ESRM 304: Environmental and Resource Assessment © Phil Hurvitz, 2009 KEEP THIS TEXT BOX this slide...

ESRM 304: Environmental and Resource Assessment

© Phil Hurvitz, 2009

ESRM 304Autumn 2009Phil Hurvitz

Modern Methods ofMapping, Navigation, and

Analysis

1 of 42



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

2 of 42

Ad hoc, ad loc, and quid pro quo. So little time, so much to know



What is a map (remember from last class session?)

What makes a map what it is?

[Discussion]

Mapping

3 of 42



Why, in a modern/quantitative sense, are these not maps?

What is a (not) map?

4 of 42

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



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?


5 of 42

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



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)


6 of 42

Don’t get “Lost in Space”

Use GPS and GIS!



MappingGIS: it’s more than just pretty maps

(much more)Where y’at? Everything you ever

wanted to know about GPS

Overview

7 of 42



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

8 of 42



Why is GIS important in natural resource management?

[Discussion]

GIS

9 of 42



Why is GIS important in natural resource management?

It allows (relatively) easy, quantifiable, repeatable, and standardized measurements of the landscape and

its features.

GIS

10 of 42



MappingGIS: it’s more than just pretty maps

(much more)Where y’at? Everything you ever

wanted to know about GPS

Overview

11 of 42



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

(e.g., GIS, forest inventory) 12 of 42



Measurement methods

Q: How do we solve the problems with traditional measurement methods?

A: GPS and GIS

13 of 42



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

14 of 42




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

15 of 42




Requires careful measurement, training

Equipment is “self-recording” Does not require external data recording

Field notebooks are not necessary

Does not require specialized training No mathematics “1 or 2 day” training

16 of 42




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

17 of 42




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

18 of 42



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)


19 of 42




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)

20 of 42



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

21 of 42



History of the GPS

22 of 42



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 min

TIMATION I (USN, 1967) Coded signals Precise timing Ranging based on transit time of signal

23 of 42



History of the GPS

Navigation Technology Program(USN, USAF, 1973)

Evolved to NAVSTAR GPS Phase I (1973-78)

Concept validation Prototype satellites

24 of 42



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?

25 of 42



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

26 of 42



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

27 of 42



How does GPS work?

With the distance from 1 satellite we can locate our position on the surface of a sphere

28 of 42



How does GPS work?

With the distance from 2 satellites we can locate our position on the intersection of 2 spheres (a circle)

29 of 42



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)

30 of 42



How does GPS work?

With the distance from 4 satellites we can locate our position on the intersection of 4 spheres (1 point)

31 of 42



How does GPS work?

The point is (hopfully) located on the surface of the earth

32 of 42



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!

33 of 42



Potential GPS error sources

Satellite geometrySatellites that are closer result in less

accurate measurements

34 of 42




Satellite geometryA large spread of satellites makes the

most accurate measurements

35 of 42




Landscape features

Natural & artificial features can intercept signals

Mountains, valleys, hills, buildings, tree canopies, etc.

36 of 42




Multipath errors

Natural & artificial features can reflect signals

Multiple “ghost” signals can confound timing: which signal to trust?

37 of 42



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

38 of 42



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

39 of 42



Different measurement methods exist Metes & bounds Plane surveying Geodetic surveying GPS

Different data storage systems exist Maps Paper or electronic tabular records GIS

Conclusion

40 of 42



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

41 of 42



“The earth has music for those who listen.”— William Shakespeare

To Infinity and Beyond

42 of 42

ESRM 304: Environmental and Resource Assessment © Phil Hurvitz, 2009 KEEP THIS TEXT BOX this slide...

Documents

Transcript of ESRM 304: Environmental and Resource Assessment © Phil Hurvitz, 2009 KEEP THIS TEXT BOX this slide...