Method and system for determining the velocity of a moving fluid surface
First Claim
1. A method for determining velocity of a moving fluid surface, comprising the following steps S1 to S5:
- S1) receiving by a processor a sequence of digital images of the moving fluid surface taken by at least one digital camera;
S2) comparing, with the processor, a first digital image from the sequence of digital images taken at time t1 with a second digital image from the sequence of digital images taken at time t2 by building the absolute difference between the first digital image and the second digital image in order to distinguish fluid moving patterns of the fluid surface from non-moving fluid and non-moving non-fluid parts and to obtain a first processed image comprising the fluid moving patterns, wherein t2 is later than t1;
S3) comparing, with the processor, a third digital image from the sequence of digital images taken at time t3 with a fourth digital image from the sequence of digital images taken at time t4 by building the absolute difference between the third digital image and the fourth digital image in order to distinguish said fluid moving patterns of the fluid surface from non-moving fluid and non-moving non-fluid parts and to obtain a second processed image comprising said fluid moving patterns, wherein t3 and t4 are later than t1 and wherein t4 is later than t3;
S4) comparing, with the processor, the first and second processed images in order to determine the spatial displacements of said fluid moving patterns; and
S5) determining, with the processor, from the spatial displacements, the velocity,wherein in step S4 spatial displacements are determined by evaluating a cross-correlation between subwindows of the first and second processed images.
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Abstract
A method for determining the velocity of a moving fluid surface, which comprises the following steps S1 to S5: S1) taking a sequence of images of the moving fluid surface by at least one camera; S2) comparing a first image from the sequence with a second image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a first processed image (im_1f) comprising the moving patterns; S3) comparing a third image from the sequence with a fourth image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a second processed image (im_2f) comprising the moving patterns; S4) comparing the first and second processed images in order to determine the spatial displacements of the moving patterns; and S5) determining from the spatial displacements the velocity.
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Citations
17 Claims
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1. A method for determining velocity of a moving fluid surface, comprising the following steps S1 to S5:
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S1) receiving by a processor a sequence of digital images of the moving fluid surface taken by at least one digital camera; S2) comparing, with the processor, a first digital image from the sequence of digital images taken at time t1 with a second digital image from the sequence of digital images taken at time t2 by building the absolute difference between the first digital image and the second digital image in order to distinguish fluid moving patterns of the fluid surface from non-moving fluid and non-moving non-fluid parts and to obtain a first processed image comprising the fluid moving patterns, wherein t2 is later than t1; S3) comparing, with the processor, a third digital image from the sequence of digital images taken at time t3 with a fourth digital image from the sequence of digital images taken at time t4 by building the absolute difference between the third digital image and the fourth digital image in order to distinguish said fluid moving patterns of the fluid surface from non-moving fluid and non-moving non-fluid parts and to obtain a second processed image comprising said fluid moving patterns, wherein t3 and t4 are later than t1 and wherein t4 is later than t3; S4) comparing, with the processor, the first and second processed images in order to determine the spatial displacements of said fluid moving patterns; and S5) determining, with the processor, from the spatial displacements, the velocity, wherein in step S4 spatial displacements are determined by evaluating a cross-correlation between subwindows of the first and second processed images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification