3D Fourier transform-based thoracico-abdominal surface measurement method

Abstract

A 3D Fourier transform-based thoracico-abdominal surface measurement method belongs to the technical field of structured light 3D measurement. The method comprises the following steps: projecting three stripe images of different frequencies onto a thoracico-abdominal surface doing breathing exercise, using a camera to collect the stripe images, and carrying out 3D Fourier transform on the three stripe images separately; after 3D Gaussian filtering of the transform results, carrying out Fourier inverse transform, and extracting a package phase; unwrapping the phase to get an absolute phase; and finally, converting the absolute phase into height information based on the trigonometry principle. According to the invention, a stripe pattern sequence of a thoracico-abdominal surface changing with time is taken as a whole, spatial images and a time sequence are combined, and a 2D-FFA method is expanded into a 3D-FFA method by adding a time dimension, so that the interference signal frequency component in the time dimension is removed, and the accuracy of package phase extraction is improved; and further, by using a three-frequency phase unwrapping method, the reliability of package phase unwrapping is improved, and the anti-interference ability of 3D surface measurement is improved.

Description

technical field [0001] The three-dimensional Fourier transform chest and abdomen surface measurement method belongs to the technical field of structured light three-dimensional measurement. Background technique [0002] The three-dimensional motion measurement of the human chest and abdomen surface has important application prospects in the field of medical analysis, such as inferring tumor motion through the chest and abdomen surface respiratory motion, providing a basis for precise radiotherapy, etc. At present, the optical measurement method is recognized as the most practical and potential solution. Among them, Fourier transform profilometry only needs a deformed fringe pattern to obtain the height information of the surface of the measured object, which is most suitable for dynamic measurement of simple flat surfaces such as the surface of the human chest and abdomen. However, due to the existence of spectrum leakage and aliasing, as well as interference signals from t...

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Problems solved by technology

However, due to the existence of spectrum leakage and aliasing, as well as interference signals from the environment, the measured object, and the measurement system, errors occur in the phase extraction and unfolding of the package, which in turn causes errors in 3D measurement. This is what Fourier transform profilometry needs to solve. main problem

[0003] The one-dimensional Fourier fringe analysis (1D-FFA) method separates the frequency components of the useful signal along the one-dimensional direction by selecting an appropriate frequency domain filter, but cannot filter out the frequency components of other dimensions that are aliased in the frequency components of the useful signal. interference signal

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