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Fluid motion vector estimation method based on space-time image

A fluid motion and image technology, used in fluid velocity measurement, image enhancement, image analysis, etc., can solve problems such as reducing the accuracy and reliability of motion vector estimation, and poor adaptability of local flow fields.

Active Publication Date: 2014-08-20
HOHAI UNIV
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Problems solved by technology

Using a fixed size observation window will reduce the accuracy and reliability of motion vector estimation due to poor adaptability to the local flow field

Method used

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Embodiment Construction

[0034] The technical scheme of the present invention is described in detail below in conjunction with accompanying drawing:

[0035] The workflow of the motion vector estimation method of the present invention is as follows: figure 1 shown. There are four main steps:

[0036] (1) Image sequence acquisition

[0037] Firstly, the duration T of a single time-averaged flow field measurement and the time interval Δt of each frame of image acquisition are set. T should be large enough to eliminate the random measurement error caused by the flow velocity pulsation effect, and should be small enough to meet the time resolution of the measurement; Δt should be selected according to the shooting field of view, image resolution and flow to be measured, and should be large enough to ensure the accuracy of the results The discretization accuracy should be small enough to ensure the continuity of the distribution of water flow tracers in the image sequence. Then calculate the length M=T...

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Abstract

The invention discloses a fluid motion vector estimation method based on a space-time image and belongs to the technical field of flow field measurement. The method firstly adopts a single camera to acquire a fluid image sequence at fixed time intervals; then an aberration correction linear conversion method is adopted to carry out optical distortion correction on images and a group of speed measurement lines are arranged in a flow measurement direction, wherein each speed measurement line uses a pixel as an x-coordinate and a time as a y-coordinate to synthesize a time-space image; then frequency-spectrum analysis is carried out on the time-space images which undergo edge detection and a discrete approximation method is adopted to solve a frequency-spectrum main direction and obtain a texture main direction vertical to the frequency-spectrum main direction; and according to a mapping relation of an object-space coordinate and an image-space coordinate, physical sizes of the speed measurement lines are solved and the value of a one-dimension flow speed vector is calculated through combination of the texture main direction and the time intervals so as to realize time-averaged flow field calibrating. The fluid motion vector estimation method based on the space-time image can be used for time-averaged flow field measurement of natural tracing water flows such as river surfaces and the like and is especially suitable for online monitoring of flow rates of rivers in a flood period.

Description

technical field [0001] The invention relates to a method for estimating a fluid motion vector, in particular to a method for estimating a fluid motion vector based on spatio-temporal images, and belongs to the technical field of flow field measurement. Background technique [0002] There are a large number of fluid microclusters with no fixed mass and relative motion in the fluid, which makes the motion of the fluid more complex than that of rigid bodies and solids. In the past two decades, the development of optics, electronics and computer technology has promoted the realization and application of particle image velocimetry (PIV), a non-contact instantaneous full-field flow velocity measurement technology. It obtains the size, direction, characteristics and distribution of local fluid motion displacement and velocity through the analysis and calculation of particle image sequences, which greatly improves the measurement capabilities of various complex flows in the laborato...

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Application Information

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IPC IPC(8): G06T5/00G06T7/00G01P5/18
Inventor 张振徐枫韩磊董伟王慧斌
Owner HOHAI UNIV
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