1. Photogrammetry and Multispectral Remote Sensing Lecture 3 September 8, 2004

2. 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

3. Types of vantage points to acquire photographs  Vertical vantage points  Low-oblique vantage points  High-oblique vantage points

4. Gooseneck s of the San Juan River in Utah Gooseneck s of the San Juan River in Utah Vertical Aerial Photography Jensen, 2000 Most are vertical aerial photography

5. Low-oblique photograph of a bridge on the Congaree River near Columbia, SC. Low-oblique photograph of a bridge on the Congaree River near Columbia, SC. Low-oblique Aerial Photography Jensen, 2000

6. High-oblique photograph of the grand Coulee Dam in Washington in 1940 High-oblique Aerial Photography Jensen, 2000

7. 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

8. 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)

9. 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.

10. Flightline of Vertical Aerial Photography Jensen, 2000

11. Block of Vertical Aerial Photography Jensen, 2000

12. Block of Vertical Aerial Photography Compiled into an Uncontrolled Photomosaic Jensen, 2000 Columbia, SC Original scale = 1:6,000 Focal length = 6” (152.82 mm) March 30, 1993 Columbia, SC Original scale = 1:6,000 Focal length = 6” (152.82 mm) March 30, 1993

13. Scale of photographs  Image size/ real world size : S = ab/AB  Focal length/ altitude above ground: S = f / H

14. Scale (2) 1’ = 12 ” 0.012/ (6 x 12) = 1/6000 S = f / (H-h) Max scale, minimum scale, and average or nominal scale

15. 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.

16. Extraction of Building Infrastructure based on orthophotographs

17. Orthophotograph draped over a DEM

18. Kevin Hankinson will share his experience in acquiring aerial photos

19. 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.

20. Overview Overview Jensen, 2000 Energy detected is recorded as an analog electrical signal

21. Remote Sensing Raster (Matrix) Data Format Remote Sensing Raster (Matrix) Data Format Jensen, 2000 Y axis

22. Jensen, 2000 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

23. 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 mirrors Liner arrays and area arrays

24. Jensen, 2000 Landsat satellite series MSS TM ETM+ 0.5-0.6 0.45-0.52 0.45-0.52 0.6-0.7 0.52-0.60 0.52-0.61 0.7-0.8 0.63-0.69 0.63-0.69 0.8-1.1 0.76-0.90 0.78-0.90 10.4-12.6 1.55-1.75 1.55-1.75 10.4-12.5 10.4-12.5 2.08-2.35 2.09-2.35 0.52-0.90 79m 30 30 240m 120 60 15 6 bits 8 8 103 m/c 99 99 18 days 16 16 919km 705 705 185km 185 185

25. Inclination (99º) of the Landsat Orbit to Maintain A Sun-synchronous Orbit Inclination (99º) of the Landsat Orbit to Maintain A Sun-synchronous Orbit Jensen, 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 99º TM 98.2º

26. Today’s Landsat 7 orbits and acquisition http://landsat7.usgs.gov/pathrows.php

27. TexasView Remote Sensing Consortium http://www.texasview.org/pages/archives/html/landsat.html Free Landsat 7 imagery available from TexasView

28. About the lab setup and a DEMO of ENVI