S技术在水利工程中的应用遥感课件

1、S技术在水利工程中的应用遥感Remote Sensing遥 感S技术在水利工程中的应用遥感Remote SensingLast Lecture Absorption features Vegetation Soils Rocks and minerals Water, ice and snow ConclusionsS技术在水利工程中的应用遥感Last Lecture EMR which has interacted with matter will be deficient in some wavelengths, due to absorption processes occurring

2、at atomic or molecular scales These absorption features create distinctive “spectral signatures” for different Earth surface types These can be exploited by “multispectral” remote sensing methods for mapping and monitoring purposesRemote SensingS技术在水利工程中的应用遥感Spectral SignaturesRemote SensingS技术在水利工程

3、中的应用遥感Remote Sensing地表任一点反射的电磁波被分解为若干地表任一点反射的电磁波被分解为若干个波段，每个波段有一个反射率个波段，每个波段有一个反射率S技术在水利工程中的应用遥感Remote Sensing反射率的大小用灰度表示，并被转换成反射率的大小用灰度表示，并被转换成数字信号，通常是数字信号，通常是28（0-255）S技术在水利工程中的应用遥感504030201000.40.60.70.81.3REFLECTANCE(%)Wavelength (micrometers)Visible0.5Near IRGrassGREENBLUEGREENREDBLUEGREENREDNE

4、AR IRNear IRS技术在水利工程中的应用遥感Band PlacementWavelength, mLandsat TMRGB1005002575Percent ReflectanceNear IRMid IR0.40.60.81.01.21.41.61.82.02.22.42.6Silty-clay soilTurbid river waterVegetationClear river waterMuck soil1 23457visible1 234MSIIKONOS & HI RESPANLANDSAT 7 PANS技术在水利工程中的应用遥感Band DisplayBand 1Ba

5、nd 2Band 3Band 4Band 5Band 7BLUEGREENREDNEAR IRSHORTWAVE IRMID-WAVE IRNEAR IRS技术在水利工程中的应用遥感Color Theory All colors created from additive primary colors: Red Green Blue Complementary colors: Magenta CyanRedGreenBlueMCYWBlackS技术在水利工程中的应用遥感Multispectral DisplayBLUEGREENREDNEAR IRSHORTWAVE IRMID-WAVE IR

6、LONGWAVE IR1Landsat TM Band234576Band Combination =742 (LANDSAT)Color Guns =Band Composite Output =S技术在水利工程中的应用遥感Band 3Visible RedBand 2Visible GreenBand 1Visible BlueIndividual Landsat BandsApplied to Color GunsResulting ImageS技术在水利工程中的应用遥感Band 4Near InfraredBand 3Visible RedBand 2Visible GreenIndi

7、vidual Landsat BandsApplied to Color GunsResulting ImageS技术在水利工程中的应用遥感AVRIS Hyperspectral CubeS技术在水利工程中的应用遥感SensingSensor arrayLens225214199198202176 Each “cell” recorded as a “digital number” (DN) or “brightness value” Measures amount of EM radiation The brighter the signal, the higher the value.S技

8、术在水利工程中的应用遥感PixelsEach cell is called a “picture element”, or pixelEach pixel represents a single brightness value for a specific geographical area225 204 188 146214 198 169 152202 200 178 162i columnsj rowsi x j = 4 x 4 = 16 pixels114 109 101 97S技术在水利工程中的应用遥感Sensor Properties Spatial resolution Spe

9、ctral resolution/# bands Radiometric resolution Temporal resolutionSource: NASAS技术在水利工程中的应用遥感Spatial Resolution Measure of the smallest angular or linear separation between 2 objects that can be resolved by the sensor In practice, sensor systems nominal spatial resolution is the dimension in meters

10、(or feet) on the ground projected instantaneous field of view (IFOV) Generally, smaller spatial resolution greater the resolving power of the sensor systemS技术在水利工程中的应用遥感S技术在水利工程中的应用遥感Spatial ResolutionIKONOS4mLandsat30mDOQ0.5m Space ImagingS技术在水利工程中的应用遥感(cont.) Spatial ResolutionUseful rule: To dete

11、ct a feature, the spatial resolution of the sensor system should be less than the size of the feature measured in its smallest dimension.S技术在水利工程中的应用遥感Spectral ResolutionNumber and size of the bands which can be recorded by the sensor nominal spectral resolution Coarse sensitive to large portion of

12、ems contained in a small number of wide bands Fine sensitive to same portion of ems but have many small bandsGoal finer spectral sampling to distinguish between scene objects and featuresMore detailed information about how individual features reflect or emit em energy increase probability of finding

13、 unique characteristics that enable a feature to be distinguished from other features.S技术在水利工程中的应用遥感Spectral Resolution the SPECTRAL resolution defines the range of light stored in the image A black and white photograph stores a visible light; it has one channel that stores the light for 0.4 to 0.7

14、micrometers A natural color image stores reflected red, blue and green light in different channels; e.g. 0.45 - 0.52 m for blue, 0.52 - 0.60 m for green and 0.63 - 0.69 m for red A LANDSAT image contains 7 channnels as described above that store reflected light other than visible light. A HYPER-SPEC

15、TRAL image contains hundreds of channels. E.g. A hyperspectral image that collects visible light may divide the visible light range into 300 channels, each channel containing a narrow range of wavelengths. S技术在水利工程中的应用遥感Spectral Resolution/# Bands100s of BandsHyper-spectralNIRSWIRLW IRSWIRBand 2.53-

16、.62Band 3.63-.69 Band 1.45-.52VisibleBand 4.79-.90Band 51.55-1.75Band 72.08-2.35Band 610.4-12.4Near IRSWIRLWIR1000s of BandsUltra-spectralMulti-spectralS技术在水利工程中的应用遥感Spectral Resolution/# Bands504030201000.40.60.70.81.3ConcreteREFLECTANCE(%)Wavelength (micrometers)GrassVisible0.5GREENBLUEGREENREDNea

17、r IRS技术在水利工程中的应用遥感S技术在水利工程中的应用遥感Radiometric Resolution the RADIOMETRIC resolution defines the range of values that an individual pixel can have Refers to the sensitivity of the sensor to incoming radiance. Typical digital images have a range of values from 0 255 (a total of 256 possible values). An

18、image that just has black or white pixels would only store 0 (black) or 1 (white). RADAR images have range from 0 to 4.3 x 109. S技术在水利工程中的应用遥感Radiometric ResolutionThe ability of a sensor to perceive differences in brightness value levels22or 4 intensity levels28or 256 intensity levels32112003232112

19、0032Sensor “A”Sensor “B”22519072124137630255 141S技术在水利工程中的应用遥感Temporal Resolution How often the remote sensing system records imagery of a particular area.Examples Landsat 18 days SPOT 26 daysS技术在水利工程中的应用遥感Temporal Resolution2752 Km at the Equator185 KmOrbit 1, Day 1Orbit 2, Day 1Orbit 1, Day 8Orbit 2, Day 8LandsatS技术在水利工程中的应用遥感Trade-OffsAerial PhotoIKONOSLandsatSpatial Resolution m4m30m# Bands1