Data capture from above:GPS and remote sensing Global positioning systems    Aerial photography     Satellite imagery
Global positioning system (GPS)• Current system run by USA military• Gives normal accuracy of ~5m• European alternative ca...
Global Positioning Systems (GPS) satellite based navigation                           • 24 satellites in orbit, 21        ...
Important points to note about GPS• The satellites transmit data which is  picked up by the user’s receiver on the  ground...
GPS based yield mapping at the RAC                      GPS satellitesGPS data:location of yield samples                  ...
Mapping yield levelsYield class maps for sixadjoining plots. The yielddata, shown in colour, comesfrom the yield meter, al...
Examples of data collection: GPS data collection        Mobile GPS and data recorder               Weed patch centroids, e...
Examples of GPS use by US Geological survey
Remote sensing what is it?• Observation from a distance  – Aerial photographs- very detailed  – Satellite images – global ...
Oblique aerial photograph• Viewed from an oblique angle: looking  sideways• Looks natural, easy to understand,  useless fo...
Vertical aerial photograph• Viewed straight down giving a “map view”• Difficult to understand at first. Can be used  as a ...
Aerial photographs: 1995 and 1972
Map derived form aerial photographs• Visible features are “digitised” by tracing  around them on a computer screen.• This ...
Stereo-photography 3-d visualisation• Overlapping aerial photographs can be used to build  3-d stereoscopic visual models....
Stereoscopic reconstruction of overlapping areas• A stereoscope is used to view the overlapping areas  simultaneously and ...
Digital manipulation of aerial photographs• 3-d models can also be built by “digitally draping”  photographs over a digita...
Sources of aerial photographs• UK aerial photography is available  on-line, or can be commissioned• www.getmapping.com is ...
Satellite Remote Sensing• Satellites give a higher viewpoint and give  unrestricted coverage of the whole globe           ...
Satellite orbits• Geostationary orbit: above the equator,  35,000 km height, orbital period 24  hours. Satellites appear f...
Geo-stationary meteorological satellite: Meteosat• Geostationary orbits, approx 33,000 km elevation  over the equator. Sat...
Polar orbiting meteorological satellites• Polar orbiting satellites cover the whole globe, but  move, so there are long ti...
Earth observation satellites: Landsat 7 image (30m resolution)• Earth observation satellites are designed to view the  sur...
2004 tsunami: Aceh province, Sumatra
Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to  classify l...
Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to  classify l...
Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to  classify l...
Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to  classify l...
Remote  sensing  images:Harnhill farm
Aerial photograph, 2011Spatial resolution approx. 0.2m
GoogleMaps aerial photo,Spatial resolution approx. 1.5m
Scanned Aerial photograph, 1995Spatial resolution approx. 2.0m
Landsat 5 image, circa 2001Spatial resolution approx. 30m
LIDAR image, 2011Spatial resolution approx. 1.0mVertical resolution approx. 0.001m
Landsat 5: 30m resolution• Landsat 5 image of Gloucestershire  (Landsat 6 crashed on take off. Landsat 7  is current satel...
Ikonos: 1m resolution• Commercial panchromatic image at 1m resolution.  On the original image people can be seen walking i...
Ikonos agricultural image 1m resolution• Another Ikonos image showing the detail available in  an agricultural image, here...
RADARSAT classified image of Flevoland, NL• Radar, “active remote sensing”, sees through clouds  and in the dark. This add...
RADARSAT-Mozambique floods• Shuttle borne radar image of the Mozambique floods• Radar is good at detecting the edge of wat...
Remote sensing summary• Aerial photography gives us a controllable,  highly detailed view of the Earth• Satellite imagery ...
Satellite and aerial surveys
Satellite and aerial surveys
Upcoming SlideShare
Loading in...5
×

Satellite and aerial surveys

2,847

Published on

Published in: Education, Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
2,847
On Slideshare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
0
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Satellite and aerial surveys

  1. 1. Data capture from above:GPS and remote sensing Global positioning systems Aerial photography Satellite imagery
  2. 2. Global positioning system (GPS)• Current system run by USA military• Gives normal accuracy of ~5m• European alternative called Galileo under construction• Systems use satellites to allow users to calculate their position in the Earth
  3. 3. Global Positioning Systems (GPS) satellite based navigation • 24 satellites in orbit, 21 functioning at any time • Each broadcasts its ID, the time and its orbital position • The user receives this data and calculates the receiver’s position in relation to the satellite • If the receiver can pick up signals from at least 4 satellites, it can calculate its position on the Earth’s surface
  4. 4. Important points to note about GPS• The satellites transmit data which is picked up by the user’s receiver on the ground• Nothing is transmitted from the user to the satellite• GPS only gives your geographical position in real time, it does not create images or maps
  5. 5. Satnav• GPS tells you where you are now• Satnav unit has built in digital maps• GPS position is displayed on the map• Satnav unit then calculates the route from current position to destination
  6. 6. GPS based yield mapping at the RAC GPS satellitesGPS data:location of yield samples Yield Map smart card Yield data: t/ha at each sample point
  7. 7. Mapping yield levelsYield class maps for sixadjoining plots. The yielddata, shown in colour, comesfrom the yield meter, all theGPS tells you is the locationof the yield samples lowest yield highest yield 1993
  8. 8. Examples of data collection: GPS data collection Mobile GPS and data recorder Weed patch centroids, extent and species
  9. 9. Examples of GPS use by US Geological survey
  10. 10. Remote sensing what is it?• Observation from a distance – Aerial photographs- very detailed – Satellite images – global view
  11. 11. Oblique aerial photograph• Viewed from an oblique angle: looking sideways• Looks natural, easy to understand, useless for measurement purposes
  12. 12. Vertical aerial photograph• Viewed straight down giving a “map view”• Difficult to understand at first. Can be used as a basis of mapping, after image has been rectified
  13. 13. Aerial photographs: 1995 and 1972
  14. 14. Map derived form aerial photographs• Visible features are “digitised” by tracing around them on a computer screen.• This creates the points lines and polygon symbols which build up into the map
  15. 15. Stereo-photography 3-d visualisation• Overlapping aerial photographs can be used to build 3-d stereoscopic visual models. These can be used to map out contours and heights of features Photo 1 Photo 2 Plane travels at constant altitude above sea level. Height above ground varies with topography overlap 60% of image
  16. 16. Stereoscopic reconstruction of overlapping areas• A stereoscope is used to view the overlapping areas simultaneously and the brain builds a 3-d model of the landscape where the images overlap. Right eye Left eye Photo 1 Photo 2 overlap
  17. 17. Digital manipulation of aerial photographs• 3-d models can also be built by “digitally draping” photographs over a digital elevation model of the landscape.
  18. 18. Sources of aerial photographs• UK aerial photography is available on-line, or can be commissioned• www.getmapping.com is one source
  19. 19. Satellite Remote Sensing• Satellites give a higher viewpoint and give unrestricted coverage of the whole globe Link to Gateway Remote sensing video http://gateway.rac.ac.uk/mod/resource/view.php?id=3937
  20. 20. Satellite orbits• Geostationary orbit: above the equator, 35,000 km height, orbital period 24 hours. Satellites appear fixed in sky• Low Earth orbit, usually polar, orbital period can be less than 1 hour. Satellites seen to move across sky
  21. 21. Geo-stationary meteorological satellite: Meteosat• Geostationary orbits, approx 33,000 km elevation over the equator. Satellite takes 24hours for one orbit, the earth rotates once in that time, so the satellite appears stationary in the sky Infra-red image from 0600 March 8, 2000 “Ground” position of satellite
  22. 22. Polar orbiting meteorological satellites• Polar orbiting satellites cover the whole globe, but move, so there are long time intervals between one image and the satellites next return
  23. 23. Earth observation satellites: Landsat 7 image (30m resolution)• Earth observation satellites are designed to view the surface of the globe. Some are designed for view the oceans, others, like the Landsat series, observe the land
  24. 24. 2004 tsunami: Aceh province, Sumatra
  25. 25. 2004 tsunami: Aceh province, Sumatra
  26. 26. Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to classify landcover.• The reflectance of certain landcover types are measured on each image to build up a signature of that type of cover. This is then searched for over the whole image
  27. 27. Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to classify landcover.• The reflectance of certain landcover types are measured on each image to build up a signature of that type of cover. This is then searched for over the whole image
  28. 28. Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to classify landcover.• The reflectance of certain landcover types are measured on each image to build up a signature of that type of cover. This is then searched for over the whole image
  29. 29. Land classification; spectral signatures: Using SPOT images• Simultaneous Multi-spectral images can be used to classify landcover.• The reflectance of certain landcover types are measured on each image to build up a signature of that type of cover. This is then searched for over the whole image
  30. 30. Remote sensing images:Harnhill farm
  31. 31. Aerial photograph, 2011Spatial resolution approx. 0.2m
  32. 32. GoogleMaps aerial photo,Spatial resolution approx. 1.5m
  33. 33. Scanned Aerial photograph, 1995Spatial resolution approx. 2.0m
  34. 34. Landsat 5 image, circa 2001Spatial resolution approx. 30m
  35. 35. LIDAR image, 2011Spatial resolution approx. 1.0mVertical resolution approx. 0.001m
  36. 36. Landsat 5: 30m resolution• Landsat 5 image of Gloucestershire (Landsat 6 crashed on take off. Landsat 7 is current satellite) Cheltenham Gloucester Harnhill Swindon
  37. 37. Ikonos: 1m resolution• Commercial panchromatic image at 1m resolution. On the original image people can be seen walking in Horse Guards Parade and the spokes of the London Eye are visible
  38. 38. Ikonos agricultural image 1m resolution• Another Ikonos image showing the detail available in an agricultural image, here form Montana• How useful is this for farmers?
  39. 39. RADARSAT classified image of Flevoland, NL• Radar, “active remote sensing”, sees through clouds and in the dark. This addresses some of the major problems with “Passive remote sensing” which measures reflected sunlight.• The images are very difficult to interpret
  40. 40. RADARSAT-Mozambique floods• Shuttle borne radar image of the Mozambique floods• Radar is good at detecting the edge of water bodies, which it can “see” through cloud cover
  41. 41. Remote sensing summary• Aerial photography gives us a controllable, highly detailed view of the Earth• Satellite imagery gives global, unrestricted views which are repeated a frequent intervals• The references to actions such as “interpretation” and “classification” lead on to things we can do with a geographic information system (GIS) using remote sensing as a source of data

×