6.0.0 Release Notes¶
March 1st 2019
PROJ 6 has undergone extensive changes to increase its functional scope from a cartographic projection engine with so-called “early-binding” geodetic datum transformation capabilities to a more complete library supporting coordinate transformations and coordinate reference systems.
As a foundation for other enhancements, PROJ now includes a C++ implementation of the modelisation propopsed by the ISO-19111:2019 standard / OGC Abstract Specification Topic 2: “Referencing By Coordinates”, for geodetic reference frames (datums), coordinate reference systems and coordinate operations. Construction and query of those geodetic objects is available through a new C++ API, and also accessible for the most part from bindings in the C API.
Those geodetic objects can be imported and exported from and into the OGC Well-Known Text format (WKT) in its different variants: ESRI WKT, GDAL WKT 1, WKT2:2015 (ISO 19162:2015) and WKT2:2018 (ISO 19162:2018). Import and export of CRS objects from and into PROJ strings is also supported. This functionality was previously available in the GDAL software library (except WKT2 support which is a new feature), and is now an integral part of PROJ.
A unified database of geodetic objects, coordinate reference systems and their metadata, and coordinate operations between those CRS is now available in a SQLite3 database file, proj.db. This includes definitions imported from the IOGP EPSG dataset (v9.6.0 release), the IGNF (French national mapping agency) geodetic registry and the ESRI projection engine database. PROJ is now the reference software in the “OSGeo C stack” for this CRS and coordinate operation database, whereas previously this functionality was spread over PROJ, GDAL and libgeotiff, and used CSV or other adhoc text-based formats.
Late-binding coordinate operation capabilities, that takes metadata such as area of use and accuracy into account, has been added. This can avoid in a number of situations the past requirement of using WGS84 as a pivot system, which could cause unneeded accuracy loss, or was not doable at all sometimes when transformation to WGS84 was not available. Those late-binding capabilities are now used by the proj_create_crs_to_crs() function and the cs2cs utility.
A new command line utility, projinfo, has been added to query information about a geodetic object of the database, import and export geodetic objects from/into WKT and PROJ strings, and display coordinate operations available between two CRSs.
Removed projects.h as a public interface (#835)
Deprecated the proj_api.h interface. The header file is still available but will be removed with the next major version release of PROJ. It is now required to define
ACCEPT_USE_OF_DEPRECATED_PROJ_API_Hbefore the interface can be used (#836)
Removed support for the nmake build system (#838)
Removed support for the
proj_def.datdefaults file (#201)
C++11 required for building PROJ (#1203)
Added build dependency on SQLite 3.7 (#1175)
Added projinfo command line application (#1189)
Added many functions to
proj.hfor handling ISO19111 functionality (#1175)
Added C++ API exposing ISO19111 functionality (#1175)
Updated cs2cs to use late-binding features (#1182)
nad2binapplication. Now available in the proj-datumgrid git repository (#1236)
Removed support for Chebyshev polynomials in proj (#1226)
proj_geocentric_latitude()from proj.h API (#1170)
Changed behaviour of proj: Now only allow initialization of projections (#1162)
Changed behaviour of tmerc: Now defaults to the Extended Transverse Mercator algorithm (
etmerc). Old implementation available by adding
Chaged behaviour: Default ellipsoid now set to GRS80 (was WGS84) (#1210)
Allow multiple directories in
PROJ_LIBenvironment variable (#1281)
Added Lambert Conic Conformal (2SP Michigan) projection (#1142)
Added Bertin1953 projection (#1133)
Added Tobler-Mercator projection (#1153)
Added Molodensky-Badekas transform (#1160)
+t_obsparameter from helmert and deformation (#1264)
+dtparameter to deformation as replacement for removed
+towgs84values correctly on locales not using dot as comma separator (#1136)
Fixed file offset for reading of shift values in NTv1 files (#1144)
Avoid problems with
PTHREAD_MUTEX_RECURSIVEwhen using CMake (#1158)
Avoid raising errors when setting ellipsoid flattening to zero (#1191)
Fixed lower square calculations in rHealpix projection (#1206)
Allow Molodensky transform parameters to be zero (#1194)
Fixed wrong parameter in
ITRF2000init file (#1240)
Fixed use of grid paths including spaces (#1152)
Robinson: fix wrong values for forward path for latitudes >= 87.5, and fix inaccurate inverse method (#1172)
September 15th 2018
Added support for deg, rad and grad in unitconvert (#1054)
+t_epochas time input when not otherwise specified (#1065)
Added inverse Lagrange projection (#1058)
+multiplieroption to vgridshift (#1072)
Added Equal Earth projection (#1085)
Added “require_grid” option to gie (#1088)
+transposeoption of Helmert transform with
+convention. From now on the convention used should be explicitly written. An error will be returned when using the +transpose option (#1091)
Improved numerical precision of inverse spherical Mercator projection (#1105)
cct will now forward text after coordinate input to output stream (#1111)
Do not pivot over WGS84 when doing cs2cs-emulation with geocent (#1026)
Do not scan past the end of the read data in
proj_errno_string()is available in DLL (#1050)
Respect +to_meter setting when doing cs2cs-emulation (#1053)
Fixed unit conversion factors for geod (#1075)
Fixed test failures related to GCC 8 (#1084)
Improved handling of +geoc flag (#1093)
Calculate correct projection factors for Webmercator (#1095)
cs2cs now always outputs degrees when transformed coordinates are in angular units (#1112)
June 1st 2018
Validate units between pipeline steps and ensure transformation sanity (#906)
Print help when calling cct and gie without arguments (#907)
CITATION file added to source distribution (#914)
Webmercator operation added (#925)
Enhanced numerical precision of forward spherical Mercator near the Equator (#928)
--skip-linesoption to cct (#923)
Horizontal and vertical gridshift operations extended to the temporal domain (#1015)
NaNfloat cast overflow in
Avoid overflow when Horner order is unreasonably large (#893)
Avoid unwanted NaN conversions in etmerc (#899)
Avoid memory failure in gie when not specifying x,y,z in gie files (#902)
Avoid memory failure when
+sweepis initialized incorrectly in geos (#908)
HUGE_VALon erroneous input in ortho (#912)
Handle commented lines correctly in cct (#933)
Avoid segmentation fault when transformation coordinates outside grid area in deformation (#934)
Avoid doing false easting/northing adjustments on cartesian coordinates (#936)
Thread-safe creation of proj mutex (#954)
Avoid errors when setting up geos with +lat_0!=0 (#986)
Reset errno when running proj in verbose mode (#988)
Do not interpolate node values at nodata value in vertical grid shifts (#1004)
Restrict Horner degrees to positive integer values to avoid memory allocation issues (#1005)
March 1st 2018
Handle ellipsoid change correctly in pipelines when
+towgs84=0,0,0is set (#881)
Handle the case where nad_ctable2_init returns NULL (#883)
Avoid shadowed declaration errors with old gcc (#880)
+datumproperly in pipelines (#872)
Fail gracefully when incorrect headers are encountered in grid files (#875)
Improve roundtrip stability in pipelines using
Fixed typo in gie error codes (#861)
Numerical stability fixes to the geodesic package (#826 & #843)
Make sure that transient errors are returned correctly (#857)
Make sure that locally installed header files are not used when building PROJ (#849)
Fix inconsistent parameter names in
+vunitsis applied (#833)
Fix incorrect Web Mercator transformations (#834)
February 1st 2018
This version of PROJ introduces some significant extensions and improvements to (primarily) the geodetic functionality of the system.
The main driver for introducing the new features is the emergence of dynamic reference frames, the increasing use of high accuracy GNSS, and the related growing demand for accurate coordinate transformations. While older versions of PROJ included some geodetic functionality, the new framework lays the foundation for turning PROJ into 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 programming interface and a new command line utility, cct (for “Coordinate Conversion and Transformation”). The old programming interface is still available and can - to some extent - use the new geodetic transformation features.
The internal architecture has also seen many changes and much improvement. So far, these improvements respect the existing programming interface. But the process has revealed a need to simplify and reduce the code base, in order to support sustained active development.
Therefore we have scheduled regular releases over the coming years which will gradually remove the old programming interface.
This will cause breaking changes with the next two major version releases, 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 has ultimately been deemed necessary to ensure the long term survival of the project. Not only by improving the maintainability immensely, but also by extending the potential user (and hence developer) community.
The end goal is to deliver a generic coordinate transformation software package with a clean and concise code base appealing to both users and developers.
Versioning and naming¶
For the first time in more than 25 years the major version number of the software is changed. The decision to do this is based on the many new features and new API. While backwards compatibility remains - except in a few rare corner cases - the addition of a new and improved programming interface warrants a new major release.
The new major version number unfortunately leaves the project in a bit of a conundrum regarding the name. For the majority of the life-time of the product it has been known as PROJ.4, but since we have now reached version 5 the name is no longer aligned with the version number.
Hence we have decided to decouple the name from the version number and from this version and onwards the product will simply be called PROJ.
In recognition of the history of the software we are keeping PROJ.4 as the name of the organizing project. The same project team also produces the datum-grid package.
The PROJ.4 project provides the product PROJ, which is now at version 5.0.0.
The foundational component of PROJ is the library libproj.
Other PROJ components include the application proj, which provides a 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.
Introduced new API in
The new API is orthogonal to the existing
proj_api.hAPI and the internally used
The new API adds the ability to transform spatiotemporal (4D) coordinates.
Functions in the new API use the
Data types in the new API use the
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.
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.
The pipeline operator (
Helmert transform (
Horner real and complex polynomial evaluation (
Horizontal gridshift (
Vertical gridshift (
Molodensky transform (
Kinematic gridshift with deformation model (
Unit conversion (
Axis swap (
Central Conic projection (
Significant documentation updates, including
Overhaul of the structure of the documentation
A better introduction to the use of PROJ
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
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.
proj_api.h. Checks if an operation has an inverse. Use this instead of checking whether
P->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.
Fixed incorrect convergence calculation in Lambert Conformal Conic. (#16)
Handle ellipsoid parameters correctly when using
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)
-rflag when calling proj with
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 have been corrected for non-conformal projections. (#526)
Fixed scaling of cartesian coordinates in
Additional bug fixes courtesy of Google’s OSS-Fuzz program