Method for measuring a particle precipitation rate, and device thereof

Patent metadata

Field	Value
Publication number	US-2017363776-A1
Application number	US-201615543147-A
Country	US
Kind code	A1
Filing date	Jan 11, 2016
Priority date	Jan 13, 2015
Publication date	Dec 21, 2017
Grant date	—

Abstract

A method for measuring a particles' precipitation rate includes the steps of acquiring at least one first image during a precipitation event through an image acquisition device having a sensor and lens; detecting the particles of the precipitation in the at least one first image by subtracting a background of the first image and setting a brightness threshold for detecting the particles, the particles being visible as a plurality of streaks in the image, wherein a first portion of the plurality of streaks comprises blurred streaks, and a second portion of the plurality of streaks comprises focused streaks; determining an apparent diameter and an apparent length for the plurality of streaks; estimating an actual diameter and an actual length for the plurality of streaks by resolving an equations' system having three equations and three unknowns, namely the actual diameter, the actual length and a depth position of the plurality of streaks, the depth position being the position of each particle from the lens, in which a first equation has the actual diameter as unknown in function of the depth position, a second equation has the actual length as unknown in function of the depth position and a third equation equals the theoretical terminal velocity of the particles with an estimated velocity of the particles in function of the depth position; estimating the velocity of the particles based on the ratio between a net streak length and an exposure time used to take at least one first image; estimating the particles' precipitation rate based on the actual diameter and the velocity (v).

First claim

1 . A method for measuring a particles' precipitation rate, said method comprising the steps of:
acquiring at least one first image during a precipitation event through an image acquisition device having a sensor and lens; detecting said particles of said precipitation in said at least one first image by subtracting a background of said first image and setting a brightness threshold for detecting said particles, said particles being visible as a plurality of streaks in said image, wherein a first portion of said plurality of streaks comprises blurred streaks, and a second portion of said plurality of streaks comprises focused streaks; determining an apparent diameter and an apparent length for said plurality of streaks; estimating an actual diameter and an actual length for said plurality of streaks by resolving an equations' system having three equations and three unknowns, namely said actual diameter said actual length and a depth position of said plurality of streaks, said depth position being the position of each particle from said lens, in which a first equation has said actual diameter as unknown in function of said depth position, a second equation has said actual length as unknown in function of said depth position and a third equation equals the theoretical terminal velocity of said particles with an estimated velocity of said particles in function of said depth position; estimating said velocity of said particles based on the ratio between a net streak length and an exposure time used to take said at least one first image; estimating said particles' precipitation rate based on said actual diameter and said velocity

2 . The method according to claim 1 , wherein it is provided for acquiring a second image through said image acquisition device and for subtracting said second image to said first image for deleting a background of said first image.

3 . The method according to claim 1 , wherein said method provides for determining said depth position of a particle in a sampled volume.

4 . The method according to claim 1 , wherein said velocity of said particles is estimated based on said depth position of the particles.

5 . The method according to claim 1 , wherein said particles' precipitation rate is obtained by averaging precipitation rates of a set of acquired images.

6 . The method according to claim 1 , wherein said particles are in liquid or solid state and comprise one or more of the elements of the group consisting of: hydrometeors, settling particles, chemical particles.

7 . A computer product which can be loaded into a memory of said image acquisition device comprising portions of software code adapted to implement the method of claim 1 .

Assignees

• Torino Politecnico

Inventors

• Allamano Paola
• Croci Alberto
• Laio Francesco

Classifications

• G01W1/14 Primary

  Rainfall or precipitation gauges (measuring volume in general G01F) · CPC title

• G06T2207/30192

  Weather; Meteorology · CPC title

• G06T7/20

  Analysis of motion (motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51) · CPC title

• G06T7/62

  of area, perimeter, diameter or volume · CPC title