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
Run all tests in a file with all debug information turned on
gie -vvvv corner-cases.gie
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 eachaccept
an accompanyingexpect
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 oneoperation
. For eachexpect
an accompanyingaccept
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
shouldoperation 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 aoperation
and aaccept
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 donen
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 beforward
orinverse
. 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 nextoperation
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
Added 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.