gie(1) PROJ gie(1)
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
1983-2023
9.2.1 June 1, 2023 gie(1)
proj 9.2.1 - Generated Tue Jun 13 10:26:53 CDT 2023