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Photogrammetry
 

Photogrammetry

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This is only about to konow what is photogrammetry not detialed imformation

This is only about to konow what is photogrammetry not detialed imformation

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Photogrammetry Photogrammetry Presentation Transcript

  • PHOTOGRAMMETRY G.CHANDRA SEKHAR REDDY M.Tech(GIS) NIIT UNIVERSITY
  •  VERY PRECISE 3D REPRESENTATION TIME EFFECTIVE COST EFFECTIVE BASED ON WELL ESTABLISHED AND TESTED ALGORITHMS LESS MANUAL EFFORT MORE GEOGRAPHIC FIDELITY
  •  Photos – light Gramma – to draw Metron – to measure “Photogrammetry is the technique of measuring objects from photographs” “The art, science and technology of obtaining reliable spatial information about physical objects and the environment through the processes of recording, measuring and interpreting image data”
  •  Aerial photography is the taking of photographs of the ground from an elevated position. The term usually refers to images in which the camera is not supported by a ground-based structure Close-range Photogrammetry the camera is close to the subject and is typically hand held or on a tripod
  • PROCESS FLOW RAW DATA FORM CLIENT (SCANS) AERIAL TRIANGULATION DATA CAPTURING DEM GENARATION CONTOUR GENARATION ORTHOPHOTO GENARATION
  •  In Aerial Photogrammetry the camera is mounted in an aircraft and is usually pointed vertically towards the ground Multiple overlapping photos of the ground are taken as the aircraft flies along a flight path These photos are processed in a stereo-plotter
  •  Adjacent but overlapping aerial photos are called stereo-pairs and are needed to determine parallax and stereo/3D viewing
  • AERIALTRIANGULATION
  •  Overlapping photography Endlap - ~60% Sidelap - ~20-30%
  •  RASTER AND VECTOR DATA THE DATA PREPARATION PLANMETRIC FEATURES DATA OUTPUT
  • Raster data are described by a cell grid, one value per cell Vector Raster Point Line Zone of cells Polygon
  •  Buildings Transportation Features Hydro Features Utilities Vegetation Breaklines DTM points Bridges
  • 13
  • Stereo Image Vector Data
  •  There is no common usage of the terms digital elevation model (DEM), digital terrain model (DTM) and digital surface model (DSM) in scientific literature The digital terrain model represents the bare ground surface The term Digital Elevation Model is often used as a generic term for DSMs and DTMs, only representing height information without any further definition about the surface
  •  Contour lines are lines drawn on a map connecting points of equal elevation Contour lines are useful because they allow us to show the shape of the land surface (topography) on a map This vertical spacing is referred to as the contour interval If the contour interval is 10 ft. Each the contour lines was a multiple of 10 ft.( i.e. 0, 10, 20, 30) In areas with high relief the contour interval is usually larger
  • DATA FOR THE 3D CITY MODELS The 3D city models contain data, which is related to the Spatial objects Those objects are generally topography, buildings, transportation, plant cover, infrastructure and other details related to the goal of application 3D city models are focused on buildings however it may contain roads, green cover, trees etc. according to the usage of model
  • 3D BUILDING MODEL The constructed 3D model
  • Photogrammetry …. Lecture 11 Dr. Steve Ramroop
  • ORTHO PHOTO GENERATION
  • ORTHO PHOTO GENERATION Ortophotos are photographs that have been corrected for distortions Distortions from the camera lens, and relief To use these orthophoto images as a map, it is of great importance to provide orthophoto images in high level of accuracy
  • ORTHOIMAGE
  • ORTHOIMAGElocation of bridges uncorrected and corrected forheight differences against the road below
  • conclusion3D Representation and Visualization of real world isonly possible with photogrammetry.The output ofphotogrammetry is typically a map Many of themaps we use today are created withphotogrammetry and photographs taken fromaircraft.
  • THANK YOU