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    University of Nairobi: Photogrammetry Lab Report

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    1man1book
    This document is a photogrammetry lab report submitted by Njoroge Kagwi Maurice. It discusses the process of photogrammetry, which involves deriving ground measurements and object positions from photography without physical contact. The report outlines aerial photogrammetry, including planning flight lines, taking aerial photographs along predetermined paths, and interpreting the images to extract 3D spatial data using principles of triangulation and stereo parallax. The goal is to produce topographic maps and digital terrain models from aerial images.

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    University of Nairobi: Photogrammetry Lab Report

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    1man1book
    103 views4 pages
    This document is a photogrammetry lab report submitted by Njoroge Kagwi Maurice. It discusses the process of photogrammetry, which involves deriving ground measurements and object positions from photography without physical contact. The report outlines aerial photogrammetry, including planning flight lines, taking aerial photographs along predetermined paths, and interpreting the images to extract 3D spatial data using principles of triangulation and stereo parallax. The goal is to produce topographic maps and digital terrain models from aerial images.

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    survey

    Original Title

    Photogrammetry Labs Final

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    This document is a photogrammetry lab report submitted by Njoroge Kagwi Maurice. It discusses the process of photogrammetry, which involves deriving ground measurements and object positions from photography without physical contact. The report outlines aerial photogrammetry, including planning flight lines, taking aerial photographs along predetermined paths, and interpreting the images to extract 3D spatial data using principles of triangulation and stereo parallax. The goal is to produce topographic maps and digital terrain models from aerial images.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    103 views4 pages

    University of Nairobi: Photogrammetry Lab Report

    Uploaded by

    1man1book
    This document is a photogrammetry lab report submitted by Njoroge Kagwi Maurice. It discusses the process of photogrammetry, which involves deriving ground measurements and object positions from photography without physical contact. The report outlines aerial photogrammetry, including planning flight lines, taking aerial photographs along predetermined paths, and interpreting the images to extract 3D spatial data using principles of triangulation and stereo parallax. The goal is to produce topographic maps and digital terrain models from aerial images.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 4

    Photogrammetry Lab Report 2013

    UNIVERSITY OF NAIROBI

    COLLEGE OF ARCHITECTURE AND


    ENGINEERNG

    PHOTOGRAMMETRY LAB REPORT


    Engineering Surveying 2013
    NAME : NJOROGE KAGWI MAURICE
    Reg. No : F16/1334/2010

    F16/ 1334/ 2010 NJOROGE KAGWI MAURICE


    INTRODUCTION:
    WHAT IS PHOTOGRAMMETRY?
    This is the process by which ground measurements are derived and
    determined through photography.
    In this case, the object measurements and relative positions are determined
    without touch.
    Photogrammetry can be divided into
    Range photogrammetry (aerial photogrammetry) and
    Close range photogrammetry (mostly terrestrial photogrammetry).
    In close range photogrammetry, cameras are close to the object either hand
    held or mounted on a tripod.
    Aerial photogrammetry is however done from great vertical heights and covers
    great areas, normally from planes or satellites.
    Such photographs are termed vertical photographs.
    Aerial photogrammetry is mainly used to produce large scale topographical
    maps and digital terrain models (DTM) representing the terrain relief. It makes
    it possible to prepare contoured plans from the aerial photographs.

    AERIAL PHOTOGRAMMETRY
    1 .PLANNING
    The area to be surveyed using aerial photography is planned and the flight
    lines determined.
    The whole area must be covered by the photographs and therefore there must
    be overlap. This is called stereo overlap.
    Forward overlap allowed is 65%+/-5% while side lap allowed is in the range of
    25%+/-5%.

    2. DETERMINATION OF FLIGHT LINES


    The area of interest is divided into runs which form the flight lines.

    F16/ 1334/ 2010 NJOROGE KAGWI MAURICE

    The runs are parallel to each other spanning the whole area of study and
    ensuring overlaps for the photographs are achieved.

    3. PROCESS
    With the aerial camera in the body of the aircraft, photographs are taken along
    the prearranged flight paths, with the optical axis of the camera pointing
    vertically down.
    4. INTERPRETATION
    A single photograph contains a lot of detailed information about the area
    under survey. However, a photograph cannot be a map of the ground or a plan
    of a building. At best, a photograph shows the view through the camera with
    distortions due to the optics of the camera, the atmosphere and the position
    and orientation of the camera.
    In principal, it is 3D coordinates that define the locations of object points on
    the ground surface and their relative positions to each other. However, the
    image (photography) coordinates obtained define the locations of the object in
    plane.
    Through photogrammetry, the above process is reversed. It converts, or maps,
    the flat 2-dimensional images back into the real 3-dimensional world.
    This is derived from the existing ground control points for geo-reference.
    Photogrammetry therefore enables the user to derive metric information
    about the terrain, or any three-dimensional object by making measurements
    on photographs of that object element image from pairs of photographs. As a
    minimum, two different photographs are needed to reconstruct the 3dimensional object. The more photographs taken and used, the extra the
    information and the process is improved. The 3-dimensional coordinates
    produced from the measurements of multiple photographs are the end result
    of photogrammetry.

    F16/ 1334/ 2010 NJOROGE KAGWI MAURICE

    Photogrammetry uses the basic principle of Triangulation, whereby


    intersecting lines in space are used to compute the location of a point in all
    three dimensions. However, in order to triangulate a set of points one must
    also know the camera position and aiming angles (together called the
    orientation) for all the pictures in the set. A process called resection does this.
    Some camera calibration has to be done in order to define its errors and
    remove them from the process.
    The image scale will dictate the magnitude of the linear and radial
    displacements in the image. The change in the position of an object from one
    photograph to the next is known as stereoscopic parallax. The amount of
    parallax depends on the objects height. Higher points have greater parallax.
    Given any two overlapping images, a stereo pair, it is possible to view both
    images simultaneously to replicate a stereo binocular view.
    5. INSTRUMENTATION
    Photographs are taken using digitalized cameras or even the analogue type
    where images are stored in films.
    Using the stereoscopic pairs of photographs processed; study of the area
    terrain and configuration can be done using Stereoscopic binoculars which use
    lenses to integrate the 3d perspective of the photographs.
    The photographs can also be used to plot the topographical maps of large scale
    of the areas under study using the various instruments available such as the
    modern computer work stations or the old stereo plotting machines.
    GENERALIZED PROCESS

    F16/ 1334/ 2010 NJOROGE KAGWI MAURICE

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