Introducing GIS and Remote Sensing

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Introducing GIS and Remote Sensing

• Introduction to Mapping and GIS

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Rowan University
Think about all the activity occurring though out
a landscape. How can we map, manage and analyze
all that is going on? GIS!
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US Census Data in Excel
Think about keeping information about phenomenon
on a landscape. How could you do it?
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US Census Data in GIS
GIS organizes that data with a map. But GIS is
much more.
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Data Types
Aspatial datadata not tied to a location on the
earths surface
Spatial datadata associated with a location on
earth Much of the information we deal with daily
has some spatial component.
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What is GIS?

• Data Management -
• Manages various kinds of GIS data including
  vector, raster, images, tables, other data files
• Data models and architectures
• Conversion between formats
• Import/export utilities
• Interacts with RDBMS (SQL Server, Oracle, etc)

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What is GIS?

• Analysis
• Spatially aware data
• Attribute and spatial query
• Proximity and Overlay
• Advanced geoprocessing techniques
• Decision support
• Flexible, customization
• Programming, scripting (to perform analysis)

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What is GIS?

• Visualization
• Maps! Maps! Maps!
• If a picture is worth a 1000 words
• Professional cartographic tool
• Charts, graphs, tables, etc
• Various coordinate systems
• 2D and 3D
• Web, desktop, handheld, etc

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What is GIS?

• Data Management Database View
• Analysis Model View
• Visualization Map View

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G vs. IS

• GIS uses maps to spatially analyze and search for
  patterns in the data that would otherwise not be
  found. (Content)
• GIS stores, manipulates, and displays data files
  and relationships in a information system using
  standard computing practices. (IT)
• With advances in technology, GIS users must now
  deal with both aspects!

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The G

• G Geographic
• Denotes the concept of spatial location on
  Earths surface
• Importance of relative location (not just where
  you are but where you are in relation to
  everything else)
• Theories and techniques in Geography form the
  basis of GIS

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The I

• I Information
• Substance (knowledge) about location
• Factual and interpretative
• Tables Maps Analysis
• Transformation of table information into spatial
  context for analysis
• Technology and computer systems

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What about just GI?

• Yes, it is used quite often.
• Commonly used as a replacement for or broadening
  of the term GIS data
• But

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What About the S in GIS?

• Systems
• Science
• Studies
• Services

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Geospatial?

• Geographic GIS Geospatial
• Move in recent years to better define the
  industry and to focus on data (business) over
  geographic principles (academic)
• Geospatial includes all subcomponents of GIS
  embedded in other areas (remote sensing, GPS etc.)

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Not Just Computer Cartography
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Core of GIS Layers
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Importance of Layers in GIS

• Geographic data Representation of reality
• Reality is complex.
• GIS utilizes a layer approach
• Each layer only includes information about one
  type of phenomenon.
• Data layers must be aligned with one another

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Importance of Layers

• Proximity
• Finding what is near or within a distance from a
  certain location or feature
• e.g., all houses within 100 yards of a stream
• Overlay
• Combining two layers to create new information
• e.g., habitat based on veg, elevation, and temp

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Families of GIS Data (1)

• Vector mode or coordinate based
• Three vector objects existpoints, lines,
  polygons these are called features.
• They are represented by X,Y coordinates
• sometimes Z (3D), sometimes M (linear reference)
• Information about features is (are) called
  attributes.
• Two types of vector modelstopological and object
• Topological means the data models stores
  relationships between vectors
• Vector objects exist independent of any other
  nearby features

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Families of GIS Data (2)

• Raster mode or grid cell
• Entire study area is covered by a grid
• Each cell within grid is given a value
• Values can be integer or decimal
• Data can be discrete or continuous
• Cell size is variable and linked to the file size
  of the raster data
• Areas outside of the grid are ignored
• Grid must be expanded if those areas are to be
  included

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Modeling Geospatial Reality
Raster Model
Vector Model
Real World
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Coding Vector GIS
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Coding Vector GIS
Vector Mode Model of Reality
Reality
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Coding Raster GIS Data
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Coding Raster GIS Data
1 1 1 1 2 3 4 4 1 1 1 2 2
3 4 4 1 2 2 2 3 3 4 4 2 2
2 3 3 4 4 4 3 3 3 3 5 5
5 5 1 1 1 1 6 5 5 5 1 1 1
1 1 5 5 5 1 1 1 1 1 1 5 5
Raster Mode Model of Reality
Reality
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Advantages of Vector

• Vector data make maps that look more like maps we
  are use to seeing on paper.
• The shapes of features are accurately
  represented.
• Vector data can have TOPOLOGY
• Vector data is good for managing attributes
• Vector data can have smaller dataset
• Only the objects need to be represented in the
  database (empty space in-between is not captured)
• Vector

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Disadvantages of Vector

• Complicated data structure
• Software must manage many data tables
• Not good at representing geographic features that
  gradually change over location
• For example elevation or moisture in soil
• Slower processing time

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Advantages of Raster

• Good at depicting continuously changing surfaces
  such as elevation or soil moisture
• Grid format is simple data structure
• Easier for computer to make analytical
  calculations
• Ideal for utilizing remote sensing images

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Disadvantages of Raster

• Maps can be blocky looking (depending on the size
  of the grid cells)
• Cells can only be coded for one attribute when
  there may be more than one attribute at each
  location
• Can have very large datasets (depending on the
  size of the grid cell)
• Is NOT TOPOLOGICAL data structure

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Remote Sensing

• Remotely-Sensed data is one of the most important
  sources of data for GIS.
• RS means - Acquiring data from a distance
• Usually uses electromagnetic energy
• sunlight, radar, laser
• Originally captured on photographic film
• Recent platforms utilize digital sensors

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Early Remote Sensing Platforms
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What kinds of devices collect the data?

• Aircraft
• High altitude
• Low altitude
• Spacecraft
• Landsat
• SPOT
• Weather satellites
• GeoEye-1

Geosynchronous Orbitwhen the satellite moves at
the same speed as the spinning earth results in
the camera staying over the same spot of the earth
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Aircraft Images
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• Black and Whiteor
• Panchromatic
• Sensitive to visible light

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Digital Orothographic Photos

• Digital photos of the earth
• Usually acquired by aircraft
• Orthographic means that the photo has all
  distortion removed
• A regular photo from an airplane will have
  distortion due to
• Parallax effect that distance away from the
  center point of a photo will always have
  distortion
• Terrain the hills and valleys or a land area
  will cause distortion in the photo
• An orthographic photo is adjusted by computer
  software to make the image line up with a flat
  map

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Digital OIrthographic Photo-quad Infrared
You are here
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Remote Sensing Mediums

• Black and White or Panchromatic
• Sensitive to visible light
• True Color
• Similar to color film
• Infrared
• Sensitive to infrared frequencies that cant be
  seen by humans
• Developed by military for identifying tanks
  painted with camouflage
• Good for evaluating conditions of vegetation
• Good for evaluating moisture in soil
• False-color adjusted
• When frequencies of received data are shifted to
  allow or enhanced human viewing
• Multi spectral
• When more than a single band of energy is
  captured
• Color is multi-spectral (3 bands)
• Some satellites can have 7 or even more bands
  of sensitivity

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The Electromagnetic Spectrum
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The Visible Spectrum

• The visible spectrum is only a tiny window
• We are blind to 99.99 of the energy in the
  universe
• We have created devices that allow us to see
  beyond the range of human vision

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Satellite Images

• Weather satellite image Winter in North America.

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What are the spatial units for which data are
collected?

• Pixel or Picture Element
• Smallest unit of data collection
• Features smaller than the pixel size cant be
  distinguished
• Pixel Sizes
• Landsat MSS 79 meters
• Landsat TM 30 meters
• SPOT 10 meters
• IKONOS 1 meter
• GeoEye-1 0.41 meters

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Spatialresolutionkeeps gettingbetter...
GeoEye-1
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1, 3, and10 meters
Spatial resolution keeps getting better...
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Temporal Resolution

• Remote sensing images begin to get old as soon as
  they are taken
• Satellites repeatedly circle the earth
• Airplanes must be commissioned every time they
  photograph (expensive).
• NJ aerial photography was taken 1995, 2002, and
  2007.
• Statewide aerials often have to be taken in
  multiple years (95/97) (07/08)

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What is GIS?

• Now that weve learned the essential elements
  that make up a GIS
• and have seen examples of how GIS is being used
• lets take a look at the big picture.

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GIS Is Evolving
Systems
Networks
Projects
Integrated
Coordinated
Cooperative
. . . Moving to the Internet and Web Services
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How is GIS used?

• Sometimes, the best way to learn about GIS is to
  see how its being used..
• Science
• Emergency management
• Government record-keeping
• Business location
• Environmental management
• Planning
• Crime mapping

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Creating a Digital Earth
Measuring and Integrating Spatial and Thematic
Information
. . . A Nervous System for Spaceship Earth
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Violence in Darfur

• Image shows 2004 2006.
• Area too large and dangerous for small
  peacekeeping force.
• Violence tracked using satellite images.
• Article.

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California Wildfires

• LA Times and local residents are mapping the
  spread of major wildfires.
• Using web-based GIS to present and catalog data.
• Article.

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GeoCommons

• GeoCommons is a "mashup" maker
• Upload your data excel or GIS and have it
  mapped
• Find data others have shared
• Make maps, then export to Google Earth