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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
ESRM 304Autumn 2009Phil Hurvitz
Modern Methods ofMapping, Navigation, and
Analysis
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Mapping (again!??)GIS: it’s (much) more than just pretty
mapsWhere y’at? Everything you ever
wanted to know about GPS*
*but were afraid to ask
Overview
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Ad hoc, ad loc, and quid pro quo. So little time, so much to know
ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
What is a map (remember from last class session?)
What makes a map what it is?
[Discussion]
Mapping
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Why, in a modern/quantitative sense, are these not maps?
What is a (not) map?
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Archaeologists have discovered what they believe is the earliest known map, dating from almost 14,000 years ago. (in Spain)
A Neo-Babylonian (Persian Period, circa 500 BCE) copy of an original map dating to the Sargonid Period, circa late eighth or seventh century BCE
ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Why, in a modern/quantitative sense, are these not maps?
Short answer: Lack of sufficient control/standardization of
location of any particular feature (you could get lost easily)
Lack of regular measurement framework (how will new features be placed on the map in the proper location?
What is a (not) map?
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Archaeologists have discovered what they believe is the earliest known map, dating from almost 14,000 years ago. (in Spain)
A Neo-Babylonian (Persian Period, circa 500 BCE) copy of an original map dating to the Sargonid Period, circa late eighth or seventh century BCE
ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
What really is a map (in a modern, quantitative sense)?
Short answer: a series of controlled, carefully structured X, Y, Z, M coordinates
Where X, Y, Z come from surveying (or some variation) in a standardized measurement framework, and matrix M comes from another measurement domain (e.g., soil type, forest stand species composition)
What is a (not) map?
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Don’t get “Lost in Space”
Use GPS and GIS!
ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
MappingGIS: it’s more than just pretty maps
(much more)Where y’at? Everything you ever
wanted to know about GPS
Overview
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
What does GIS do?1. [Fundamentally important]: stores
XYZM coordinates in a standardized digital framework a land records database on steroids
2. Allows fine control over the display of these coordinates a mapping function
3. [Ultimately important]: allows geometric and logical processing of XYZM data to support decision-making
GIS
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Why is GIS important in natural resource management?
[Discussion]
GIS
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Why is GIS important in natural resource management?
It allows (relatively) easy, quantifiable, repeatable, and standardized measurements of the landscape and
its features.
GIS
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
MappingGIS: it’s more than just pretty maps
(much more)Where y’at? Everything you ever
wanted to know about GPS
Overview
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Measurement methods
Problems with traditional natural resource location measuring systems
Not always accurate or repeatable Requires careful measurement, training Requires careful note taking Can take large amounts of time Data storage issues
Field notebooks Difficult-ish integration with other data
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Measurement methods
Q: How do we solve the problems with traditional measurement methods?
A: GPS and GIS
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS solve these problems?
Manual measurements are not always accurate
GPS brings accuracy 12 m accuracy for typical “camping” grade
GPS equipment 1 m for mapping grade equipment Sub-centimeter accuracy for high-grade
equipment Measurement of mountain building Measurement of plate tectonics
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS solve these problems?
Manual measurements are not always repeatable
If you can get to the location (e.g., tree, inventory plot marker), your measurement will be repeatable within the precision of the equipment
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS solve these problems?
Requires careful measurement, training
Equipment is “self-recording” Does not require external data recording
Field notebooks are not necessaryDoes not require specialized training No mathematics “1 or 2 day” training
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ESRM 304: Environmental and Resource Assessment
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How does GPS solve these problems?
Requires careful note taking
Equipment frequently contains digital data logger
Locational and informational data are stored digitally in the data logger
Field notebooks are not necessary
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ESRM 304: Environmental and Resource Assessment
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How does GPS solve these problems?
Takes large amounts of time
Measuring lines (e.g., roads, trails) is as fast as walking or driving
Measuring polygons (e.g., stands, treatment units) is as fast as walking
Measuring point locations can be as fast as stopping and pushing a few buttons
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Data storage issues
Data are stored digitally; transferred digitally
Data backup and transfer on magnetic, solid state, or optical disk (fast, cheap, easy)
Standard computer equipment (CD, external hard drive, flash memory)
How does GPS solve these problems?
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS solve these problems?
Integration with other data (e.g., GIS, inventory)
GPS data are already in digital format Easily used in association with other digital
methods Inventory systems (e.g., FLIPS, SuperAce) GIS (direct export from GPS to GIS formats)
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
History of the GPS
Cold War origins Advances in missile technology, 1940s-80s
Advances in missile navigation systems (silo-to-silo attacks)
Submarine missile launchers Missile launches need precise coordinates Surfaced submarines need fast locational
fix Fire a missile quickly to avoid being seen
Need for locational technology that is fast and precise
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
History of the GPS
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ESRM 304: Environmental and Resource Assessment
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History of the GPS
Evolved out of EM/radio wave locational technologies (WWII onward)
TRANSIT (US Navy, Polaris 1964) Public access, 1967 Doppler shift of satellite as it moved Stationary fix, ~every 40 minTIMATION I (USN, 1967) Coded signals Precise timing Ranging based on transit time of signal
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History of the GPS
Navigation Technology Program(USN, USAF, 1973)
Evolved to NAVSTAR GPS Phase I (1973-78)
Concept validation Prototype satellites
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ESRM 304: Environmental and Resource Assessment
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History of the GPS
Navigation Technology Program(USN, USAF, 1973)
Evolved to NAVSTAR GPS Phase II (1978)
Full-scale development 4 satellites launched By 1985, 7 operational satellites, ~5 hrs coverage Current = 32 satellites
Others? GLONASS: Russian Federation (1984-
Present) EU? Japan? Commercial vendors?
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How does GPS work?
Satellite signals Satellites send coded radio wave signals Signals are stamped with particular data:
Time of signal generation Satellite ID number
Radio waves are a form of EM radiation Light travels at 186,000 mi/s (in a vacuum)Time stamps on signals result in
distance measurements
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ESRM 304: Environmental and Resource Assessment
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How does GPS work?
Distance = rate * time Radio waves are sent from orbiting
satellites Time stamp on each signal marks the start
of the wave Time of reception marks the end of the
wave
start: 0.00 s
end: 0.06 s 12,000 mi
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS work?
With the distance from 1 satellite we can locate our position on the surface of a sphere
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS work?
With the distance from 2 satellites we can locate our position on the intersection of 2 spheres (a circle)
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS work?
With the distance from 3 satellites we can locate our position on the intersection of 3 spheres (1 of 2 points)
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS work?
With the distance from 4 satellites we can locate our position on the intersection of 4 spheres (1 point)
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
How does GPS work?
The point is (hopfully) located on the surface of the earth
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
What are the benefits of GPS vs. manual survey?
Summary: benefits of GPS over other methods
Easy to learn Fast to use Automated data recording Requires less attention to detail Errors are not additive No math!
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Potential GPS error sources
Satellite geometrySatellites that are closer result in less
accurate measurements
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Potential GPS error sources
Satellite geometryA large spread of satellites makes the
most accurate measurements
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Potential GPS error sources
Landscape featuresNatural & artificial features can
intercept signals
Mountains, valleys, hills, buildings, tree canopies, etc.
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Potential GPS error sources
Multipath errorsNatural & artificial features can reflect
signals
Multiple “ghost” signals can confound timing: which signal to trust?
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Equipment can fail, resulting in lost or corrupted data
Equipment can be misconfigured, leading to lost or corrupted data, or in the best circumstance, correctable systematic error
The DoD could go brokeYou could go broke (and not be able to
buy a GPS unit)
Other potential GPS problems
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Land measurement and navigation systems have evolved over time
Throughout the “modern” history of measurement, standards have been critical
Many different measurement frameworks exist
Metes & bounds PLSS UTM State Plane …
Conclusion
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
Different measurement methods exist Metes & bounds Plane surveying Geodetic surveying GPSDifferent data storage systems exist Maps Paper or electronic tabular records GIS
Conclusion
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
No measurement framework, method, or storage system is perfect
Different methods are the most appropriate in different situations
Considerations: Functional requirements Cost Ease of use Institutional considerations
Conclusion
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ESRM 304: Environmental and Resource Assessment
© Phil Hurvitz, 2009
“The earth has music for those who listen.”— William Shakespeare
To Infinity and Beyond
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