PROJ 5.0.0¶
February 1st 2018
This version of PROJ introduces some significant extensions andimprovements to (primarily) the geodetic functionality of the system.
The main driver for introducing the new features is the emergence ofdynamic reference frames, the increasing use of high accuracy GNSS,and the related growing demand for accurate coordinatetransformations. While older versions of PROJ included some geodeticfunctionality, the new framework lays the foundation for turning PROJinto a generic geospatial coordinate transformation engine.
The core of the library is still the well established projection code.The new functionality is primarily exposed in a new programminginterface and a new command line utility, cct(for “Coordinate Conversion and Transformation”). The old programming interface isstill available and can - to some extent - use the new geodetictransformation features.
The internal architecture has also seen many changes and muchimprovement. So far, these improvements respect the existingprogramming interface. But the process has revealed a need to simplifyand reduce the code base, in order to support sustained activedevelopment.
Therefore we have scheduled regular releases over the coming yearswhich will gradually remove the old programming interface.
This will cause breaking changes with the next two major versionreleases, which will affect all projects that depend on PROJ(cf. section “deprecations” below).
The decision to break the existing API has not been easy, but hasultimately been deemed necessary to ensure the long term survival ofthe project. Not only by improving the maintainability immensely, butalso by extending the potential user (and hence developer) community.
The end goal is to deliver a generic coordinate transformationsoftware package with a clean and concise code base appealing toboth users and developers.
Versioning and naming¶
For the first time in more than 25 years the major version number ofthe software is changed. The decision to do this is based on the manynew features and new API. While backwards compatibility remains -except in a few rare corner cases - the addition of a new and improvedprogramming interface warrants a new major release.
The new major version number unfortunately leaves the project in a bitof a conundrum regarding the name. For the majority of the life-timeof the product it has been known as PROJ.4, but since we have nowreached version 5 the name is no longer aligned with the versionnumber.
Hence we have decided to decouple the name from the version number andfrom this version and onwards the product will simply be called PROJ.
In recognition of the history of the software we are keeping PROJ.4 asthe name of the organizing project. The same project team alsoproduces the datum-grid package.
In summary:
The PROJ.4 project provides the product PROJ, which is now atversion 5.0.0.
The foundational component of PROJ is the library libproj.
Other PROJ components include the application proj, which providesa command line interface to libproj.
The PROJ.4 project also distributes the datum-grid package,which at the time of writing is at version 1.6.0.
Updates¶
Introduced new API in
proj.h.The new API is orthogonal to the existing
proj_api.hAPI and the internally usedprojects.hAPI.The new API adds the ability to transform spatiotemporal (4D) coordinates.
Functions in the new API use the
proj_namespace.Data types in the new API use the
PJ_namespace.
Introduced the concept of “transformation pipelines” that makes possible to do complex geodetic transformations of coordinates by daisy chaining simple coordinate operations.
Introduced cct, the Coordinate Conversion and Transformation application.
Introduced gie, the Geospatial Integrity Investigation Environment.
Selftest invoked by
-Cflag in proj has been removedPorted approx. 1300 built-in selftests to gie format
Ported approx. 1000 tests from the gigs test framework
Added approx. 200 new tests
Adopted terminology from the OGC/ISO-19100 geospatial standards series. Key definitions are:
At the most generic level, a coordinate operation is a change of coordinates, based on a one-to-one relationship, from one coordinate reference system to another.
A transformation is a coordinate operation in which the two coordinate reference systems are based on different datums, e.g. a change from a global reference frame to a regional frame.
A conversion is a coordinate operation in which both coordinate reference systems are based on the same datum, e.g. change of units of coordinates.
A projection is a coordinate conversion from an ellipsoidal coordinate system to a plane. Although projections are simply conversions according to the standard, they are treated as separate entities in PROJ as they make up the vast majority of operations in the library.
New operations
The pipeline operator (
pipeline)- Transformations
Helmert transform (
helmert)Horner real and complex polynomial evaluation (
horner)Horizontal gridshift (
hgridshift)Vertical gridshift (
vgridshift)Molodensky transform (
molodensky)Kinematic gridshift with deformation model (
deformation)
- Conversions
Unit conversion (
unitconvert)Axis swap (
axisswap)
- Projections
Central Conic projection (
ccon)
Significant documentation updates, including
Overhaul of the structure of the documentation
A better introduction to the use of PROJ
A complete reference to the new API
a complete rewrite of the section on geodesic calculations
Figures for all projections
New “free format” option for operation definitions, which permits separating tokens by whitespace when specifying key/value- pairs, e.g.
proj = merc lat_0 = 45.Added metadata to init-files that can be read with the proj_init_info() function in the new
proj.hAPI.Added ITRF2000, ITRF2008 and ITRF2014 init-files with ITRF transformation parameters, including plate motion model parameters.
Added ellipsoid parameters for GSK2011, PZ90 and “danish”. The latter is similar to the already supported andrae ellipsoid, but has a slightly different semimajor axis.
Added Copenhagen prime meridian.
Updated EPSG database to version 9.2.0.
Geodesic library updated to version 1.49.2-c.
Support for analytical partial derivatives has been removed.
Improved performance in Winkel Tripel and Aitoff.
Introduced
pj_has_inverse()function toproj_api.h. Checks if an operation has an inverse. Use this instead of checking whetherP->invexists, since that can no longer be relied on.ABI version number updated to 13:0:0.
Removed support for Windows CE.
Removed the VB6 COM interface.
Bug fixes¶
Fixed incorrect convergence calculation in Lambert Conformal Conic. (#16)
Handle ellipsoid parameters correctly when using
+nadgrids=@null. (#22)Return correct latitude when using negative northings in Transverse Mercator. (#138)
Return correct result at origin in inverse Mod. Stereographic of Alaska. (#161)
Return correct result at origin in inverse Mod. Stereographic of 48 U.S. (#162)
Return correct result at origin in inverse Mod. Stereographic of 50 U.S. (#163)
Return correct result at origin in inverse Lee Oblated Stereographic. (#164)
Return correct result at origin in inverse Miller Oblated Stereographic. (#165)
Fixed scaling and wrap-around issues in Oblique Cylindrical Equal Area. (#166)
Corrected a coefficient error in inverse Transverse Mercator. (#174)
Respect
-rflag when calling proj with-V. (#184)Remove multiplication by 2 at the equator error in Stereographic projection. (#194)
Allow +alpha=0 and +gamma=0 when using Oblique Mercator. (#195)
Return correct result of inverse Oblique Mercator when alpha is between 90 and 270. (#331)
Avoid segmentation fault when accessing point outside grid. (#396)
Avoid segmentation fault on NaN input in Robin inverse. (#463)
Very verbose use of proj (
-V) on Windows is fixed. (#484)Fixed memory leak in General Oblique Transformation. (#497)
Equations for meridian convergence and partial derivatives havebeen corrected for non-conformal projections. (#526)
Fixed scaling of cartesian coordinates in
pj_transform(). (#726)Additional bug fixes courtesy of Google’s OSS-Fuzz program
