Exercise 6: Aerial Photography and Remote sensing

Subject: Principles of Cartography

Course Code: Geog 2003

Instructor: Dr. M. M. Yagoub

Photographic Sensors

Define Remote sensing?

“Remote sensing is the art, science, and technology of obtaining reliable information about physical objects and the environment, through the process of recording, measuring, and interpreting imagery and digital representation of energy patterns derived from non contact sensor system " .

 

List the main steps in Flight Plan and Photographic coverage?

•      Flight plan must calculate the total area to be covered, scale of photography, focal length of the camera to be used, flight height, forward and side over lap, ground distance for each flight line, number of photos, and other parameters

•       Usually 50-60% is recommended as forward overlap (End-lap) between successive photographs in the same flight-line

•      5-15% is recommended as a side lap between adjacent flight lines to prevent gaps in coverage of adjacent flight lines

•      Edge variations may occurred due to flight line drift (wind movement)

 

List the measurements that can be extracted from aerial photo

•      horizontal dimension on photo (distance, angle)

•      Height measurement and relief amplitude                  

 

How Height can be extracted from photos?

•      Height can be derived from two aerial photos (stereo) using stereoscopic instruments such as parallax, and stereo-plotter.

•      The photos must be on the same flight line

 

List the problems encounter in aerial photograph?

 

•      Tilt: Due to wind

•      Relief displacement: due to difference in height of objects

•      Shadow: better photography can  be taken during mid-day

 

Define the followings:

•      Orthophoto:  A photo that is free from tilt and distortion (relief displacement)

•      Mosaic : A series of adjacent photos overlapped together

•      Photomap/orthophotmap :  A mosaic with names and other information  added

 

List the main  Equipment used in digital photogrammetry?

•      Equipment used in digital photogrammetry include Computer, Scanner, CCD cameras, LCD Eyewear (stereo viewing)

 

Discuss how photogrammetry can be applied to study urban growth?

Historical aerial photographs imagery can be classified and integrated with GIS to show the historical development of a city

 

Discuss briefly Landsat 4-5 satellite characteristics?

 

•      Launched in 1982 at an altitude of 705 Km

•      Onboard sensors are MSS (80m) and Thematic Mapper (TM) with 6 bands and resolution 30m and one band in the Infra-Red (IR) with a resolution of 120m

•      Ground swath width 185 Km

•      Temporal resolution 16 days

 

Discuss briefly Landsat 7 satellite  characteristics?

 

•      Launched on 15 April 1999 at an altitude of 705 Km

•      Onboard sensors are (TM 30m) and Enhanced Thematic Mpper plus (ETM+) with a resolution of 30m, 15m in panchromatic band and Thermal IR with 60m resolution

•      Ground swath width 185 Km

•      Temporal resolution 16 days

•      Joint program between NASA, NOAA, and USGS

   

 

Discuss briefly The SPOT satellite characteristics

 

•      SPOT 1,2,3,4  launched in 1986, 90,93, 97 and SPOT 5 will be launched by 2001

•      Altitude of 822 km, inclination 98 deg. (i.e near-polar orbit)

•      The orbital plane have  a constant angle relative to the Sun direction (sun-synchronous)

•      Temporal resolution 26 days

•      Onboard sensors are identical HRV  (High Resolution Visible) imaging instruments

•      The unique characteristics of SPOT imagery is the ability to obtain Stereoscopic View -important in 3D applications

 

Write the full term for the following abbreviations:

 

•ISPRS: International Society for Photogrammetry and Remote Sensing

•NASA -National Aeronautic and Space Administration

•ESA- European Space Agency (Europe)

•NASDA- National Space Development Agency (Japan)