High Resolution 1:10,000 scale Mapping Strategy of Multi ... - NDMA

Formerly known as PUCC, the Digital Map Owners Group (DMOG) is a nine member
sub-committee of the Toronto
Public Utility Co-ordinating Committee (TPUCC), sharing in the cost of maintenance of
the underground utilities of the former City of Toronto.
DTM
A Digital Terrain Model is a land surface represented in digital form by an elevation grid
or lists of three-dimensional coordinates.
ESM
The City’s Enterprise Stereoscopic Model (ESM) delivers digital photogrammetry to the
desktop as a fully oriented 3D
image for the amalgamated City of Toronto. The ESM is the primary environment for
maintaining 2D/3D topographic mapping, high-resolution orthoimagery and Toronto
Mono Viewer(TMV). The City’s Digital Terrain Model (DTM) is collected and maintained
in ESM environment.
GEOGRAPHIC COORDINATE SYSTEM
A system used to measure horizontal and vertical distances on a planimetric map. The
City of Toronto’s operational coordinate system is currently the Modified Transverse
Mercator (MTM) projection, North American Datum 1927 (NAD27), with a truncated
northing or y value (-4,000,000).
GEOREFERENCING
A process of assigning map co-ordinates to image data to conform to map projection
grid.
LARGE-SCALE
A description used to represent a map or data file having a large ratio between the area
on the map and the area that is represented. If the map the size of this page shows only
a small area such as your house, it would be described as large scale mapping.
MAP SCALE
The ratio of a distance on a map to the true distance on the ground. For example, if the
map scale is 1:1000, 1cm on the map represents 10 m on the ground. See also Design
Scale.
MAP PROJECTION
A mathematical model that transforms the locations of features on the Earth's surface to
locations on a two-dimensional surface. Because the Earth is three-dimensional, some
method must be used to depict a map in two dimensions.