Provided by: proj-bin_9.5.1-1_amd64 
NAME
gie - The Geospatial Integrity Investigation Environment
SYNOPSIS
gie [ -hovql [ args ] ] file[s]
DESCRIPTION
gie, the Geospatial Integrity Investigation Environment, is a regression testing environment for the PROJ
transformation library. Its primary design goal is to be able to perform regression testing of code that
are a part of PROJ, while not requiring any other kind of tooling than the same C compiler already
employed for compiling the library.
-h, --help
Print usage information
-o <file>, --output <file>
Specify output file name
-v, --verbose
Verbose: Provide non-essential informational output. Repeat -v for more verbosity (e.g. -vv)
-q, --quiet
Quiet: Opposite of verbose. In quiet mode not even errors are reported. Only interaction is
through the return code (0 on success, non-zero indicates number of FAILED tests)
-l, --list
List the PROJ internal system error codes
--version
Print version number
Tests for gie are defined in simple text files. Usually having the extension .gie. Test for gie are
written in the purpose-build command language for gie. The basic functionality of the gie command
language is implemented through just 3 command verbs: operation, which defines the PROJ operation to
test, accept, which defines the input coordinate to read, and expect, which defines the result to expect.
A sample test file for gie that uses the three above basic commands looks like:
<gie>
--------------------------------------------
Test output of the UTM projection
--------------------------------------------
operation +proj=utm +zone=32 +ellps=GRS80
--------------------------------------------
accept 12 55
expect 691_875.632_14 6_098_907.825_05
</gie>
Parsing of a gie file starts at <gie> and ends when </gie> is reached. Anything before <gie> and after
</gie> is not considered. Test cases are created by defining an operation which accept an input
coordinate and expect an output coordinate.
Because gie tests are wrapped in the <gie>/</gie> tags it is also possible to add test cases to custom
made init files. The tests will be ignore by PROJ when reading the init file with +init and gie ignores
anything not wrapped in <gie>/</gie>.
gie tests are defined by a set of commands like operation, accept and expect in the example above.
Together the commands make out the gie command language. Any line in a gie file that does not start with
a command is ignored. In the example above it is seen how this can be used to add comments and styling to
gie test files in order to make them more readable as well as documenting what the purpose of the various
tests are.
Below the gie command language is explained in details.
EXAMPLES
1. Run all tests in a file with all debug information turned on
gie -vvvv corner-cases.gie
2. Run all tests in several files
gie foo bar
GIE COMMAND LANGUAGE
operation <+args>
Define a PROJ operation to test. Example:
operation proj=utm zone=32 ellps=GRS80
# test 4D function
accept 12 55 0 0
expect 691875.63214 6098907.82501 0 0
# test 2D function
accept 12 56
expect 687071.4391 6210141.3267
accept <x y [z [t]]>
Define the input coordinate to read. Takes test coordinate. The coordinate can be defined by
either 2, 3 or 4 values, where the first two values are the x- and y-components, the 3rd is the
z-component and the 4th is the time component. The number of components in the coordinate
determines which version of the operation is tested (2D, 3D or 4D). Many coordinates can be
accepted for one operation. For each accept an accompanying expect is needed.
Note that gie accepts the underscore (_) as a thousands separator. It is not required (in fact, it
is entirely ignored by the input routine), but it significantly improves the readability of the
very long strings of numbers typically required in projected coordinates.
See operation for an example.
expect <x y [z [t]]> | <error code>
Define the expected coordinate that will be returned from accepted coordinate passed though an
operation. The expected coordinate can be defined by either 2, 3 or 4 components, similarly to
accept. Many coordinates can be expected for one operation. For each expect an accompanying
accept is needed.
See operation for an example.
In addition to expecting a coordinate it is also possible to expect a PROJ error code in case an
operation can't be created. This is useful when testing that errors are caught and handled
correctly. Below is an example of that tests that the pipeline operator fails correctly when a
non-invertible pipeline is constructed.
operation proj=pipeline step
proj=urm5 n=0.5 inv
expect failure pjd_err_malformed_pipeline
See gie --list for a list of error codes that can be expected.
tolerance <tolerance>
The tolerance command controls how much accepted coordinates can deviate from the expected
coordinate. This is handy to test that an operation meets a certain numerical tolerance threshold.
Some operations are expected to be accurate within millimeters where others might only be accurate
within a few meters. tolerance should
operation proj=merc
# test coordinate as returned by ```echo 12 55 | proj +proj=merc``
tolerance 1 cm
accept 12 55
expect 1335833.89 7326837.72
# test that the same coordinate with a 50 m false easting as determined
# by ``echo 12 55 |proj +proj=merc +x_0=50`` is still within a 100 m
# tolerance of the unaltered coordinate from proj=merc
tolerance 100 m
accept 12 55
expect 1335883.89 7326837.72
The default tolerance is 0.5 mm. See proj -lu for a list of possible units.
roundtrip <n> <tolerance>
Do a roundtrip test of an operation. roundtrip needs a operation and a accept command to function.
The accepted coordinate is passed to the operation first in it's forward mode, then the output
from the forward operation is passed back to the inverse operation. This procedure is done n
times. If the resulting coordinate is within the set tolerance of the initial coordinate, the test
is passed.
Example with the default 100 iterations and the default tolerance:
operation proj=merc
accept 12 55
roundtrip
Example with count and default tolerance:
operation proj=merc
accept 12 55
roundtrip 10000
Example with count and tolerance:
operation proj=merc
accept 12 55
roundtrip 10000 5 mm
direction <direction>
The direction command specifies in which direction an operation is performed. This can either be
forward or inverse. An example of this is seen below where it is tested that a symmetrical
transformation pipeline returns the same results in both directions.
operation proj=pipeline zone=32 step
proj=utm ellps=GRS80 step
proj=utm ellps=GRS80 inv
tolerance 0.1 mm
accept 12 55 0 0
expect 12 55 0 0
# Now the inverse direction (still same result: the pipeline is symmetrical)
direction inverse
expect 12 55 0 0
The default direction is "forward".
ignore <error code>
This is especially useful in test cases that rely on a grid that is not guaranteed to be
available. Below is an example of that situation.
operation proj=hgridshift +grids=nzgd2kgrid0005.gsb ellps=GRS80
tolerance 1 mm
ignore pjd_err_failed_to_load_grid
accept 172.999892181021551 -45.001620431954613
expect 173 -45
See gie --list for a list of error codes that can be ignored.
require_grid <grid_name>
Checks the availability of the grid <grid_name>. If it is not found, then all accept/expect pairs
until the next operation will be skipped. require_grid can be repeated several times to specify
several grids whose presence is required.
echo <text>
Add user defined text to the output stream. See the example below.
<gie>
echo ** Mercator projection tests **
operation +proj=merc
accept 0 0
expect 0 0
</gie>
which returns
-------------------------------------------------------------------------------
Reading file 'test.gie'
** Mercator projection test **
-------------------------------------------------------------------------------
total: 1 tests succeeded, 0 tests skipped, 0 tests failed.
-------------------------------------------------------------------------------
skip Skip any test after the first occurrence of skip. In the example below only the first test will be
performed. The second test is skipped. This feature is mostly relevant for debugging when writing
new test cases.
<gie>
operation proj=merc
accept 0 0
expect 0 0
skip
accept 0 1
expect 0 110579.9
</gie>
STRICT MODE
New in version 7.1.
A stricter variant of normal gie syntax can be used by wrapping gie commands between <gie-strict> and
</gie-strict>. In strict mode, comment lines must start with a sharp character. Unknown commands will be
considered as an error. A command can still be split on several lines, but intermediate lines must end
with the space character followed by backslash to mark the continuation.
<gie-strict>
# This is a comment. The following line with multiple repeated characters too
-------------------------------------------------
# A command on several lines must use " \" continuation
operation proj=hgridshift +grids=nzgd2kgrid0005.gsb \
ellps=GRS80
tolerance 1 mm
ignore pjd_err_failed_to_load_grid
accept 172.999892181021551 -45.001620431954613
expect 173 -45
</gie-strict>
BACKGROUND
More importantly than being an acronym for "Geospatial Integrity Investigation Environment", gie were
also the initials, user id, and USGS email address of Gerald Ian Evenden (1935--2016), the geospatial
visionary, who, already in the 1980s, started what was to become the PROJ of today.
Gerald's clear vision was that map projections are just special functions. Some of them rather complex,
most of them of two variables, but all of them just special functions, and not particularly more special
than the sin(), cos(), tan(), and hypot() already available in the C standard library.
And hence, according to Gerald, they should not be particularly much harder to use, for a programmer,
than the sin()'s, tan()'s and hypot()'s so readily available.
Gerald's ingenuity also showed in the implementation of the vision, where he devised a comprehensive, yet
simple, system of key-value pairs for parameterising a map projection, and the highly flexible PJ struct,
storing run-time compiled versions of those key-value pairs, hence making a map projection function call,
pj_fwd(PJ, point), as easy as a traditional function call like hypot(x,y).
While today, we may have more formally well defined metadata systems (most prominent the OGC WKT2
representation), nothing comes close being as easily readable ("human compatible") as Gerald's key-value
system. This system in particular, and the PROJ system in general, was Gerald's great gift to anyone
using and/or communicating about geodata.
It is only reasonable to name a program, keeping an eye on the integrity of the PROJ system, in honour of
Gerald.
So in honour, and hopefully also in the spirit, of Gerald Ian Evenden (1935--2016), this is the
Geospatial Integrity Investigation Environment.
SEE ALSO
proj(1), cs2cs(1), cct(1), geod(1), projinfo(1), projsync(1)
BUGS
A list of known bugs can be found at https://github.com/OSGeo/PROJ/issues where new bug reports can be
submitted to.
HOME PAGE
https://proj.org/
AUTHOR
Thomas Knudsen
COPYRIGHT
1983-2024, PROJ contributors
9.5 01 Dec 2024 GIE(1)