This quote is in reference to a supposed split in the http://en.wikipedia.org/wiki/Dorsal_stream
The first was a 'coordinate system' that preserved metric information.
"Therefore, another type of spatial description of the object’s geometry
seems more useful, one that preserves invariant spatial information
by ignoring metric information. Indeed, many contemporary theories
of object identification (e.g., Marr, 1982; Biederman, 1987) assume that
objects are represented using such structural descriptions, which use
abstract types of spatial representati... (read more)
This quote is in reference to a supposed split in the http://en.wikipedia.org/wiki/Dorsal_stream The first was a 'coordinate system' that preserved metric information. "Therefore, another type of spatial description of the object’s geometry seems more useful, one that preserves invariant spatial information by ignoring metric information. Indeed, many contemporary theories of object identification (e.g., Marr, 1982; Biederman, 1987) assume that objects are represented using such structural descriptions, which use abstract types of spatial representati... (read more)