Photogrammetry and Multispectral Remote Sensing Lecture 3 September 8, 2004.
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Transcript of Photogrammetry and Multispectral Remote Sensing Lecture 3 September 8, 2004.
Photogrammetry and Multispectral Remote Sensing
Lecture 3
September 8, 2004
What is Photogrammetry
Photogrammetry is the art and science of making accurate measurements by means of aerial photography: Analog photogrammetry (hard-copy photos) Digital photogrammetry (digital images)
Aerial photographs were the first form of remote sensing imagery.
Differences between photogrammetry and Remote Sensing are that photographs are: Black and white (1 band) or color (blue, green, red, and IR) Wavelength range of 0.3-1.0 m Use cameras One type of remote sensing imagery
Types of vantage points to acquire photographs
Vertical vantage points Low-oblique vantage points High-oblique vantage points
GooseneckGoosenecks of the s of the
San Juan San Juan River River in Utahin Utah
GooseneckGoosenecks of the s of the
San Juan San Juan River River in Utahin Utah
Vertical Aerial PhotographyVertical Aerial PhotographyVertical Aerial PhotographyVertical Aerial Photography
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Altitude above-ground- level (AGL)
Vertical Aerial Photograph Over
Level Terrain
Principal point (PP)
Optical axis
Camera film plane
field of view
Altitude above-ground- level (AGL)
Vertical Aerial Photograph Over
Level Terrain
Principal point (PP)
Optical axis
Camera film plane
field of view
Most are vertical aerial photography
Low-oblique photograph of a bridge Low-oblique photograph of a bridge on on
the Congaree River near Columbia, the Congaree River near Columbia, SC.SC.
Low-oblique photograph of a bridge Low-oblique photograph of a bridge on on
the Congaree River near Columbia, the Congaree River near Columbia, SC.SC.
Low-oblique Aerial PhotographyLow-oblique Aerial PhotographyLow-oblique Aerial PhotographyLow-oblique Aerial Photography
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Low-Oblique Aerial Photograph Over
Flat Terrain
Horizon is not shown in photograph
Optical axis
field of view
Low-Oblique Aerial Photograph Over
Flat Terrain
Horizon is not shown in photograph
Optical axis
field of view
High-oblique photograph of the High-oblique photograph of the grand Coulee Dam in Washington grand Coulee Dam in Washington
in 1940in 1940
High-oblique photograph of the High-oblique photograph of the grand Coulee Dam in Washington grand Coulee Dam in Washington
in 1940in 1940
High-oblique Aerial PhotographyHigh-oblique Aerial PhotographyHigh-oblique Aerial PhotographyHigh-oblique Aerial Photography
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
High-Oblique Aerial Photograph Over
Flat Terrain
Horizon is shown in the photographOptical
axis
field of view
High-Oblique Aerial Photograph Over
Flat Terrain
Horizon is shown in the photographOptical
axis
field of view
Color Science
Additive primary colors : Blue, Green, and Red
Subtractive primary colors (or complementary colors): Yellow, Magenta, and Cyan
Filters (subtract or absorb some colors before the light reaches the camera): Red filter (absorbs green and blue, you can
red) Yellow (or minus-blue) filter (absorbs
blue, allows green and red to be transmitted, which is yellow)
Haze filter (absorbs UV)
additive
Subtractive
Types of photographs
Black and white photographs Panchromatic (minus-blue filter used to eliminate UV and blue
wavelengths) IR (IR-sensitive film and IR only filter used to acquire photographs at
0.7- 1.0 m ) UV (at 0.3-0.4 m, low contrast and poor spatial resolution due to
serious atmospheric scattering) Color photographs
Normal color (Haze filter used to absorb UV and create true color 0.4-0.7 m, or blue, green, red)
IR color (Yellow filter used to eliminate blue and create IR color of 05-1.0 m, or green, red, IR)
4 bands (blue, green, red, and IR)
Satellite photographs
Extensive collections of photographs have been acquired from manned and unmanned Earth or Mars-orbiting satellites. Beginning in 1962, USA acquired photographs of moon for Apollo
mission 1995, USA declassified intelligence satellites photographs of Sino-
Soviet acquired 1960-1972 at 2-8 m resolution. 2000, Russia launched satellites acquired photographs of 2 meter
resolution 1999, Mars Global Surveyor of NASA acquires Mars photographs
with 1.2 – 12 m resolution 2003, Mars Express of ESA acquires Mars photographs with 2 and
10 m resolution.
Flightline of Vertical Aerial Photography Flightline of Vertical Aerial Photography Flightline of Vertical Aerial Photography Flightline of Vertical Aerial Photography
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Exposure station #1
stereoscopic model
#2 #3
Direction of Flight
terrain recorded on three successive photographs
lens altitude above ground level, H
60% overlap
Coverage of photograph
Flightline of Aerial Photography
Exposure station #1
stereoscopic model
#2 #3
Direction of Flight
terrain recorded on three successive photographs
lens altitude above ground level, H
60% overlap
Coverage of photograph
Flightline of Aerial Photography
Block of Vertical Aerial Photography Block of Vertical Aerial Photography Block of Vertical Aerial Photography Block of Vertical Aerial Photography
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
20 – 30% sidelap
oblique photography may be acquired at the end of a flightline as the aircraft
banks to turn
Flightline #3
Flightline #2
Block of Aerial Photography
Flightline #1
20 – 30% sidelap
oblique photography may be acquired at the end of a flightline as the aircraft
banks to turn
Flightline #3
Flightline #2
Block of Aerial Photography
Flightline #1
Block of Vertical Block of Vertical Aerial Photography Aerial Photography Compiled into an Compiled into an
Uncontrolled Uncontrolled Photomosaic Photomosaic
Block of Vertical Block of Vertical Aerial Photography Aerial Photography Compiled into an Compiled into an
Uncontrolled Uncontrolled Photomosaic Photomosaic
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
4-44-54-6
3-63-53-4
Block of Aerial Photography
Compiled into an Uncontrolled
Photomosaic
a.
b.
4-44-54-6
3-63-53-4
Block of Aerial Photography
Compiled into an Uncontrolled
Photomosaic
a.
b.
Columbia, SCColumbia, SCOriginal scale = 1:6,000Original scale = 1:6,000Focal length = 6” (152.82 Focal length = 6” (152.82
mm)mm)March 30, 1993 March 30, 1993
Columbia, SCColumbia, SCOriginal scale = 1:6,000Original scale = 1:6,000Focal length = 6” (152.82 Focal length = 6” (152.82
mm)mm)March 30, 1993 March 30, 1993
Scale of photographs
Principal Point
Optical axis
Camera lens
Focal length, f
A B
a b
o
P
Positive print
Real-world object space
Image space
Altitude above ground level,
H
Exposure Station, L
Principal Point
Optical axis
Camera lens
Focal length, f
A B
a b
o
P
Positive print
Real-world object space
Image space
Altitude above ground level,
H
Exposure Station, L
Image size/ real world size : S = ab/AB
Focal length/ altitude above ground: S = f / H
Scale (2)
56.1’
0.113”
6’
0.012”
56.1’
0.113”
6’
0.012”
1’ = 12 ”
0.012/ (6 x 12) = 1/6000
Average elevation above sea level,
h
Camera lens
Focal length f
Exposure station, L
A B
e go
P
Sea level
C
D
Highest elevation above sea level,
h max
Lowest elevation above sea level,
hmin
c d
Altitude above
sea level H
E
G
a bImage space
Object space
Average elevation above sea level,
h
Camera lens
Focal length f
Exposure station, L
A B
e go
P
Sea level
C
D
Highest elevation above sea level,
h max
Lowest elevation above sea level,
hmin
c d
Altitude above
sea level H
E
G
a bImage space
Object space
S = f / (H-h)
Max scale, minimum scale, and average or nominal scale
Orthophotographs and digital orthoimagery
Photograph after corrected by ground control points (x, y, z) or digital elevation model (DEM) called orthophotograph, orthophoto, or digital orthoimagery.
Not as photographs, they have different scales in different terrain relief, orthophotos have only one scale, no distortion, and have true distance, angle, and area. Orthophotos can be directly input into GIS as basemap or for interpretation.
Extraction of Building Infrastructure based on orthophotographs
Extraction of Building Infrastructure based on orthophotographs
Orthophotograph draped over a DEMOrthophotograph draped over a DEM
Kevin Hankinson will share his experience in acquiring aerial
photos
Multispectral Remote Sensing
Multispectral remote sensing is defined as the collection of reflected, emitted, or backscattered energy from an object or area of interest in multiple bands of electromagnetic spectrum; while Hyperspectral remote sensing involves data collection in hundreds of bands.
Instead of cameras and 1 or 4 bands for photogrammetry, Remote sensing use detectors that are sensitive to hundreds of bands in the electromagnetic spectrum. Measurements made by detectors are always stored in a digital format.
Overview Overview Overview Overview
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Energy detected is recorded as an analog electrical signal
Remote Sensing Raster (Matrix) Data FormatRemote Sensing Raster (Matrix) Data Format Remote Sensing Raster (Matrix) Data FormatRemote Sensing Raster (Matrix) Data Format
0
127
255
Brightness value range
(typically 8 bit)Associated gray-scale
10 15 17 20
15 16 18 21
17 18
20
22
18
20
22 24
1
2
3
4
1 5432Columns ( j)
Bands (k )
1
2
3
4
X axis Picture element (pixel) at location Line 4, Column 4, in Band 1 has a Brightness Value of 24, i.e., BV4,4,1 = 24 .
black
gray
white21
23
22
25
Lines or rows (i)
0
127
255
Brightness value range
(typically 8 bit)Associated gray-scale
10 15 17 20
15 16 18 21
17 18
20
22
18
20
22 24
1
2
3
4
1 5432Columns ( j)
Bands (k )
1
2
3
4
X axis Picture element (pixel) at location Line 4, Column 4, in Band 1 has a Brightness Value of 24, i.e., BV4,4,1 = 24 .
black
gray
white21
23
22
25
Lines or rows (i)
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Y axis
Jensen, 2000Jensen, 2000
Scanning Mirror
and Discrete Detectors
Lens
Scan mirror
Linear Array “pushbroom”
Objective
b.
Dispersing element
Lens
Collimator
Slit
Objective
Hyperspectral Area Array
d.
a.
c.
Linear Array “whiskbroom” Dispersing
elementLens
Collimator
Objective aperture
Scan mirror
Blue
NIRBlue
NIR
e.
Lens and filtration
Digital Frame Camera Area
Arrays
Detectors (multiple arrays)
Detectors
Scanning Mirror
and Discrete Detectors
Lens
Scan mirror
Linear Array “pushbroom”
Objective
b.
Dispersing element
Lens
Collimator
Slit
Objective
Hyperspectral Area Array
d.
a.
c.
Linear Array “whiskbroom” Dispersing
elementLens
Collimator
Objective aperture
Scan mirror
Blue
NIRBlue
NIR
e.
Lens and filtration
Digital Frame Camera Area
Arrays
Detectors (multiple arrays)
Detectors
Detector configurations: breaking ou the spectrum
Discrete Detectors and scanning mirrors
- MSS, TM, ETM+, GOES, AVHRR, SeaWiFS, AMS, ATLAS
Linear Arrays
- SPOT, IRS, IKONOS, ORBIMAGE, Quickbird, ASTER, MISR
Liner and area arrays
- AVIRIS, CASI, MODIS, ALI, Hyperion, LAC
Field of View (FOV), Instantaneous Field of View (IFOV)Dwell time is the time required for the detector IFOV to sweep across a ground cell. The longer dwell time allows more energy to impinge on the detector, which creates a stronger signal.
Sabin, 1997
Discrete Detectors and scanning mirrorsLiner arrays and area arrays
Jensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Landsat satellite series
MSS TM ETM+0.5-0.6 0.45-0.52 0.45-0.520.6-0.7 0.52-0.60 0.52-0.610.7-0.8 0.63-0.69 0.63-0.690.8-1.1 0.76-0.90 0.78-0.9010.4-12.6 1.55-1.75 1.55-1.75 10.4-12.5 10.4-12.5 2.08-2.35 2.09-2.35 0.52-0.9079m 30 30240m 120 60 156 bits 8 8103 m/c 99 9918 days 16 16 919km 705 705185km 185 185
Inclination (99º) of the Landsat Orbit to Inclination (99º) of the Landsat Orbit to Maintain A Sun-synchronous OrbitMaintain A Sun-synchronous Orbit
Inclination (99º) of the Landsat Orbit to Inclination (99º) of the Landsat Orbit to Maintain A Sun-synchronous OrbitMaintain A Sun-synchronous Orbit
99Þ
Landsat at 12:30 p.m. local time
Equatorial plane and
direction of Earth
rotation
Landsat at 9:42 a.m. local time
N
S
99Þ
Landsat at 12:30 p.m. local time
Equatorial plane and
direction of Earth
rotation
Landsat at 9:42 a.m. local time
N
SJensen, 2000Jensen, 2000Jensen, 2000Jensen, 2000
Sun-synchronous orbit mean that the orbital plane precessed around Earth at the same angular rate at which Earth moved around the Sun
The satellite cross the equator at approximately the same local time (9:30 to 10:00 am)
MSS 99ºTM 98.2º
Today’s Landsat 7 orbits and acquisition
http://landsat7.usgs.gov/pathrows.php
TexasView Remote Sensing Consortium
http://www.texasview.org/pages/archives/html/landsat.html
Free Landsat 7 imagery available from TexasView
About the lab setup and a DEMO of ENVI