# US 8,542,882 B2 · Method for determining flow conditions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,882 B2 - Document ID: US8542882B2 - Status: Granted - Kind: B2 - Application number: 13/202,397 - Filed: 2010-01-11 - Published: 2011-12-08 - Granted: 2013-09-24 - Earliest claimed: 2009-02-19 - Assignees: La Vision GmbH - Applicants: Berhnard Wieneke - Inventors: Berhnard Wieneke - Web page: https://patentgrep.com/patent/US8542882B2 ## CPC - G01P 5/001: {Full-field flow measurement, e.g. determining flow velocity and direction in a whole region at the same time, flow visualisation} - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract The invention relates to a method for determining flow conditions in a measured volume permeated by a fluid spiked with optically detectable particles. A plurality of two-dimensional images of the particle distribution is thereby created at each of a plurality of times, an estimated particle distribution is determined therefrom, and a three-dimensional displacement vector field is calculated. According to the invention, a transfer function for the image detectors used is first determined, by means of which the real distribution is mapped by the image detector. Starting from a roughly estimated initial distribution, and by means of the transfer function, virtual images of the estimated distribution are then calculated and compared to the associated real images. The estimated distribution is modified in an iterative method until sufficient matching of the virtual and real images has been achieved. ## Claims ### Claim 1 A method for determining flow conditions in a measuring volume (VR), which permeated by a fluid spiked with optically detectable particles, comprising the following steps: a) simultaneously recording at a first recording point in time (t0) of a first plurality of two-dimensional, real images (R10, R20) of a three-dimensional, real distribution of the particles by means of the same plurality of image detectors (12, 14) arranged spatially offset with respect to one another, b) repeating step a) at least at one second recording point in time (t1), c) determining for each recording point in time (t0, t1) a three-dimensional, estimated distribution (VI0, VI1) of the particles based on the real images and d) calculating a three-dimensional displacement vector field (VV) by comparing the estimated distributions (VI0, VI1), wherein e) determining for each image detector (12, 14) an optical transfer function (F1; F2) with which the real distribution (VR) is imaged by the image detector (12; 14) before carrying out step c), and wherein step c) starts with a roughly estimated starting distribution (VIstart) as an estimated distribution (VIj) and thereafter is carried out iteratively with the following sub-steps: c1) calculating two-dimensional, virtual images (I1j, I2j) of the estimated distribution on the basis of the transfer functions (F1, F2) determined in Step e, c2) comparatively determining differences between the virtual images (I1j; I2j) and the respectively assigned real images (R1j; R2j), c3) changing the estimated distribution (VIj) depending on the determined differences, and wherein the iteration is ended when a predetermined termination criterion has been reached. ### Claim 2 (depends on 1) The method according to claim 1, wherein the iteration is ended when the determined differences fall below predetermined tolerance values. ### Claim 3 (depends on 1) The method according to claim 1, wherein in Step c3 the estimated distribution (VIj) is changed regarding the number of particles and/or the position, the size and/or the intensity of at least one particle. ### Claim 4 (depends on 1) The method according to claim 1, wherein in step c2 in addition differences between virtual images (I1j; I2j) of different iteration steps are determined. ### Claim 5 (depends on 1) The method according to claim 1, wherein step b is carried out at more than one second recording point in time, and in step c3 each change of the estimated distribution is subjected to a plausibility check under the assumption that no non-marginal particle can disappear from the measuring volume. ### Claim 6 (depends on 1) The method according to claim 1, wherein in step e the optical transfer functions (F1, F2) are determined by recording real images of one or more known objects in the measuring volume and comparing the known object or objects with the recorded images. ### Claim 7 (depends on 6) The method according to claim 6, wherein a known object is a calibration plate or a calibration grid.