A macro is an automated method of using a Geographical Information System. Commands and parameters are entered into a text file to produce a desired outcome.
The advantages of using macros include:-
Efficiency and Accuracy: A process can be repeated many times without the need to re-enter commands and parameters into instruction input fields. The result is an increased in efficiency and accuracy. The efficiency comes from the saving in operators time while the accuracy is the result of the avoidance of repetitive operations which results in miss keyed, double entry or missed entry of required data.
Repeatability: Operations may be repeated many times with variations in
particular parameters. An example of this is the exercise performed at GBRMPA by Mick
Hartcher to determine which areas of the marine park could be at risk from catamarans,
sailboards and other small craft. When updated information became available, after he had
left that organisation, another operator could have used a macro of his work, to input the
new data into the parameter, which contained the range of these craft.
Sandra Sherriff could set up a macro, which could be used to identify all underground services. Staff not trained in GIS could, by entering one simple parameter, which contains the reference details of the land under consideration, produce a map of these services and hence avoid damage when excavations are proposed.
Decisions could be made to determine a best result, given a set of options, which could be input as parameter changes into a macro. Or a macro could be used with a different set of input files so as to achieve Consistency between successive operations.
Verification: The macro can be stored with the hard copy of the resultant files for future examination, particularly when there is some doubt cast on the validity of derived data.
Speed: An experienced operator can write a macro file in a shorter time than it takes to call various entry screens wait for them to open, enter date in a variety of fields and wait for the processing of that data. With a macro entries are performed contemporaneously with no need to wait between entries, the processing of the macro occurs contiguously with respect to time and at the end of the entry process, by which time the operator has finished their work and is available to start the next task.