Remote Sensing

Front 1

What are the two common types of remotely sensed data

Back 1

Aerial Imagery

Satellite Imagery

Front 2

Basic Principles of Remote Sensing

Back 2

Based on reflected electromagnetic energy

Objects reflect, absorb, or transmit energy

Objects appear as the color they most reflect

Front 3

What is Albedo?

Back 3

the reflective quality. 0% means nothing is reflected and 100% is total reflectance

Front 4

Two types of remote sensing systems and definitions

Back 4

1. Passive = relies on a sun's energy, does not penetrate clouds

2. Active = can penetrate clouds but needs energy source

Front 5

Active systems

1.

2.

Back 5

Radar - Active System

radio detection and ranging

one wavelength (monochromatic)

LiDAR - Active

light detection and ranging

higher resolution than radar

Front 6

What is Photogrammetry?

Back 6

science of measuring geometry from images

aerial imagery used primarily

Front 7

Aerial Image Attributes

Back 7

Image Scale = relative distance on image to distance on ground, non uniform scale across image

Image resolution = smallest object that can be reliably detected on an image

Front 8

Different types of film used for aerial images

Back 8

Panchromatic = b/w inexpensive

True color = sensitive to light across spectrum/expensive

Infrared = sensitive to visible and infrared light, used for vegetation

Front 9

benefits of Digital aerial cameras

Back 9

Quickly replace film (eliminate conversion)

Uses Charge Coupled Device (CCD)

Front 10

Geometric Quality of Aerial Images

Back 10

All aerial images will contain distortion

Orthographic photo - been corrected for distortion, plotted positions after being projected

Front 11

Photogramitrist

Back 11

some one who fixes a distorted image

Front 12

Aerial image distortion causes are?

1-6

Back 12

Terrain = major

camera tilt = major

film deformation = minor

camera lens= minor

atmospheric bending = minor

other = minor

Front 13

Terrain distortion

Back 13

cause relief displacement

Further you travel from center the distortion gets greater radially

Scale is not constant

Front 14

Camera Tilt Distortion

Back 14

when the optical axis point is in a non-vertical angle

results in perspective convergence

Tilt three angles is pitch yaw and roll

Front 15

Other Errors

Back 15

Radial Lens displacement - imperfections in camera lens surface

Systematic errors (ex: deformed platten)

Atmospheric Distortion - bending light

Front 16

Geometric Correction

Back 16

Photogrammetry provides tools needed to remove geometric distortion

correction process requires measurement of image coordinates and ground coordinates

all equals orthographic image

Front 17

Primary Uses of Aerial Images

Back 17

Basis for surveying and topo mapping

Image/Photo interpretation

Backdrop for maps

Front 18

What is Photointerpretation

Back 18

Process of converting images into information

Interpret size, shape, color, brightness, texture, relative location

Requires Minimum Mapping Unit (MMU)

- executed through on screen digitizing or hardcopy interpretation

Front 19

What is the name for two overlapping stereo images?

Back 19

Stereo Pair

Endlap - overlap in flight line

Overlap - overlap in adjacent flight lines

Front 20

What is parallax

Back 20

shift in relief displacement due to the shift in the observer position

(displacement of any given point is different on the left vs. right ground views)

Front 21

What is a stereomodel

Back 21

3D perception of terrain that we see when viewing a stereopair

Front 22

Differences between satellite from aerial images

Back 22

Pros:

- Higher spectral ranges

- Reduced terrain distortion

- Cover large areas

Cons:

- May require specialized processing

- Lower effective resolution

- image acquisition must be planned days in advance

- Expensive

Front 23

What is MODIS?

Back 23

Collects data at a range of wavelengths