Application of resection for PSP image alignment

Venkatakrishnan, L (2003) Application of resection for PSP image alignment. Project Report. National Aerospace Laboratories, Bangalore.

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Abstract

The Pressure Sensitive Paint (PSP) technique yields surface pressure distributions by ratioing two images of a PSP-coated wind tunnel model taken at wind-off and wind-on conditions. Image alignment prior to ratioing is crucial to the accuracy of PSP systems. Most earlier approaches for alignment employed an image warping approach prior to ratioing and thereafter the two-dimensional image data was mapped on to three-dimensional model space. This approach may result in larger errors when the bodies are significantly three-dimensional and involving large spatial gradients of pressure. Analytical photogrammetric methods can be used to map quantitative image data to three-dimensional object space. While photogrammetric techniques to map each image to the grid prior to ratioing have been both suggested and adapted recently to PSP applications, no comparisons have been presented against pressure port data. This report outlines the various transforms used for image warping and their error on a set of PSP data. The photogrammetric approach is then applied by using a comprehensive camera model, which takes into account the various error sources to map all images onto a body surface grid prior to ratioing. Comparisons are made with pressure port data showing excellent agreement and the higher resolution of the approach making it suitable for significantly three-dimensional bodies and regions of high gradients.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: Pressure Sensitive Paint, Image alignment, Resection, Photogrammetric methods
Subjects: AERONAUTICS > Aerodynamics
Depositing User: Smt Bhagya Rekha KA
Date Deposited: 24 Aug 2011 08:12
Last Modified: 24 Aug 2011 08:12
URI: http://nal-ir.nal.res.in/id/eprint/9926

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