Stack Overflow
Stack Overflow

Questions tagged [map-projections]

A map-projection transforms the coordinates of the spherical earth to a flat map in cartesian (x,y) space.

A map-projection transforms the coordinates of the spherical earth, usually given in degrees (latitude, longitude), to a flat cartesian (x,y) space.
There is no perfect projection, it can be proved that each projection has a drawback, one have minor others major ones.

448 questions
3
votes
1 answer

Changing shape file projection for visualisation with D3

I am trying to produce a visualisation involving a map of the UK and all of it's ~650 electoral constituencies. I have drawn the map by following this excellent tutorial http://bost.ocks.org/mike/map/ and it works great. However the only source I…
toby
  • 683
  • 2
  • 6
  • 16
3
votes
1 answer

Plotting topojson file with d3.js (NYC boroughs and census tracts)

here is the first topojson question on so. I am having problems rendering a map (NYC boroughs) and can't figure out why. The code below is just a copy of this example with a different topojson file. I have uploaded the file here. Below are also the…
user2503795
  • 4,035
  • 2
  • 34
  • 49
3
votes
1 answer

Translating LAT, LONG to actual Screen X,Y coordinates on a Equirectangular Map Projection in AS3

I am doing a little project on Geo Locations. I need to highlight certain cities on an a map that is in equirectangular projection. I have got the LON LAT values for those cities, I need to find a way to translate those values to actual x,y…
user1922841
2
votes
1 answer

vector projection in OpenLayers

I am building a GIS app in geoDjango with OpenLayers and using data from PostGIS in projection EPSG:3908. The base layer is OSM. When I add vector data I got it rendered near Brazil instead of Bosnia. I tried everything but just can't get the…
vladobl
  • 33
  • 5
2
votes
1 answer

OpenLayers EPSG900913->EPSG4326 conversion gives wrong results

I have a problem with converting pixel location from screen to degrees (EPSG4326). The lon/lat value in EPSG900913 is correct, according to http://proj4js.org/ and google maps. Some example values I'm getting are EPSG:900913 lon: 2763836.8383036,…
Marcus
  • 5,083
  • 3
  • 32
  • 39
2
votes
1 answer

How to correctly find UV on sphere

I have a sphere and a texture for it. Texture consist of 16 tiles of zoom = 2 from OSM. Tile size is 256x256. At top and bottom I added space to cover area in ranges [90, 85.0511] and [-85.0511, -90], proportionally. So texture size was…
Dmitry
  • 87
  • 1
  • 8
2
votes
1 answer

How to avoid connecting polygon vertices in the wrong direction when projecting a polygon?

I have a polygon that defines the boundaries of a study area. The area is quadrilateral. However, when I convert it from Lambert Conformal Conic projection to WGS84, one connection between two vertices is now drawn from west to east instead of from…
canderson156
  • 1,045
  • 10
  • 24
2
votes
1 answer

Piece together a projection using cartopy

I was trying to get a map projection using cartopy in python and it wasn't made so I'm trying to piece it together using to subplots with the following code: fig = plt.figure(figsize =(25,13),facecolor='white') gs =…
vgarza
  • 39
  • 1
2
votes
1 answer

Can I reverse xaxis in Aitoff projection supported by matplotlib? (It is not duplicate.)

I want to reverse my xaxis of my aitoff projection in my python script. Here is an example import numpy as np import matplotlib.pyplot as…
Kyle
  • 80
  • 4
2
votes
0 answers

Why do we use crs.PlateCarree() instead of crs.Geodetic() when using Matplotlib and Cartopy to plot a map based on lat and lon?

I've been learning how to use Cartopy and Matplotlib to plot map. But I have a question regarding the argument transform. According to the Cartopy document, transform specifies "what coordinate system your data are defined in". Suppose I am going to…
Yifeng
  • 21
  • 1
2
votes
1 answer

Visualize PostGIS geography bounding boxes to understand the "&&" operator

I have a point at (-130.2, 30.5) and a box at (-130, 30, -129, 31). As geometry, the && operator reports no bounding box intersection, while as geography, it does: WITH src(point, envelope) AS (SELECT ST_SetSRID(ST_MakePoint(-130.2, 30.5), 4326)…
sjones
  • 301
  • 4
  • 8
2
votes
1 answer

sf in r - one projection works, another throws an invalid geometry error

I'm trying to draw some maps with sf and ggplot2, and I'm having some odd behaviour. I was running the map before using the EPSG projection number 3310, and that worked fine: world <- st_read("world_map_path.shp") syear <-…
Sjiveru
  • 107
  • 6
2
votes
1 answer

D3 avoid projecting data that extends beyond the frame

I'm working on a D3 project that involves a large zoomable map. Everything looks good and works fine except that when I zoom and pan the view can get a little laggy. I'm wondering if D3 has a way for me to avoid projecting the map data that extends…
Jacob Philpott
  • 538
  • 1
  • 8
  • 24
2
votes
0 answers

Mapping a spherical cap onto a plane

I'm neither a geometry student or a native speaker, so apologies if my question isn't clear enough. As part of my master's thesis, I have to plot bounded regions of the night sky onto a 2D plane. My current solution consists of a rectangular mapping…
António Dias
  • 23
  • 4
2
votes
0 answers

Display Earth map in Azimuthal Equidistant Projection

I have to display the Earth's map in azimuthal equidistant projection, by giving the lattitude and longnitude as input in Matlab. I am using the eqdazim projection, but I am still getting the map with point (0,0) in the center. I want to be able to…
KS0232
  • 157
  • 2
  • 9
1 2 3
…
29 30