REMOTE SENSING

1
REMOTE SENSING GIS (Chapter 12) A Path to a
Job!

• OUR TOPICS
• A Bit of Introduction to Remote Sensing
• Aerial Photography / Photogrammetry
• Earth Resource Satellites
• Geographic Information Systems (GIS)

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REMOTE SENSING Intro

• Study of objects from a distance, e.g.
• Human sight, smell, hearing
• Use of electromagnetic energy (usually UV to
  radio wavelengths)
• Instruments in aircraft or spacecraft
• In forestry, aerial photography has been most
  important type

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SPECTRAL RESPONSE PATTERNS

• Reflectance/absorbency of various wavelengths
  (see Fig. 12.10)
• Different objects have different patterns
• Specific wavelengths are suitable for specific
  objects of interest, e.g.
• Deciduous vs. coniferous B/W IR
• Plants under stress 0.7 - 1.3 um

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AERIAL PHOTOGRAPHY Advantages

• Efficient
• Extensive coverage
• Works well for remote treacherous terrain
• Began in 1930s (cameras hot air balloons)

5
AERIAL PHOTOGRAPHY Allows 3-D Images

• Photographs taken at regular intervals along
  flight lines (see Fig. 12.12)
• If endlap gt 50 ? stereoscopic coverage of
  entire area
• Stereo pairs two views of objects ? 3-D image

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See Figs. 11.6 12.12
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AERIAL PHOTOGRAPHY Scale

• One distance unit on photo represents specific
  ground distance, . . . but . . .
• Scale depends on flight altitude above objects
• Therefore objects on one photo are not all in
  same scale
• Also . . . objects tops are displaced from bases
• So . . . cant use photos directly as maps

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PHOTOGRAMMETRY Definition

• Interpretation of aerial photos, e.g.
• Ground distance direction
• Land area (e.g., of forest stands)
• Heights of objects (e.g., trees)
• Construction of topographic maps
• Terrain elevations slopes (contour lines)
• Terrain shapes (ridges, valleys)
• Water flow directions
• http//terraserver.microsoft.com

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PHOTOGRAMMETRYBasis

• Based on image characteristics, e.g.
• Shape size (including height)
• Pattern
• Tone (hue)
• Texture (e.g., to ID tree species)
• Shadows (e.g., to ID tree species)
• Site (e.g., to determine possible species)
• Association (e.g., clearcuts roads)

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PHOTOGRAMMETRYFrom Photos to Maps

• Digital Orthophotograph (Digital Ortho Quad
  (DOQ))
• modern technology applied to stereo photo pairs
• digital image with benefits of both maps and
  photographs
• visible features
• constant scale across the image
• DOQs can be integrated into GIS analyses

11
PHOTOGRAMMETRY Photo Mensuration

• Photo mensuration yields measures of, e.g.
• Stand area
• Stand density
• Tree height
• Crown diameter
• Photo volume tables are possible

12
PHOTOGRAMMETRY Additional Applications

• Forestland appraisal
• Harvest planning
• Monitoring
• Logging reforestation
• Herbicide fertilizer applications
• Wildlife habitats
• Forest health assessment (diseases insects, air
  pollution, fuel loads and fire effects, frost,
  moisture stress, soil salinity, nutrient
  imbalance, storm effects, soil erosion, etc.)

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EARTH RESOURCE SATELLITES

• Several spectral bands available this permits
  ID of cover type
• Resolution to 10 meters or better
• Repeated viewing of an area
• Trends over time
• Stereoscopic data
• Useful?

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GEOGRAPHIC INFORMATION SYSTEMS (GIS)

• Computer-based systems for spatial data
• GIS data stored in layers, e.g.
• Elevation
• Soils
• Cover type
• Ownership
• GIS is essential for Forestry NRC graduates --
  you should take a course!

15
GIS Benefits

• Maps updated quickly accurately
• Effects of land management activities can be
  modeled before implementation
• Inter-agency cooperation
• Available at desktop user friendly!

16
GIS Spatial Analysis

• Database Operations
• Sorting, searching, and selecting
• Compound searches (Queries)
• E.g., Select aspen stands greater than 80 acres
  over 40 years of age
• Arithmetic and Statistical Functions
• E.g., Stand volume calculated from tree diameter,
  tree height, and stand area information contained
  in GIS

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GIS Spatial Analysis

• Geographic Operations
• E.g., create buffers
• E.g., identify conflicting land uses

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GIS Vector and Raster Databases
See Fig. 12.3
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GIS Digitizing

• On-Screen
• Easy
• Comfortable
• Accurate
• Powerful
• Backups easy
• Cheap

• Automatic
• Quick
• Great for people who would rather have a machine
  do it for you!

Scan Point Click Walk away
Scan Point Click, Click, Click, Click, Click,
Click, Click, Click, Click, Click, Click,
Click, Click, Click . . .
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GIS Digitizing
This is going to take a long time!

• The Old School (Stone Tablets)
• Tedious
• Very slow
• Error-prone
• Limited power
• Backups costly
• Expensive in labor

http//office.microsoft.com/clipart/