET/GIF/ at ten minute intervals. These are the same GIF images as ...
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105 views

Projection issues whilst opening shapefile in ArcMap created in QGIS

I created a polygon shapefile in QGIS. Projection was saved as EPSG: 3857, WGS 84 / Pseudo Mercator. When I open this shapefile in ArcMap the projection sets itself as WGS_84_World_Mercator which I ...
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36 views

Impossible to define the shapefile projection properly [duplicate]

I downloaded some dataset from Hot Export. By default they don't have any projection or coordinate system defined. The only thing I can see is the Feature Extent with values such as: Max Y ...
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205 views

Projection For Measuring Distances

Is it the case that when I use Arc GIS to compute nearest distance from a point to a poly-line/polygon, I need to project them both in an equidistant projection? Note: I am using the near tool. What ...
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114 views

After how much distance does the x,y coordinate system become noticeably distorted?

I'm working with maritime sensors that give information of moving objects it detects, in azimuth, range and elevation, and we convert it to x,y coordinates for our application to be able to process ...
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3answers
531 views

How to project a layer from WGS84 lat/long (automatic projection) to WGS 84 UTM Zone 23S in QGIS?

So I have a vector layer of polygons in WGS 84 lat/long (i.e. using the automatic projection for lat/long and WGS84 datum). I want to change that to WGS84 UTM 23S in QGIS. I tried doing like online ...
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95 views

Polyconic Projection for China?

I have a set of locations/points and I am trying to compute the nearest distance of these points from a Polyline. The points and the polyline lie in China and the Geographic Coordinate System is WGS ...
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158 views

How do I find/define a projection that gives me exact relative positions inside an area?

Assuming that a set of positions are all inside a 5km square area: How do I find/define a projection to reproject the positions, so that the relative positions between the now reprojected positions ...
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22 views

Problem with the DSID Data Set Identification

In my s57 file, I need to set the extent of the mapcanvas, for that i use : mpMapCanvas->setExtent(mpS57->mMapplay.value(DSID)->extent()); but if I display the value of the extents xmin, ...
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69 views

How to get correct lengths when switching from GCS to PCS?

I'm working on ArcMap 10 and need to get the lenghts (in meters) of the segments composing my line feature class. GCS of the line is WGS_1984. Extent of this data should be: Left 11.236520 dd, Right ...
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68 views

Is there a difference in results between Simplifying a geometry by different projections?

We have geometries in a PostGIS database projected in srid 4326. We need to have these geometries simplified with ST_SimplifyPreserveTopology. My question is whether this geometry needs to be ...
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1answer
84 views

Strange effect in gdalwarp output

I am using gdalwarp in python to extract and re-project reflectance bands from MODIS level 1B (MOD021km). An example of the command that I am using is the following: gdalwarp -of GTIFF -tps -t_srs ...
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57 views

Extracting *.tif agricultural area from shapefile?

I am attempting to extract from an image using Esri shapefile that is in the zip file RR_KZKD2012 In ArcGis the spatial reference is Projected Coordinate System: WGS_1984_UTM_Zone_43N. Then am using ...
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115 views

Feature Points Shapefile missing Spatial Reference Information

I'm working with ArcMap 10 and I have a feature points shapefile from the Florence (Italy) municipality open data (http://opendata.comune.fi.it/statistica_territorio/dataset_0040.html). Each point is ...
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148 views

Postgis geometry column with different srid

I have a table that has geometry column named the_geom. I set SRID value to 29903. And I used Openlayers api to view data on map. I set map srid as 29903 and works well. But if I need to show my data ...
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116 views

Using CAD data that is not to be projected in ArcMap?

I need to incorporate CAD data into my geodatabase but the usual steps seem to require defining a projection or projecting the data in some way. All of my geodatabase's feature classes are in ...
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1answer
412 views

How to access Leaflet EPSG:3857 coordinates?

I read everywhere that Leaflet is internally using a spherical web mercator (EPSG:3857), but whatever I try I get either Lat/Lon (EPSG:4326) or strange coordinates I dont understand: ...
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41 views

NetCDF4 Files: Missing Projection & Varying Dimensions (Multiple Files)

All, I hope you can shed some light on issues I've been having regarding NCEP Reanalysis-I netCDF-4 file format: First issue, Projection information is not stored on the downloads I obtained from ...
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250 views

Layers with the same CRS in QGIS do not line up

I am busy with a project where I have to layer a .dxf and a .kml file but the layers are not lining up. The .dxf file's coordinates are completely wrong and the scale also does not appear to math up ...
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38 views

Aligning Points in Decimal Degrees

Running ArcMap 10.3 I am displaying a layer of manholes from a table coming from SQL. The XYs are in decimal degrees however they are displaying no where near my other layers (NYC PLUTO). I have ...
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108 views

Working with lidar points (LAS To Multipoint) in ArcGIS for Desktop?

Currently I'm working with the LAS format and want to transform from WGS84 to RSO Kertau Malaysia. I'm using ArcGIS-Las to Multipoint and Data Management Tool-Project and succeeded in the ...
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662 views

What is/are the coordinate systems used in South Africa?

What are the principal datums and projections used in South Africa including the names of geodetic datums and their projections?
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78 views

Projected MODIS data not aligning with ESRI basemap in ArcGIS for Desktop?

I can not get 1km MODIS data aligned with ESRI basemaps in ArcGIS 10.2.2 for Desktop. See the photo below. I reprojected MODIS17A3 data using the MRT (MODIS reprojection tool). I selected WGS84 ...
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299 views

Proper ground-to-grid correction and projection from old survey maps

I asked this question over on the ESRI geonet site, but haven't had any luck there, sorry for the duplication... I'm working on digitizing a group of maps from the 1950's that show locations of ...
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14 views

Vector data getting misaligned in final print in QGIS [duplicate]

My printcomposer view shows the data correctly aligned with background OSM/Google/Bing data but the final print makes it all misaligned. Data is in 3857 What can I do?
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185 views

GeoJSON and OSM layers with different projection

I have a GeoJSON from NaturalEarth for world state boundaries and I want to display it with only without backgroung. But also, I want to add a OSM layer as another baselayer option. The code I am ...
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65 views

Projections way off on data imported into QGIS?

I have elevation data as a .shp from the USDA ARS and Hi-Res Orthoimages (Mystery Projection (UTM 15N?)) from the USGS website as geoTIFFs (plain NAD 83). I am trying to project all of the images ...
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97 views

Which projection can I use to see alignments on great circles?

I want to put on a QGIS map some historical sites to check if they are aligned. If an alignement exists, the points should stay on a great circle (is this correct?). I want to visually verify this ...
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37 views

Generating Scale Bar for Raster Image Data

My goal is to create a scale bar for a printed map at 1:1,000,000 scale. The input dataset is a Mercator projected geotiff. Using GDAL it is possible to get the spatial reference information and ...
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48 views

Why can I publish a layer in Geoserver using these two different projections?

I have a shapefile with this projection in the .prj file GEOGCS["GCS_WGS_1984", DATUM["D_WGS_1984", SPHEROID["WGS_1984",6378137.0,298.257223563]], PRIMEM["Greenwich",0.0], ...
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53 views

Troubles setting correct projection in SDE

I have to transformate data and change the coordinate system but have troubles to set it correct programmatically. I have: ArcGIS 10.2 / MS SQL-Server 10.0.5520 / sde 10.2.2 My steps: 1) Some ...
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1answer
518 views

What simple and light Java library to use for WGS84 to UTM conversion?

Geotools and Geotoolkit are huge and complicated. CTS (1.3.3 from Maven) failed on me by not even being able to run its own test example (slightly modified ...
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1answer
364 views

Get Radius in epsg 4326 with Openlayers 3

What is the best method for getting the radius of a circle in Openlayers 3 in epsg 4326 (geodesic)? I'm using this example for a base and trying to draw a circle while getting the radius, but using ...
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2answers
29 views

Selecting the correct projection for NAD_1983_HARN_WISCRS_Bayfield_County_Feet

I am trying to map the following projection but having issues finding a one that works. I ahve used http://prj2epsg.org/search which gives a few results but none seem to work that well. ...
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57 views

What would a map of the world look like if lat/longs were treated as projected coordinates? [duplicate]

I'm not quite sure if I'm phrasing this right. It's just occurred to me that lat/longs are two dimensional coordinates like any other projected coordinate system, so it's presumably possible to create ...
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114 views

Equal Area Projection for Indonesia - Standard Parallels

I am trying to do area computation stuff over whole of Indonesia and as such, am using the following projection: http://spatialreference.org/ref/esri/asia-south-albers-equal-area-conic/ To make this ...
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68 views

What projection to use for many parts of the world

I'm creating a poster which has many separate maps (rivers of the world). I'd like to use a similar projection for each of them, so they're comparable in terms of shape and size. I guess I want some ...
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1answer
114 views

Reproject GEOTIFF tiles from UTM to Plate Caree

I need to reproject several GEOTIFF tiles(each having different height/width) in six different UTM zones from UTM to Plate Carree. Output of gdalinfo of two sample tiles is enclosed. As is clearly ...
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49 views

projection for high accuracy small areas

I need to convert (lat,long,height)points into a cartesian system for an area as small as 40kmx40km or even 10kmx10km. I'm currently using the UTM projection, but there are some issues regarding ...