Close Range Photogrammetry

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Close Range Photogrammetry

• Chris Hart
• CEE498 Experimental Methods

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Outline

• What is photogrammetry?
• Types of photogrammetry
• How it works!
• Necessary equipment
• PhotoModeler (Photogrammetry software)
• Civil engineering applications
• Accuracy of close range photogrammetry
• Conclusions and Challenges

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What is photogrammetry?

• Photogrammetry A remote sensing technology
  whereby geometric properties about objects are
  determined from photographic images
• The fundamental principle behind photogrammetry
  is triangulation
• Two Parts
• Photography Photographic principles are
  required to gather images
• Metrology - Techniques used to produce
  3-dimensional coordinates from two-dimensional
  photographs.

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Types of Photogrammetry

• Aerial Photogrammetry

• Close Range Photogrammetry

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Equipment

• Digital Camera
• High resolution camera (preferred gt 7 MP)
• Lens/Camera have been calibrated
• Targets
• Retro-reflective targets
• Coded targets preferred
• Circular targets
• Hard-body tooling targets
• Software
• PhotoModeler
• There are many other software packages which may
  include specific applications

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Civil Engineering Applications

• 3D coordinate information about a test setup
• NEES Wall Project
• 3D surface rendering for FEM modeling (NURBS
  surfaces and curves)
• Precise measuring of 3D points in space for
  measuring relative strains/displacements (Still
  being developed, but promising)

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PhotoModeler

• Has ability for sub-pixel marking
• High contrast circular targets can be more
  accurately targeted
• Programmability Use a DDE (Dynamic Data
  Exchange) interface to control certain functions
  in PhotoModeler and to have data fed in through
  other Windows applications such as MatLab!
• PhotoModeler Video (PMV)

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Photogrammetry Accuracy
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Conclusions and Challenges

• Powerful tool for gathering full field 3D
  coordinate (non-contact) information about an
  object or test structure
• Cheap compared to advanced real-time full field
  measurement systems such as Krypton
• Requires a lot of user knowledge and experience
• Post processing is not fully automated and time
  consuming

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Links and Questions

• American Society of Photogrammetry and Remote
  Sensing
• http//www.asprs.org
• International Society of Photogrammetry and
  Remote Sensing
• http//www.isprs.org/
• PhotoModeler
• http//www.photomodeler.com