User:Mav/Data Acquisition in GIS notes by maveric149/2002-04-12 Lecture

Data Acquisition in GIS notes by maveric149 2002-04-12 Lecture

Remote sensing

Coined in the late 1940s

• two types: Active (Radar, SLAR, SNAP, sonar, LIDAR), and Passive (Landsat, Ikonos, GOES, Earth Imagin Satellites, Aerial photography, Sonar)

Resolution

Most important thing is that the resolution actually solve the problem. It will cost too much money to have too much resolution. Dimensions of Resolution 1) Spatial 2) Spectral 3) Radiometric 4) Temporal 5) Thematic

Spectral =

Type of energy
Moderate = black and white, High = IR, very high = used to detect mineral types.

IR light radiation is good to use to image vegetation -- the rays bounce off of internal structures within the leaf. Different species of plants will reflect at slightly different wavelinks.

Radiometric

Intensity of of energy or number of levels of brightness
Landsat has 256 levels of brightness, human eye can distinguish 120 and B&W film has 60 levels.

Temporal

None of the other dimensions of resolution matter if you miss what you are supposed to measure. In a low resolution temporal system, you may miss short lived phenomenon.

Thematic

Describes what specifically you are looking for, or its theme. Synthesizing general data to specific data that can be used to solve a problem.