Questions tagged [mercator]
The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569.
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Formula for calculating the local point scale factor of a secant Mercator projection with Autochart
I am looking at a projected coordinate system with the following parameters:
Datum WGS-84
Spheroid WGS-84
Semi-Major Axis (a) 6 378 137.000 m
Inverse Flattening (1/f) 298.2572235634
Latitude of ...
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Satellites GOES16 and 17 - reprojection to Mercator is stretched
I have downloaded GEOS data from https://cdn.star.nesdis.noaa.gov/GOES16/ABI/FD/ (or https://cdn.star.nesdis.noaa.gov/GOES17/ABI/FD/). I want to reproject the disk to Mercator projection. I have used ...
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148 views
Transform equirectangular simple TIFF to Mercator projection with gdal_translate / gdalwarp
I'm trying to transform this shaded map of Venus, a 2000x1000 TIFF in what I believe is equirectangular projection, without GIS metadata, to Mercator.
I first tried
gdalwarp -s_srs EPSG:4326 -t_srs ...
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46 views
Distance difference when moving longitude in maps services [closed]
I try to get two juxtaposed tiles in maps services like Google Maps or Bing Maps at a given zoom level (20 in my case). I managed to do it with those methods:
def meters_per_pixel_NS(lat, zoom):
...
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61 views
Optimizing projection for accuracy in calculating distances
I receive a set of LatLong points and I want to optimize the projection to Euclidean points so as to try to keep (distance in Euclidean space)/(greater circle distance in latLong) with variance as low ...
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60 views
Generate EPSG:4326 Vector Tiles
My goal is to create EPSG:4326 vector tiles (using Plate Caree) that can be served in Leaflet. I currently have a .shp file, which I converted to a geojson file using ogr2ogr. The main obstacle to ...
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1answer
100 views
proj: Oblique Mercator specifying two points on central line
I'm trying to use Oblique Mercator in QGIS 3.4, which uses proj to calculate coordinates conversion. I specify two points in the central line, rather than specifying the center and alpha.
Oblique ...
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1answer
424 views
Converting X and Y coordinates from Mercator world map (square) image to Latitude and Longitude
I'm using the following JS to transform Latitude and Longitude to X and Y coordinates but now I need the contrary, transforming Latitude and Longitude to X and Y.
export const latLon2xy = (lat, lon, ...
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2answers
140 views
Converting between coordinate systems but retain visual shape? [closed]
We have some data that is stored in GeoJSON format (using EPSG:4326), but now we want to display the data in the mapbox-gl-js, which only supports EPSG:3857 for display (support for other projections ...
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1answer
961 views
Using project / layer CRS in QGIS?
I'm using QGIS 3.4.1, and I'm trying to print 61km x 61km area map of somewhere South Korea. Then I need to send this map with west / east latitude and north / south longitude info to other person, ...
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91 views
Regular grid for whole planet
I`m trying to generate rectangular grid for whole world with fixed cell size in 350 meters (width and height are equals).
What i tried to do:
1) in main loop iterate trough longitude in range [-180; ...
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1answer
2k views
Mercator map coordinates transformation formula
I have a third-party application with a city map of size 131072x131072.
There are data on this map which contains x and y coordinates. I want to transform these coordinates to latitude and ...
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1answer
588 views
Angular rotation using Proj4, for local coordinate system
I have a polygon feature on map to which I need to transform the coordinates to local coordinate system with respect to new origin while keeping the same datum.
So far using the Proj4 library and by ...
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334 views
Map camera image onto sphere
How would I determine what the red point (phi', theta') is for a camera oriented at a known (phi, theta) is from a given image?
The point of this is to determine what (dphi, dtheta) is so that I can ...
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286 views
Calculate Latitude based on a mouse position on Mercator map
I have a similar question to the one found here, Mercator projection: formula for latitude based on pixels? The answer was very helpful but my question is just different enough that it doesn't quite ...
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1answer
60 views
Straight lines plotting as curves
I'm trying to do something really simple, plot a rectangle using psxy on a .cdf grid file. Something like:
grdimage grid.cdf -JM20c -R-70/0/20/60 -Bf20g10 -K > image.ps
psxy rectangle.dat -JM -R -B -...
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1k views
C# - convert lat long coordinates to WKT format
How can I convert coordinates to WKT format like 39.8251136,-8.3824103 with 900913 system (spherical Mercator)?
My client is askying me something like this: SRID=900913;POINT(-939520.0088637
4744291....
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1answer
144 views
Mercator - create uniformly distributed dots over map
I have a map in Mercator projection. I know coordinates of corners. I want to render uniformly distributed dots to map.
for (float latDeg = startLatDeg; latDeg <= endLatDeg; latDeg += stepLatDeg){
...
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112 views
Problem with parseWKT : projection mercator-2SP
1 -CoordinateReferenceSystem crss =
CRS.parseWKT("PROJCS[\"Mercator\",GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\","
+ "SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],"
...
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2answers
138 views
Why maps package adding straight lines in North America using mercator projection in r?
Why is this code creating a bunch of lines crossing the map?
map(database = "world",
proj="mercator",
fill=FALSE,
bg="white",
resolution=0)
How can I remove it without changing the ...
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1answer
57 views
problem converting OTF from Mercator to equal area
QGIS 1.8.0 on OSX 10.10.5: I've got continent outlines from Natural Earth that are in EPSG:4326 (degrees) plus USGS tree range data in EPSG:2030 (also degrees). When I set the project CRS to EPSG:4326 ...
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1answer
1k views
Converting EPSG to D3.js
Given an EPSG projection (say, this Alabama one: http://spatialreference.org/ref/epsg/26729/)
How can you take the given WGS84 projection bounds in such a way that you can use them in a D3.js ...
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1answer
3k views
Convert lat/lon to Mercator x/y, then measure distance
I'm attempting to convert latitude/longitude coordinates to X/Y coordinates on a 52,000 sq. ft. grid according to a simple Mercator projection. I used the following Python code to accomplish this, ...
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256 views
a localised 2D coordinate system from GPS coordinates
I spend a few days reading about coordinate systems, map projections, datums, etc. Since I am new to gis, I am not confident I am doing this right.
Problem at hand:
I have a GPS device that gives ...
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1answer
346 views
Generating perfect tile set from Mapbox for given zoom level?
I'm using Mapbox API to generate bitmap tiles.
First of all I have generated whole world tile with zoom 1 (seems it doesn't matter 0 or 1) and resolution 1280x1280. This tile perfectly positioned from ...
3
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1answer
375 views
gdal2tiles pixel shift in output tiles
I would like to re-calculate large geotiff files (10,000 x 10,000px) with the help of gdal2tiles into little (256 x 256px) tiles. The process works fine. However, the result is not perfect. There is ...
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2answers
2k views
Using pyproj and Mercator: x_0=0 and y_0=0?
I'm having a hard time figuring out how to project correctly from a Mercator projection to LAT/Lon.
Basically, I have a netCDF file with the following variables:
LON0 = 42.0 => reference longitude ...
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1answer
3k views
How does what3words build a grid of squares on the surface of the Earth?
What3words built a grid of squares of 3m2 on the earth. Does anyone know what is the algorithm ?
I started with this method: the range of longitude is [-180, 180] and the range of latitude is [-90,90]...
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1answer
2k views
How a draw a circle (on the surface of earth) on a mercator projection?
I would like to use R and leaflet to draw a circle (a real circle on the surface of the earth) on a mercator projection.
In the following code, I have the center of the circle (with lng=0 and lat=60),...
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167 views
QGIS Qtiles from EPSG 3395
I am having issues while converting my layer from 4326 to 3395. My Qtiles does not make tiles.
I have a source mapinfo in 4326 with long, lat pairs. My goal is to show this on a maps.yandex (3395 ...
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2answers
4k views
What's the accuracy of Web Mercator EPSG:3857?
Are there any references on the accuracy or (min/max/avg) error of Web Mercator when it comes to e.g. distance calculations?
For the sake of completeness, I haven't found any reference to the ...
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1answer
330 views
projecting onto Cartographic coordinates using Gauss Conformal Mercator in python
The shapefiles and boundaries I work with are on WGS 84 referenced to SA:
GEOGCS["WGS 84", DATUM["World Geodetic System 1984", SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]], ...
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1answer
1k views
How to quickly change EPSG in QGIS (Openlayers; 4326 vs. 3857)
I'm using Qgis 2.12.2-Lyon on Ubuntu 14.04 LTS.
With the OpenLayers plugin I added some OpenLayers to my Canvas.
I usually use the WGS 84 (EPSG:4326) projection for my project, but I have to switch ...
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1answer
3k views
Transforming lat and long to Mercator x and y
I've been trying to plot a set of lat and long coordinates to a Mercator map using the following set of equations:
x = long - long0
y = ln(tan(pi/4 + lat/2))
These equations are from a page on ...
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1answer
989 views
Formula of mapnik bounding box (spherical mercator)
I want to implement a tile server and I'm following the code in the repo node-mapnik-sample-code.
When a request is sent with the parameters x, y, z (longitude, latitude, zoom), those parameters are ...
2
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1answer
975 views
Map scale factor when converting from Mercator to Equirectangular
Lets say I have a map in Mercator projection, and I know top and bottom latitudes:
topLatitude = 80;
bottomLatitude = -55;
I also know width and height of a map:
width = 800;
height = 500;
I want ...
2
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1answer
4k views
Converting x,y on mercator to WGS84 latitude and longitude
How do I convert a particular point on a Mercator map (points in a Mercator map svg) to WGS84 coordinates? Is it simply a direct translation of the x,y values, using a multiplier which matches the map ...
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0answers
677 views
Geoserver Mercator to EPSG:4326
I have external WMS server, which have a layer pusblished in Mercator projection (EPSG:3395). I have this layer set up in Geoserver (2.8.1, GeoTools 14.1).
I need to expose this layer via WMTS in ...
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0answers
316 views
Flat Map that can go thru North Pole
Is there any map SDK or tool that can show the navigation that passes through the north pole in a flat way? Basically If I use a Mercator projection map it is only flat and cannot show the north part ...
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1answer
7k views
How to make a point from real latitude and longitude values
My program has a center point and one moving object . At this moment this point is somewhere in Europe.But Now i have to change that point from the latitude and longitude values(of Australia) . Please ...
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1answer
455 views
How to center a user-defined CRS on an area of interest?
My study extent in central Iran straddles two UTM zones (39 and 40):
I would like to create a user-defined CRS in Transverse Mercator projection with central meridian inside this area. Through ...
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3answers
6k views
Calculating Mercator coordinates from lat/lon
I am new to GIS but I am working on a project mapping a building using floor plans and JOSM.
Using the PicLayer plugin I added the .png floor plan as a layer.
I wrote a .cal file to set the scale, ...
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3answers
20k views
Adding additional geometry column in PostGIS?
I'm importing many sets of geodata into PostGIS, and they have different SRID's. (Some have EPSG:3857, some EPSG:4326, some something else).
I'd like to create an additional geometry column, eg. ...
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1answer
676 views
Overlay a raster image using Equirectangular projection (lat/lon) onto OSM/Google map with openlayers?
I have a forecast map of 6x6 lat/lon extend from 104E-110E, 10N-16N as an static PNG image and want to make it an overlay on the basemap of OSM/Google map using openlayers 3. The problem is OSM uses ...
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3answers
3k views
How did sailors navigate before the Mercator projection (1536)? [closed]
The Mercator projection (1536) must be great for nautical navigation. It allows one to find a bearing and keeping this constant one should reach the target (if not in the shortest line). But how did ...
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1answer
698 views
Convert from WGS84 to 2D projection
I have a map in the form of .bil & .hdr using WGS84. I'd like to convert this into another map using a 2D projection while keeping the lat/long information. What I'd really like with this new map ...
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1answer
557 views
Fixing mercator coordinates that are outside the world bounding box?
I'm using mercator-projected overlays from a crowdsourced website where volunteers georectify images of maps by hand. Unfortunately, the slippy map that serves as the site's interface wraps and allows ...
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1answer
86 views
gdaldem hillshade stop working with new projection?
Parallel to gdalwarp `-te -5.8 41 10 51.5 -ts 1980 0` not working with mercator? , my hillshade works with lat/long input :
gdaldem hillshade input.tmp.tif shadedrelief.tmp.tif -s 111120 -z 5 -az ...
3
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1answer
847 views
Which projections emphasise the Northern Hemisphere, other than Mercator?
I'm working on a project where I have data points in the UK, US, France/Italy, Hong Kong and Japan. I want to show a world map with mini charts at each of these locations.
For this project, it makes ...
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1answer
238 views
Extent from Centroids, Projection, and Resolution?
I have a file that defines a raster, although all the metadata was lost. I know the lat/long coordinates of the grid centroids, and that the grid is in a Mercator projection with a 1/12deg equatorial ...
