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Questions tagged [proj]

A library for performing conversions between cartographic projections.

PROJ.4 is a library for performing conversions between cartographic projections written in C. The library is based on the work of Gerald Evenden at the USGS but is now an OSGeo project. The library ships with executables for performing the transformations from the command line.

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proj4's omerc projection (cs2cs) broken?

When I project longitude -60, latitude 0 to mercator, I get the expected answer: > echo "-60 0" | cs2cs +proj=lonlat +to +proj=merc -6679169.45 0.00 0.00 However, when I project it to oblique mercator with very similar parameters, I get a…
user1462
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Proj4 string for Hobo–Dyer projection?

I was fortunate to find an SVG of this projection at http://bl.ocks.org/mbostock/raw/4476487/ However, there appears to be little reference to this projection outside of wikipedia. Does anybody know what the Proj4 string would be?
J Tileson
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SRS: geographic or cartesian?

Let's have a list of SRS with proj4 definitions (e.g. spatial_ref_sys table). Is there a way to determine whether given SRS is geographic (lon,lat) or cartesian (x,y)?
romat2
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proj4 cookbook?

Is there a proj4 "cookbook"? I discovered proj4 from @MerseyViking excellent answer to: Create Mercator map with arbitrary center/orientation? but most of the documentation appears to be fairly high level. EDIT: Details on what I'm trying to do:…
user1462
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Creating local accurate projection for proj4?

We recently discovered that the UTM projection we have been using is not accurate enough for our application when doing calculations that require distances. Instead of rewriting our code base to use great circle calculation I would like to…
Poul K. Sørensen
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How to make PROJ4 on windows including NZ datum shift grids

Can anyone point me to an example of how to 'make' proj4 including the New Zealand datum shift grids? I understand I need to include the shift grids in the build, just not sure how to make it on windows.
tomtomnz
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What Proj.4 parameters have to be modified if the Y coordinates are shifted?

I would like to transform Barcelona map coordinates to Latitude, Longitude with Proj.4. I'm using EPSG number 23031 and the parameters are: +proj=utm +zone=31 +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs However, the Y coordinates in…
Valeria
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What parameters are useful for an Albers equal area projection map of the world

I have a data set which contains global points. I would like to convert from long/lat to Albers equal area. However, the http://spatialreference.org proj4 world parameter values are actually for the USA. Albers equal area might not be the best,…
user1544953
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How to define a local projection with correct altitude for correct area-metrics

Using PROJ, and defining custom projection, by its PROJ-strings. How to correct WGS84 altitude, to my "fit to local" reference? For example this Albers projection for Brazil: +proj=aea +lat_0=-12 +lon_0=-54 +lat_1=-2 +lat_2=-22 +x_0=5000000…
Peter Krauss
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Why is proj version dated in the future?

I compiled proj (also known as proj.4) from sources on Ubuntu (https://github.com/OSGeo/proj.4.git). I now wonder why is proj version dated in the future? E.g.: $ proj Rel. 6.0.0, March 1st, 2019 Edit: Same for proj version 6.1.0, which I…
swiss_knight
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compiling a c++ program using proj.4

I am real new to C++ and am having trouble compiling a C++ program that uses the proj.4 library. I downloaded and compiled and installed the proj.4 library on my machine. So, the /usr/local/lib'contains libproj.a libproj.la libproj.so ->…
Vish
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proj4 fails to create projection with "+units=degrees"

basically my problem is that pj_init_plus works fine with +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs but fails with +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +units=degrees I undestand there is a bit of overspecification there, but…
Slava
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Proj4js - no transformation for epsg2056

I have a script which converts local coordinates to WGS84. The script works fine if source data and source CS is epsg:21781. The CS for the data has changed now to epsg:2056. When I use epsg:2056 as source the point coordinate is not transformed at…
Rob_F
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Changing decimal places of X,Y coordinates using proj.4?

How do I change the accuracy of the output coordinates X,Y in the Proj.4 library (version 4.9)? In accordance with the manual I tried: proj +proj=poly -f '%.4f' +R=1 However, for lat=lon=50, the results '.4f' '.4f' indicate that the format has…
justik
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Proj4 Convert any CRS to ECEF

How can I convert a point in a given CRS I know, to ECEF, using Proj4? Is there an EPSG code for ECEF coordinates? Or is there a way to create a proj4 transform object to convert from and to ECEF coordinates?
manatttta
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