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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12
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1answer
10k views

What is the default projection in Leaflet?

I've read an API documentation for Leaflet on its site, but I can't realize: what is a default projection to view maps? It was written about spherical and elliptical Mercator and Equirectangular - so ...
2
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0answers
15 views

Eliminating/minimizing distortion in 200 NM EEZ buffers [duplicate]

I frequently need to calculate buffers of 200 nautical miles from country or baseline polygons in order to map maritime Exclusive Economic Zones (EEZs). However, I've noticed that when generating the ...
1
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0answers
779 views

Lines as Great circles on a map

How can I get line features to appear as great circles on a map, instead of straight lines? Thanks,
2
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2answers
246 views

Problems with transformations in ArcMap

I have files projected in British National Grid. After I have transformed them into WGS_1984. I noticed that if I were to transform them back to BNG the original would not match the new. Is there a ...
2
votes
2answers
142 views

Measure areas, lenghts in specific regions (Australia, Sout East Asia)

I'm in need to find a suitable projections to measure correctly areas and lenghts for 2 areas of interest. I want to measure both factors for: 1) First region Australia & New Zealand (1st region)...
1
vote
1answer
599 views

Change coordinate system using SQL or Javascript

Is there any built in function in SQL Server 2008 R2 which can transform the cordinates from 102100 to 4269 coordinate system something equivalent to ST_Transform from postgres. If there is algorithm ...
6
votes
3answers
826 views

How can I obtain the same area values provided by the Census for TIGER boundaries using PostGIS functions?

In PostGIS, how can I compute the area of Census Boundaries and obtain the same results as are provided by the Census? For example, most Census Boundaries include attributes for Land Area and Water ...
2
votes
1answer
266 views

How can I transform Real-time Local position system coordinates into GPS/WGS84?

I have a local coordinate system built with Ubisense sensors and tags (it is a real-time locating system used to automatically identify and track the location of objects or people). The local ...
4
votes
1answer
136 views

How to select projection

I have to compare geometries anywhere in the world; mainly between 65N and 40S but also in the Arctic latitudes. I need "commercial accuracy" - not military or navigational. For example does a line ...
5
votes
1answer
871 views

Why is tiff different in epsg 3857 and epsg 900913 in gdal

When I transform tiff from 4326 to 3857 and from 4326 to 900913 in gdal, I get different result(when display in Qgis) eventhough these two projections(3857 and 900913) should be the same. What is ...
1
vote
1answer
59 views

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum by cs2cs?

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum (which uses locally defined geoid and height) by cs2cs? What I mean is that, by using cs2cs, ...
2
votes
1answer
144 views

Identifying coordinate system for Jersey

I'm trying to plot some X,Y coordinates which should be located on Jersey (the British dependency, not the state). The metadata that came with the points is as follows: Coordinate System: ...
0
votes
2answers
286 views

Shp's will NOT line up (coordsys) - shps made using GPSeismic sotftware (client made shp's)

OK, I asked this previously but solved it on my own last time. Same project, but differant shp files. I recieved from a client shp files that were made in GPSeismic 2011. Upon recieving the shp ...
3
votes
1answer
276 views

Convert planar distance to ellipsoid (real) distance

I have the following linestring which approximately marks an airport runway: LINESTRING(-381578.819887 6574044.360475, -378513.534443 6574799.475787) # EPSG 3857 LINESTRING(-3.427781 50.732117, -3....
2
votes
1answer
183 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 ...
4
votes
2answers
157 views

Why is it not advisable to perform spatial analysis on layers with source datasets having same datum but different projections?

I have read that it is not advisable to perform spatial analysis on two layers with source datasets having the same datum but different projections loaded in ArcMap. Since the second layer should ...
2
votes
1answer
160 views

Aligning layers with questionable metadata in SW Ontario

After making my best efforts to read/try everything I can on this forum and elsewhere, I unfortunately have to contribute to the wide literature of "my layers aren't aligning" questions. I am working ...
3
votes
1answer
590 views

QGIS not interpreting Lambert Conformal Conic projection correctly

I'm a fairly new user of QGIS and I've run into an issue that I can't seem to solve on my own. I'm trying to work with the NRCan Atlas of Canada Waterbodies SHP file but I'm having an issues re-...
1
vote
1answer
2k views

Pseudo-Mercator projection with Decimal Degrees?

Hope this isn't a duplicate, did some searching but none seemed quite the same. Projection I want: WGS84/Pseudo-mercator. Selected. Looks Great. Canvas units I want: Decimal Degress. Selected. ...
11
votes
2answers
2k 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 ...
1
vote
1answer
1k views

Reprojecting coordinates and geoJSON in leaflet

I have a Leaflet map in default projection and a wms layer also in default (web mercator) projection. I would like to add polylines and a geoJSON layer to my map, but the coordinates are in EPSG4326. ...
0
votes
1answer
148 views

how to correct merge rasters with different projections? [closed]

how to merge rasters with different projections with correct transforn? For example EPSG:32636 and EPSG:32637 if i do it with gdal_retile command, i have correct view for EPSG:32637 rasters and ...
1
vote
1answer
597 views

get data from WFS and present in using d3js - correct projection

I'm trying to get data for map of Poland. I found WFS service that provides GML files. It is located under: http://sdi.geoportal.gov.pl/wfs_prg/wfservice.aspx?request=getCapabilities&service=wfs I'...
2
votes
3answers
1k views

How to calculate Polyline length in kilometres without changing projection from WGS84 (using ArcObjects)?

I have Road (polyline) feature class and I wish to find those roads whose length are greater than 500 kilometre. The feature class projection is in GCS_WGS_1984 and I do not want to change the ...
2
votes
1answer
260 views

Axis of rendered shape files not showing numbers that are latitude and longitude

I am using rgdal to render some shape file. The first is a set of building zones from NYC Open Data. The second is the NYC coast line from OSM. The Zone files seems to generally render an X axis ...
3
votes
2answers
214 views

Convert data to another Coordinate Reference System

Assuming I've a point like this : POINT (751318 9760879) This point is in EPSG:27700 coordinate reference system. How do I convert the point to display in a map with EPSG3857 coordinate ...
6
votes
1answer
519 views

How do I change an existing srs in QGis?

I am showing postgis data with srid 28992 (Amersfoort / RD New). But when I plot the geospatial data on a map (with openlayers plugin), the data is shown a hunderd meters off because the datum shift ...
0
votes
0answers
874 views

gdal python set projection of a raster - does not work

Gdal 1.9.2, ECW driver: ECW/ERDAS Compressed Wavelets (SDK 3.x) I am having problems with the script that supposed to set projection of the ECW to EPSG:27700, i.e. the British_National_Grid. Please ...
-1
votes
1answer
495 views

How to project geographic coordinates to cartesian with the least possible error? [closed]

I need to convert geographic coordinates (in decimal degrees) to cartesian with the least possible error? I searched a lot on the internet but it seems that the conversion is not exact. Could you ...
5
votes
1answer
1k views

Manipulating Azimuthal Equidistant Projections in QGIS

I have a shapefile of world countries that is projected as Azimuthal Equidistant with Chicago, USA as the center. I would like to change the projection such that Edinburgh, UK is the center. One would ...
2
votes
2answers
8k views

how to convert latitude, longitude projection from epsg:3857 to epsg:4326

I want to use geocode in our application. so that, I got Google geocoding API and could achieve with Google Maps. Problem is that I wanted to achieve the same with my own map which is having ...
1
vote
1answer
538 views

How to Extract Data from U.S. National Landcover Dataset (NLCD) dataset?

I am working with U.S. National Landcover Dataset (NLCD) to classify habitat type at more than 150 sites across the northeast U.S. The dataset is very large (15GB) so I cannot upload it here, but it ...
0
votes
0answers
384 views

Lambert conformal conic projection - Europa

I am trying to calculate map of Europa in Lambert projection. I am using formula from wikipedia (Lambert wiki), but calculation is verřy slow with comparison to Mercator. I know, there are sin, cos, ...
8
votes
2answers
445 views

Should point data be equidistant projected when using ArcGIS IDW spatial interpolation?

I am wondering if anyone can clarify whether point data should be projected to an equidistant projection when using ArcGIS IDW spatial interpolation? I am working on a dataset from Western North ...
10
votes
2answers
1k views

Waterman butterfly projection in Mapnik

Like the title says, how would someone configure Mapnik to use the Waterman butterfly projection ? Otherwise, what other tools would be able to render using this projection ?
20
votes
5answers
2k views

Simplifying geometries (generalization)

What are the recommended ways of simplifying geometries? Keeping in mind projections, and simplifying state geometries for example. I've heard about converting to an 'equi-distant' projection that ...
2
votes
1answer
297 views

How to synchronize the marker's rotation field with the angular distortion in the map projection

I'm Using QGIS 1.8.0 to plot a global dataset showing the positions of aircraft in flight. The data I have are .csv files with three columns: Latitude, Longitude, and angle of travel. I assign ...
9
votes
1answer
800 views

An example Tissot ellipse for an Equirectangular Projection?

I am trying to calculate distortion of an equirectangular projection via Tissot indicatrices. I have tried following the directions on this post (among other things) but it is beyond my understanding ...
7
votes
1answer
3k views

Leaflet and EPSG 4326 Projections

UPDATE: LEAFLET fixed support for EPSG 4326 (LL84) in the latest betas: https://github.com/Leaflet/Leaflet/issues/1207 Leaflet says it supports EPSG 4326 (Plate Carree, aka ll84) projections. I think ...
4
votes
1answer
657 views

How to convert WGS84 to UTM when the study area covers 4 UTM Zones: 43- 46?

I'm working in ARCGIS 10.2, my area of interest falls in 4 UTM zones 43,44,45,46 equally distributed so i can't use the option of majority of area's UTM zone. Since i need to carryout varies analysis ...
5
votes
2answers
1k views

How do I specify a CRS for a fictional game map in QGIS?

I am about to start playing a steampunk RPG game called The Iron Realm, which uses a fictional world map. I have recently started using QGIS v1.7 and have no real experience with GIS sysstems. I have ...
4
votes
1answer
3k views

R - Plotting shapefile with geographical (raster) data

Over the last few days I have been trying to plot a shapefile over data loaded into a data.frame within R. It should be a view of radar precipitation with an overlay of the country borders from a ...
2
votes
2answers
464 views

Spatial Join of 2 line layers offset by minuscule amount

Let's say I have 2 line layers (green & red, in the image below) and I need to transfer attributes from one layer (red) to another (green) by doing a Spatial Join. The layers are identical, but ...
4
votes
2answers
163 views

towgs Definition for European Datum 1950

I am new to all things GIS so apologies for a basic questions. I am trying to specify the CRS of a climatic raster layer in R. It is an equal area projection based on Europe Equidistant Conic and the ...
3
votes
2answers
397 views

in python, srs.ExportToProj4() returns an empty string, why?

I have a shapefile with the following .prj file: PROJCS["NAD_1927_Albers",GEOGCS["GCS_North_American_1927",DATUM["D_North_American_1927",SPHEROID["Clarke_1866",6378206.4,294.9786982]],PRIMEM["...
2
votes
2answers
405 views

Plotting a certain range in azimuthal projection using ggplot2

I would like to limit a map to a particular range of values (i.e. northern hemisphere) under an azimuthal or orthographic projection in ggplot2. When I set ylim, I receive an error message that ...
1
vote
1answer
410 views

Problem changing CRS to enable clip function

I have two layers, one point file and one polygon. The point file is in WGS 84 and polygon in NAD83-UTM10. The project CRS is NAD83-UTM10. They project fine with on-the-fly projection turned on. I ...
-1
votes
1answer
650 views

My wms vector data overlay on openlayer vmap work fine but on osm img is not rendering

i am try to overlay my India roads vector over an openlayer (http://vmap0.tiles.osgeo.org/wms/vmap0) vmap work fine.but i want to do the sam task over osm(open street map), i am trying many different ...
3
votes
2answers
851 views

Variation of algorithms to find point from another point with bearing and distance

There are several algorithms to calculate distance between two latitude/longitude points. Haversine Hubeny Lambert-Andoyer Vincenty's formulae for inverse problem But there are not so many ...
1
vote
2answers
355 views

Coordinates values change for ArcGIS

I have received thousands of location information like below. X= 10°52.579 Y= 078°38.473 I don't have idea in which format is this, please let me know what is the format of this location and ...