Chapter4 Flashcards
(13 cards)
What the DTM: Terminology Background
(1) Digital Elevation Model (DEM)
(2) Digital Height Model (DHM)
(3) Digital Ground Model (DGM)
(4) Digital Terrain Model (DTM)
(5) Digital Terrain Elevation Data (DTED)
(6) Digital Surface Model (DSM)
(1) Digital Elevation Model (DEM):
(2) Digital Height Model (DHM):
(1) Elevation measures height above a datum, indicating the absolute altitude of points in the model.
(2) A less common term for DEM, as elevation and height are typically synonymous.
What the DTM: Elements
(1) DTM Generation
(2) DTM Manipulation
(3) DTM Interpretation
(4) DTM Visualization
(5) DTM Applications
The basic data for a DTM is based on terrain elevation
observations that are derived generally from:
(1) Hydrographic Surveying
(2) LIDAR
(3) RADAR
Explain the DTM Generation: Digitized Contours
DTMs from contours are common, digitized from analog maps and processed with elevation values.
What the Ground Surveying
Ground surveying measures and maps the Earth’s surface using on-site tools.
Ground (Field) Surveying techniques include:
Ground surveying uses total stations, differential levels, and GPS (RTK) to measure points and features.
What the DTM Application Domains
(1) Hydrographic Surveying
(2) Civil Engineering
(3) Earth Sciences
(4) Military Applications
What the Typical Applications of DTMs:
Given (X,Y) estimate/find Z.
● Generation of profiles.
● Contour line estimation.
● Determination of a line-of-sight.
What the Conditions for A Surface Model:
(1) Accurately represent the surface.
(2) Be suitable for efficient data collection
(3) Minimize data storage requirements
What the DTM Data Models:
(1) Contour Lines.
(2) Grids (Matrix Structure or a Lattice)
(3) Triangulated Irregular Networks (TINs)
What The TIN data model elements are:
- nodes
- edges
- triangles
- topology
What are Visualization techniques:
Static visualization for basic communication of results.
Animations show change; fly/walk-throughs offer immersion
