S技术在水利工程中的应用-遥感.ppt

Remote Sensing遥感,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Definitions of Remote Sensing,Can 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,Definitions of Remote Sensing,Can 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,Definitions of Remote Sensing,Or 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,Definitions of Remote Sensing,Or 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,Definitions of Remote Sensing,Or 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,Definitions of Remote Sensing,Or 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,Remote Sensing 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 Sensing,Main 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,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,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,The natural environment isextremely complexhighly variable(space and time)complicated further by human action,Remote Sensing 遥感,History of Remote Sensing,Normally,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,History of Remote Sensing,History of Remote Sensing,Remote sensing began with aerial photography,Remote Sensing 遥感,History of Remote Sensing,First photographs taken in 1839,Remote Sensing 遥感,History of Remote Sensing,1858 Gasper Felix Tournachon Nadar takes photograph of village of Petit Bicetre in France from a balloon,Remote Sensing 遥感,Paris by Nadar,circa 1859,Remote Sensing 遥感,Boston by Black and King(1860),Remote Sensing 遥感,Remote Sensing 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 Sensing,Pigeons at the ready are shown here,with a famed 1903 picture taken of a Bavarian castle,Remote Sensing 遥感,Remote Sensing 遥感,History of Remote Sensing,1903 first plane made by Wright brothers,1909 First photos from an aeroplane,World War One was a major impetus to development of aerial photography,After the war the technology was in place to begin large scale aerial surveys,Remote Sensing 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 satellites,Explorer-1,TIROS-1,Remote Sensing 遥感,TIROS-1 versus GOES-8,Stark contrast between first TIROS image and the full-color full-Earth image that GOES-8 produces today.,Remote Sensing 遥感,Remote Sensing 遥感,1970年4月24日，中国第一颗人造卫星“东方红1号”成功上天，成为继苏联、美国、法国和日本之后第五个发射卫星的国家。,History of Remote Sensing,Remote Sensing 遥感,1972 the first LANDSAT was launched,History of Remote Sensing,1991 the first terrestrial radar satellite,1986 the first commercial French satellite SPOT became operational,Remote Sensing 遥感,History of Remote Sensing,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Types of aerial photograph（空中摄影，航空摄影）Vertical Low oblique High oblique,Remote Sensing 遥感,Types of aerial photograph Vertical Low oblique(no horizon)High oblique,Remote Sensing 遥感,Types of aerial photograph Vertical Low oblique High oblique,Remote Sensing 遥感,Types of aerial photographVertical is most importantas it has minimum distortion and can be used for taking measurements,Remote Sensing 遥感,Types of aerial photograph,Fiducialmarks,Remote Sensing 遥感,Types of aerial photograph,Fiducialaxes,Remote Sensing 遥感,Types of aerial photograph,Principalpoint,Marginalinformation,Remote Sensing 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,Types of aerial photograph Endlap(or forelap)is the important bit It ensures every point on the ground appears in at least two photographs,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Remote Sensing 遥感,Photogrammetry（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 photograph,Remote Sensing 遥感,PhotogrammetryScale=f/（H-h）f=focal length(distance from centre of lens to film surface),Remote Sensing 遥感,PhotogrammetryScale=f/(H-h)H=flying height of aircraft above sea levelh=height of groundabove sea level,Remote Sensing 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,PhotogrammetryBut to take“true”measurements on an uneven surface you needto work in 3-D,Remote Sensing 遥感,PhotogrammetryBut to take“true”measurements on an uneven surface you needto work in 3-DYou can dothis thanks toparallax,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Remote Sensing 遥感,Parallax（视差）,Pencil is very displaced because it is close to observerChurch is less displaced because it is further away,Remote Sensing 遥感,Remote Sensing 遥感,Parallax（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.,Parallax,The same principle can be used to find height of objects in stereopairs of vertical aerial photographs,Remote Sensing 遥感,Structure Definitions of Remote Sensing History of remote sensing Types of aerial photograph Photogrammetry Parallax Conclusions,Remote Sensing 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 parallax,Remote Sensing 遥感,