3S技术在水利工程中的应用遥感.pptx

Remote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsRemote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsDefinitions of Remote SensingCan be very general,e.g.“The acquisition of physical data of an object without touch or contact”(Lintz and Simonett,1976)“The observation of a target by a device some distance away”(Barrett and Curtis,1982)Remote Sensing 遥感遥感Definitions of Remote SensingCan be very general,e.g.“The acquisition of physical data of an object without touch or contact”(Lintz and Simonett,1976)“The observation of a target by a device some distance away”(Barrett and Curtis,1982)Remote Sensing 遥感遥感Definitions of Remote SensingOr more specific,e.g.“The use of electromagnetic radiation sensors to record images of the environment,which can be interpreted to yield useful information”(Curran,1985)Remote Sensing 遥感遥感Definitions of Remote SensingOr more specific,e.g.“The use of electromagnetic radiation sensors to record images of the environment,which can be interpreted to yield useful information”(Curran,1985)Remote Sensing 遥感遥感Definitions of Remote SensingOr more specific,e.g.“The use of sensors,normally operating at wavelengths from the visible to the microwave,to collect information about the Earths atmosphere,oceans,land and ice surfaces”(Harris,1987)Remote Sensing 遥感遥感Definitions of Remote SensingOr more specific,e.g.“The use of sensors,normally operating at wavelengths from the visible to the microwave,to collect information about the Earths atmosphere,oceans,land and ice surfaces”(Harris,1987)Remote Sensing 遥感遥感Remote Sensing 遥感遥感Definitions of Remote Sensing遥远感知事物。不直接接触目标物，在距离地物一定距离的地方，使用遥感器接受地面物体发射或发射的电磁波信号，记录并传送到地面，经过信息处理、判读分析和野外实地验证，最终形成影象供用户使用。Definitions of Remote SensingMain characteristics Physical separation between sensor and target Medium=electromagnetic radiation(sonar is an exception)Device to sample and measure radiation(sensor)Target is the terrestrial environment(atmosphere,oceans,land surface)Remote Sensing 遥感遥感Physical separation between sensor and targetMedium=electromagnetic radiation(sonar is an exception)Device to sample and measure radiation(sensor)Target is the terrestrial environment(atmosphere,oceans,land surface)Remote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsThe natural environment isextremely complexhighly variable(space and time)complicated further by human actionRemote Sensing 遥感遥感History of Remote SensingNormally,we experience our world while living on its surface from a more or less horizontal viewpoint.But,under these conditions our view is usually limited to areas of a few square miles at most owing to obstructions such as buildings,trees,and topography.The total area encompassed in our vistas is considerably enlarged if we peer downward from,say,a tall building or a mountain top.Remote Sensing 遥感遥感History of Remote SensingHistory of Remote SensingRemote sensing began with aerial photographyRemote Sensing 遥感遥感History of Remote Sensing First photographs taken in 1839Remote Sensing 遥感遥感History of Remote Sensing1858 Gasper Felix Tournachon Nadar takes photograph of village of Petit Bicetre in France from a balloonRemote Sensing 遥感遥感Paris by Nadar,circa 1859Remote Sensing 遥感遥感Boston by Black and King(1860)Remote Sensing 遥感遥感Remote Sensing 遥感遥感the most novel platform at the beginning of the 20th century was the famed Bavarian pigeon fleet that operated in Europe.History of Remote SensingPigeons at the ready are shown here,with a famed 1903 picture taken of a Bavarian castleRemote Sensing 遥感遥感Remote Sensing 遥感遥感History of Remote Sensing1903 first plane made by Wright brothers1909 First photos from an aeroplaneWorld War One was a major impetus to development of aerial photographyAfter the war the technology was in place to begin large scale aerial surveysRemote Sensing 遥感遥感The Soviet Union surprised the world when they launched Sputnik,the worlds first satellite,on October 4,1957 Explorer-1 was the first successful U.S.earth satellite launched on January 31,1958(123 days after Sputnik-1)TIROS-1(Television Infrared Observation Satellite)was the first weather satellite launched on April 1,1960TIROS 1 paved the way for generations of weather satellitesExplorer-1TIROS-1Remote Sensing 遥感遥感TIROS-1 versus GOES-8Stark contrast between first TIROS image and the full-color full-Earth image that GOES-8 produces today.Remote Sensing 遥感遥感Remote Sensing 遥感遥感1970年年4月月24日，日，中国第一颗人中国第一颗人造卫星造卫星“东方红东方红1号号”成功上天，成功上天，成为继苏联、美国、法国和日本成为继苏联、美国、法国和日本之后第五个发射卫星的国家。之后第五个发射卫星的国家。History of Remote SensingRemote Sensing 遥感遥感1972 the first LANDSAT was launchedHistory of Remote Sensing1991 the first terrestrial radar satellite1986 the first commercial French satellite SPOT became operationalRemote Sensing 遥感遥感History of Remote SensingRemote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsTypes of aerial photograph（空中摄影，航空摄影）（空中摄影，航空摄影）Vertical Low oblique High obliqueRemote Sensing 遥感遥感Types of aerial photograph Vertical Low oblique(no horizon)High obliqueRemote Sensing 遥感遥感Types of aerial photograph Vertical Low oblique High obliqueRemote Sensing 遥感遥感Types of aerial photographVertical is most importantas it has minimum distortion and can be used for taking measurementsRemote Sensing 遥感遥感Types of aerial photographFiducialmarksRemote Sensing 遥感遥感Types of aerial photographFiducialaxesRemote Sensing 遥感遥感Types of aerial photographPrincipalpointMarginalinformationRemote Sensing 遥感遥感Types of aerial photographAn aerial photograph mission will be flown in strips,shutter timing set for 60%endlap(needed for parallax)and strips spaced for 30%sidelap(to avoid missing bits)Remote Sensing 遥感遥感Types of aerial photograph Endlap(or forelap)is the important bit It ensures every point on the ground appears in at least two photographsRemote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsRemote Sensing 遥感遥感Photogrammetry（摄影测量）（摄影测量）If you know focal length of camera and height of aircraft above the ground you can calculate the scale of the photographRemote Sensing 遥感遥感PhotogrammetryScale=f/（H-h）f=focal length(distance from centre of lens to film surface)Remote Sensing 遥感遥感PhotogrammetryScale=f/(H-h)H=flying height of aircraft above sea levelh=height of groundabove sea levelRemote Sensing 遥感遥感PhotogrammetryWhen you know the scale you can take 2-D measurements from a photograph(e.g.horizontal distance,horizontalarea,etc.)Remote Sensing 遥感遥感PhotogrammetryBut to take“true”measurements on an uneven surface you needto work in 3-DRemote Sensing 遥感遥感PhotogrammetryBut to take“true”measurements on an uneven surface you needto work in 3-DYou can dothis thanks toparallaxRemote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsRemote Sensing 遥感遥感Parallax（视差）（视差）Pencil is very displaced because it is close to observerChurch is less displaced because it is further awayRemote Sensing 遥感遥感Remote Sensing 遥感遥感Parallax（视差）（视差）Two fundamental aspects of stereoscopic parallax are:1.the parallax of any point is directly related to the elevation of that point;2.the parallax is greater for higher than lower elevations provided the viewing angle is constant.These two relationships allow height measurements to be made from a stereo pair.ParallaxThe same principle can be used to find height of objects in stereopairs of vertical aerial photographsRemote Sensing 遥感遥感Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax ConclusionsRemote Sensing 遥感遥感Conclusions Remote sensing involves collecting information about the Earth from a distance using electromagnetic sensors It evolved from aerial photography Vertical stereopairs of aerial photographs are used to take 3-D measurements by measuring parallaxRemote Sensing 遥感遥感