GEOGRAPHY CLUB MEETING

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GEOGRAPHY CLUB MEETING

• Where 2nd Floor of Library in Seminar Room.
• When Thursday, Sept. 24th 2009 4-5pm.
• Who All students are welcome! Even if you cant
  make the whole meeting, come for a while.
• What Executive positions will be decided.
  Information on future events.
• If you cannot make this meeting and want to be
  involved or run for an executive position please
  email Jesse at blewettj_at_unbc.ca

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Data downloaded from geogratis.ca
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Since 1945, all our topographic mapping is done
from aerial photography Air photos enabled a
huge reduction in fieldwork costs, and an
increase in how quickly and accurately large
areas could be mapped
Athabasca Glacier, 1958
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Early days Boston, from Tethered Balloon
(1860) Development of air photography before
airplanes
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Modern photography from kites Alaska
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From balloon, launched by students in
Massachusetts, September 2, 2009
Total cost (weather) balloon, camera (from
eBay), cooler, and hand warmers lt 130
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Word War I Air photos for reconnaisance from
fighter planes and pigeons
Balloons and kites were easy to shoot down, but
pigeons were not. Small light weight cameras were
attached to the birds and a timer was set to take
pictures ever 30 seconds as it flew
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Oblique photos from mountain peaks Banff
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Early topographic mapping from mountain peaks
Canadian Rockies, 1888
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Photogrammetry       "the science of obtaining
reliable measurements from photos" Photo
interpretation "the identification and
extraction of meaning of objects"
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Anaglyphs the two photos are superimosed, one in
red, one in blue together we see in 3D
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Once corrected, and georeferenced, photos can be
used for topographic mapping and as a GIS mapping
layer, with  map data overlain on top. A
photograph that has been corrected and is
'planimetrically correct' is known as an 
orthophoto (e.g. as in google maps or imap ).
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Provincial photography is generally redone about
every 10 years City photography more frequently
3-5 years PG 2006
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PG 2003
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PG 1997
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Image interpretation
http//airphotos.nrcan.gc.ca/photos101/photos101_i
nfo_e.php
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Shape the form of an object on an air photo
helps to identify the object. Regular uniform
shapes often indicate a human involvement
Pattern similar to shape, the spatial
arrangement of objects (e.g. row crops vs.
pasture) is also useful to identify an object and
its usage
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Shadow a shadow provides information about the
object's height, shape, and orientation (e.g.
tree species)
Texture the physical characteristics of an
object will change how they appear on a photo
(e.g. calm water has a smooth texture a forest
canopy has a rough texture)
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Size a measure of the object's surface area
(e.g. single-lane vs. multi-lane highways)
Time temporal characteristics of a series of
photographs can be helpful in determining the
historical change of an area (e.g. looking at a
series of photos of a city taken in different
years can help determine the growth of suburban
neighbourhoods
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Association/Site associating the presence of one
object with another, or relating it to its
environment, can help identify the object (e.g.
industrial buildings often have access to railway
sidings
Tone/Colour the colour characteristics of an
object, relative to other objects in the photo
(e.g. sand has a bright tone, while water usually
has a dark tone tree species can be determined
by the colour of their leaves at certain times of
the year)
Monochrome (panchromatic) air photos are used
more frequently as colour  photography costs
twice as much.
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Google maps (and Earth)and other online mapping
These contain satellite image mosaics (not
photographs) .. and aerial photograph mosaics
(after zoom in)
http//maps.google.ca
Digital photography The majority of aerial
photos still use film, but that these are then
scanned and input into 'softcopy' digital
photogrammetric software for processing.
Digital cameras approach the resolution of
film, but have a smaller footprint
Digital photos Terrasaurus, Williams Lake
http//terrasaurus.ca/terrasaurus/about.html