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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1answer
14k views

Calculating distance scale factor by latitude for Mercator

This was really inconvenient topic to google out - so I'm asking for clarification, did I understood things correctly. I'm talking about measuring short distances in Mercator projection (3857). You ...
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3answers
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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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3answers
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Mercator: scale factor is changed along the meridians as a function of latitude?

"In Mercator projection the scale factor is changed along the meridians as a function of latitude" How to calculate the Mercator scale factor as a function of the latitude in decimal degrees ? I ...
4
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1answer
5k views

Re-project raster image from Mercator to Equirectangular

I have a raster image of the world map in Mercator projection, square 1:1 format. I want transform the image into an Equirectangular projection accurately. I assumed from my research that GDAL would ...
3
votes
1answer
4k views

Mercator projection: formula for latitude based on pixels?

I am basing this question on knowledge from a previous one: Mercator projection: problem with latitude formula In that question/answer, the formula is given for working out how many pixels above/...
18
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1answer
2k 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]...
6
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2answers
3k 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 ...
5
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2answers
11k views

Making geotiff and reprojecting to EPSG:4326 using GDAL?

My goal is to download a gif file from this webpage: http://aviationweather.gov/data/iffdp/2104.gif Then crop it to the known latlon bounds of 75N,45S,35W,70E, convert to geotif, and then project to ...
4
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1answer
3k views

Re-projecting from Polar projection to EPSG:4326?

I simply want to project a polar stereographic raster (EPSG:3411) to Mercator (EPSG:3857) or WGS84 (EPSG:4326). The data I is from NOAA. $gdalwarp -s_srs EPSG:3411 -t_srs EPSG:3857 northpsg.20141027 ...
1
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1answer
2k views

Converting mercator meters without UTM zone?

I've been attempting to extract track information from Humminbird (Side Imaging Sonar) binary files and have hit a stumbling block with the coordinates it provides. The values are apparently in ...
0
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1answer
916 views

Gdal: How to reproject from equirectangular to mercator?

I work with raster ETOPO1, made a crop of my area of interest. curl -L -C - 'http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/grid_registered/georeferenced_tiff/ETOPO1_Ice_g_geotiff....