Discussion

Aubert – GEOG 300

Remote Sensing (RS)

Remote sensing is the collection of images and data from a distance, usually

from instruments flying above the Earth (for example, in airplanes, satellites,

and/or the International Space Station). Remote sensing instruments most

commonly detect reflected sunlight (like a photograph!), emitted longwave

(like night vision infrared goggles!), or backscatter (like radar!).

• A passive sensor reads only naturally occurring energy (such as

reflected sunlight and emitted longwave).

• An active sensor reads only backscatter, which is the term for the

energy reflected back at the sensor after it blasts pulses of energy

(like radio waves) at Earth.

Global Positioning System (GPS)

The Global Positioning System includes two main components. The first is a

network of 24 space based satellites which sends out timed signals. The

second is ground-based receivers which read these signals and calculate and

record exact location data. If a GPS ground receiver is moving (for example, in

a car), speed and direction can also be calculated.

• Data collected and stored by a GPS receiver can be fed into a

Geographic Information System (GIS) to create digital maps. See

more below.

• The GPS receiver alone cannot navigate or give directions. It can,

though, feed your real-time location into a GIS (interactive digital

map) which can then navigate and give directions. See below.

Geographic Information System (GIS)

A Geographic Information System (GIS) is a computer program which can

create interactive, digital maps which are able to display and analyze spatial

(mapped) data. The data in a GIS can come from scanning (digitizing) paper

maps, but more commonly it now comes directly from GPS and remote

sensing instruments. This is exactly the type of technology which has been

used to build Google Earth, Google Maps, and other online mapping

applications.

Remember, a GPS receiver alone cannot navigate or give directions. It can,

though, feed your real-time location into a GIS (interactive digital map) which

can then calculate, navigate and give directions. In other words, modern

navigation devices must combine both GIS and GPS!

A Simplified Introduction to Common

GEOSPATIAL TECHNOLOGIES

Remote Sensing data is used

to create maps in a GIS…

GPS data is also used to

create maps in a GIS…