On 25 July 2013 02:41, Adam Wulkiewicz <email@example.com> wrote:In OGC (and ISO too) specifications of Simple Features, all attributes
> Does OGC allow negative dimensions? If not, should we assume that they won't
> be used in the future?
geometric dimensions are defined using signed integer.
In SQL/MM Spatial, an extension or predecessor of the latest OGC/ISO specs,
there is notion of ST_PrivateDimension for which the following rule is
a) If the ST_Geometry value corresponds to the empty set, then the
dimension is -1.
So, I'd draw conclusion, that OGC/ISO at least do not disallow
negative values here.
Behaviour of empty geometry vs empty set as in set theory might be confusing
(some details here http://trac.osgeo.org/postgis/wiki/DevWikiEmptyGeometry)