Tribblix: manual page: gie.1

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.

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)