Title: Data in GIS: Remote Sensing Prof' Carolyn Merry Dept' of Civil
1Data in GISRemote Sensing Prof. Carolyn
MerryDept. of Civil Environmental Engineering
Geodetic ScienceCollege of Engineeringmerry.
1_at_osu.edu
2Definition of Remote Sensing
- "Remote sensing is the practice of deriving
information about the earth's land and water
surfaces using images acquired from an overhead
perspective, using electromagnetic radiation in
one or more regions of the electromagnetic
spectrum, reflected or emitted from the earths
surface. (Campbell, 1996)
3(No Transcript)
4Platforms Used toAcquire Remote Sensing Data
- Aircraft
- Low, medium high altitude
- Higher level of spatial detail
- Satellite
- Polar-orbiting, sun-synchronous
- 800-900 km altitude, 90-100 minutes/orbit
- Geo-synchronous
- 35,900 km altitude, 24 hrs/orbit
- stationary relative to Earth
5(No Transcript)
6(No Transcript)
7Electromagnetic Spectrum
- Remote sensing images are taken within specific
spectral regions
8TM 4 near IR
TM 2 green
9SPOT band 3 near IR
SPOT band 1 green
10Spectral Reflectance Curve
- Distinctive spectral response patterns for earth
surface features
High
Vegetation
Soil
Spectral Reflectance
Water
Low
Blue Green Red Near IR
Mid IR
Spectral Region
11Electromagnetic Radiation
- Passive remote sensing
- reflected radiation UV, visible, NIR, MIR
- emitted radiation thermal IR
- depends on external energy source, Sun
- Active remote sensing
- energy transmitted from remote sensing platform,
use reflected energy to form an image - manmade radiation (microwave band of wavelengths
imaging radars) - operate at night during cloudy weather
12What is a digital image?
Source NASA Observatorium
13Remote Sensing Digital Images
- Scanned aerial photographs
- Digital cameras
- Video images
- Satellite images
- Radar images
14Advantages of Remote Sensing Data
- Remote sensing data may be more current
- Map a large variety of themes from one image
- Users can interpret remote sensing imagery
- Images cover large areas in one snapshot
15Image Resolution
- Spatial
- Refers to pixel size of image
- Images with small ground pixel sizes are of high
spatial resolution - Landsat-7 30 m vs. Ikonos 4 m
16OSU Campus
Landsat-7 ETM 30-m
Ikonos 4-m
17Image Resolution (contd)
- Spectral resolution
- Band width recorded by the remote sensing image
- Narrower the wavelength band, the better the
spectral resolution
18Landsat Multispectral Scanner (MSS)
- 79-m (82-m) resolution for 4 bands
- Band 1 - Green 0.5-0.6 mm
- Band 2 - Red 0.6-0.7 mm
- Band 3 - Near infrared 0.7-0.8 mm
- Band 4 - Near infrared 0.8-1.1 mm
19Spectral Band Coverage for the Landsat Thematic
Mapper 30-m resolution
20Image Resolution (contd)
- Temporal resolution
- How frequently the image is acquired
- AVHRR daily coverage vs. Landsat TM every 16 days
- Radiometric resolution
- Number of reflectance values that can be recorded
- AVHRR 210 (1024 gray levels) data vs. Landsat TM
28 (256 gray levels) data
21Historical Archive
Landsat 5, 1984
Landsat 5, 1989
Landsat 5, 1994
Landsat 7, 1999
DISP, 1962
22Satellite Imagery
23Newest Satellite Imagery
- Landsat-7 ETM (April, 99)
- 7 multispectral bands (30-m resolution, 60-m
thermal band) - 15-m panchromatic band
- IKONOS-1 (September, 99)
- 1-m pan, 4-m multispectral (4 bands)
- Quickbird (October, 01)
- 0.6 m pan, 2.5-m multispectral (4 bands)
24Landsat-7 coverage over Ohio
25Landsat-7 ETM 30-m XS
26Landsat-7 ETM 15-m pan
27DLG files
28ETM
Ikonos
DEM
29Cedar Point, Ohio
30IKONOS 4-m Olympic Park Sydney, Australia
31Statue of Liberty 60-cm natural
color QuickBird 2 Aug 02
32How to Use Remote Sensing Data
- Process satellite imagery using image processing
methods - geometric corrections are made
- classification imported into GIS
- register to GIS coordinate system
- Enter as raw image data
- use as backdrop for vector data
33Spectral pattern recognition
Source Canadian Center for Remote Sensing
34Geometric registration process
Image-to-map registration
Source Canadian Center for Remote Sensing
35Using Remote Sensing Data (contd)
- Manual interpretation of aerial photographs
- Interpret the imagery identify features draw
boundaries - Produce a map or set of maps
- Need to correct for geometric errors
- Boundaries digitized imported into GIS
36Typical Data Sets DerivedFrom Remote Sensing Data
- Land use/land cover maps, particularly changes in
land use/land cover - Elevation
- Temperature
- Biomass estimates
- Vegetation types
37Digitize Aerial Photoswith Stereoplotters
- Aerial photos registered to selected reference
coordinate system vertical datum - Orient stereoplotter to ground control points
(GCPs) before digitizing - Digitize planimetric features when viewing the
3-D stereomodel - DEM read automatically from created 3-D
stereomodel
38Why is Elevation So Important?
- Elevation contours digitize critical points
along contours - Software used to derive triangular irregular
network (TIN) - TIN used to derive point elevations, profiles,
cross-sections, slopes, aspects, contours at
any interval
39Using Topographic Data
- Calculate shortest path or most navigable path
over a mountain range to construct road, route or
transmission line - Assess visibility from various lookout points or
along roads - Simulate travel through landscape
- Create aspect slope layers generate shaded
relief images - Provide data layer to use with satellite image
classification GIS modeling
40Pan image laser elevations plotted as intensity
Courtesy of EarthData Technologies
41Digital Orthophotographs
- Planimetrically corrected aerial photograph
(effects of relief tilt displacements are
removed) - USGS - quadrangle-based with 4 images per
7.5-minute quad - Projected into UTM system - 1 m pixel size - 28
bit data
42On-line tutorials in remote sensing
- Fundamentals of remote sensing - CCRS
- http//www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/f
undam/fundam_e.html - NASA remote sensing tutorial
- http//rst.gsfc.nasa.gov/start.html
- Remote sensing core curriculum
- http//research.umbc.edu/tbenja1/umbc7/
43Uses of Remote Sensing (from Cracknell Hayes,
1991)