Why have standards, and what standards are needed

For space to become a commodity that is traded in an open market, purchasers will need to know that it is accurately measured. As a rough analogy, we expect when we pull up to a gas pump that the volume of gas delivered to our tank is accurately measured—and, in the United States, each state maintains a bureau of measurement standards that periodically certifies the accuracy of each gas pump in the state. The inspectors who validate the pumps do their work according to standards that specify: (1) how inspections are done (process standards) and (2) accuracy of measurement equipment (instrument standards).  The process standards include minimum qualifications of the inspectors themselves (training standards, licensing standards, continuing education standards, etc.).

Space measurement demands similar standards.

Mapping standards

In order to calculate space according to our definition, the boundaries of the space must be determined.One of the first standards is defi­ni­tion of the foil (the edges of open space). Foil defi­ni­tions differ by locale.Features that belong to the foil define the boundaries, so one of the first standards is definition of the foil, and this will vary depending on local condi­tions. For example, one locale may include only roads and permanent structures while another will add fences and navigable water features.

Space computations will be done in a Geographic Information System (GIS), so the data about foil boundaries must be gotten from a reliable source—an existing map, an image, or a new survey. Standards must establish greatest permissible position errors in these source products for the space calculation, as well as acceptable authorities for statements of positional accuracy. Mapping accuracy requirements couple with the resolution used in the space calculations themselves; for example, there is no point in requiring 1-meter mapping accuracy for a space calculation that will be done on a 100-meter grid.

While these considerations may seem daunting or even confusing to those not engaged in mapping, they are everyday matters for mapping and surveying professionals.

Calculation standards

Because GISes are software systems and there are multiple GIS developers, standards are needed that specify which software packages and functions are acceptable for space calculations1. Standards for these calculations may lay out a specific data processing flow (sequence of steps). For more information, see Measuring Space (Technical).

Standards may require a record of data processing steps, to be filed with other documents that create space credits, or in lieu of direct documentation, a statement that certifies the existence and permanent accessibility of such records.

1 At a higher level, a standards organization may specify standards—testing procedures and results requirements—for certification of GIS software packages for space calculations.