5210 exam 2 study 2

What are the advantages/disadvantages of satellite imaging systems relative to aerial imaging systems?

++ very high perspective, which significantly reduces terrain caused distortion ++very precise control of pointing direction disadvantages cost may be high if only a small area is desired acquisition is less flexible, relative to a pilot flying on short notice

what are the advantages and disadvantages of using UAVs/drones?

+++ low cost high data resolutions --limited datat collection rates

Aerial photographs are captured with how much overlap? Illustrate. _________sidelap __________endlap

20-30% sidelap 60% endlap These help prevent lack of coverage because of drift and crab

An image must be captured with less than_____ of tilt to be considered "vertical"

3 degrees

What is LiDAR?

Laser shot down from an arieal platform to measure height. The strength and time of return is used to estimate height of canopy, mountain etc..

Satellite scene location may be specified by a path/row number, because a set of approximately ______paths are designated, with approximately ___________rows identified across the paths

North south East west

The orbits of imaging satellites are usually_________and ____________________

Polar Sun synchronous

What is a stereopair? What is parallax?

Stereo pairs- over lap photos Parallax- Apparent change in the position of an object on an air photo because of a change in the position of observation

What are the primary sources of distortion in aerial photographs and satellite images?

Terrain camera tilt

How is imagery typically collected by a satellite

across track direction, __perpendicular___ to the flight path __Along Track__ directon, parallel___to the flight path AKA push broom

What does discrete return LiDAR collect?

collects x,y,z coordinates for 3 dimenational space result= point cloud

Why were infrared sensors originally developed?

developed by military for camouflage detection purposes original concept was to separate signatures for live vegetation from simulated vegetation

What is the difference between a true color image and a false color infrared image?

false color - there is infrared incorporated

How are false color images created?

green, red, and near infrared channels of the image are assigned the blue, green, and red colors in a computered displayed system Referred to as false color images

What are the approximate resolutions of "high", "medium", and "coarse" resolution satellite systems?

high= finer than 3m Medium = 5m - 100m coarse= more than 100m

solar radiation is either

infrared ultraviolet ...??

What is the difference between low oblique and high oblique?

low- horizon is not shown High-horizon is shown

What is the difference between orthographic view and perspective view?

ortho- looking down at all locations ( google maps) Perspective- being able to see the sides of buildings ( air plane view)

What is the difference between passive and active sensors?

passive- run off of renewable energy Active- operate at night -sonar, radar, Lidar

What are the elements of photointerpretation?

size- Shape Shadow Tone/color Texture Pattern Site, situation, and association

Explain spectral reflectance curves

surface features color can be characterized by the % of energy it reflects

What are sources of distortion in aerial photographs and satellite images?

terrain Camera tilt Film deformation Camera lens Sensor defects or other camera errors Atmospheric bending

What are the common characteristics of terrain distortion in vertical images?

terrain distorions are radial Relief distortions affect angles and distances on an image Scale is not consistent on aerial images A vertical aerial image taken over varied terrain is not orthographic

Differentiate roll, pitch, and yaw. Illustrate. Which result in tilt distortion?

tilt results in roll and pitch Yaw: does not result in tilt

What is the most common form of solar radiation emitted by the sun?

ultraviolet

What does the red on a false color infrared image indicate?

vegetation

What is the difference between vertical, oblique, and horizontal?

vertical- taken staright down, like a map Oblique- taken at an angle