JPS60218072A - Speed measuring device - Google Patents

Abstract

PURPOSE:To measure the speed of a moving body on real-time basis by calculating the time difference and distance between two points of time where time variation in the length of an overlap of an optionally set closed curve and the track of a body image is maximum. CONSTITUTION:An image of the moving body is caught by a television camera 4 and the closed curve 2 is set on a screen by a closed curve setter 5 to extract a video signal on the curve 2. A binary coding circuit 7 codes the signal into a binary signal of ''1'' and ''0'' according to whether the body is present or absence and divides the resulting signal to systems S1-S3. The system S1 is inputted to a superposing device 10, which ORs picture elements of the input signal with those of a picture element array superposed at last time to generates an OR output. The output shows the overlap of the track of the object image 3 and the curve 2. The output of the supersposing device 10 is inputted to an adder 11 to sum up numbers of all picture elements, and thus the number of picture elements where the curve 2 overlaps the track of the object image 3; and a decision device 12 detects an abrupt increase in the number of picture elements and sends it output to a speed operator 5. The operator 15 stores the time and numbers of picture elements on the curve 2 which overlap the object image 3 newly and operates the speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device for measuring the moving speed of an object from a moving image, and particularly to a speed measuring device suitable for measuring the moving speed in real time.

[Background of the invention]

Two different methods of determining the moving speed of an object from a moving image
A method is known in which the moving speed of an object is calculated from the moving distance of the object by comparing images at different times. 'Journal of Visual Flow Chemistry VoJ, 3
．． NO, 10r1983), PI93~P 1g8''
In this method, multiple tracer particles are mixed into the fluid and two different
There is a known example in which a photograph of a tracer particle at a given time is input into a computer to calculate the moving speed of the tracer particle.

However, in this example, to determine the position of the tracer particle, the contour of the tracer particle is determined by the Freeman method, and the position of the tracer particle is determined while determining whether it is a tracer particle or not. , the number of judgments increases, making real-time processing difficult.

[Purpose of the invention]

An object of the present invention is to provide a speed measuring device that can measure the moving speed of an object in real time from a moving image without parallelizing or increasing the speed of hardware.

[Summary of the invention]

If two-dimensional image information is input and processed to determine the moving speed of an object from a moving image, both storage capacity and processing time will increase. In the present invention, by setting an arbitrary closed curve on an image and processing only the image on the closed curve, the amount of information to be processed can be greatly reduced compared to processing a two-dimensional image, and the speed can be increased. This was born out of consideration that it is possible to

FIG. 1 shows the relationship between a closed curve 2 set in one image 1 and an object image 3 on the image. In terms of signal processing, the image 1 can be composed of, for example, a signal train of a television camera, or can also be composed of a video signal such as an ultrasound image.

The present invention relates to a speed measuring device that extracts a video signal on a closed curve 2 from an image 1 and measures the moving speed of an object. The video signal from the closed curve 2 is composed of N pixels shown in FIG. When each pixel is assigned a number from 1 to N, the first pixel represents the position (xi, yi l ) of image 1. This numbering does not need to be performed from the starting point, but is random. Next, project the object and set the value of the pixel on the closed curve 2 that overlaps with the object image 3 to 1, and the value of the pixel that does not overlap to 0.The number of pixels whose pixel value is 1 is calculated as follows. Now, suppose that the object image 3 is moving from right to left in FIG. 1, the closed curve 2 is set smaller than the object image 3, and the object image passes through the center of the closed curve.

FIG. 3A shows the temporal change in the number L1 of pixels overlapping the object image 3. When object image 3 starts to overlap closed curve 2 at time [1, object image 3 and closed curve 2 are in contact with each other, so object image 3
The number L1 of pixels on the closed curve 2 that overlaps rapidly increases, and even when the object image 3 and the closed curve 2 all overlap at time t2, the object image 3 and the closed curve 2 are in contact with each other, so L+ increases rapidly. time【..

1, by detecting the number of the pixel that newly overlaps with the object, the time [. , [1] The position of the object image 3 on the image 1 is known, and the moving speed of the object can be determined.

Incidentally, there may be cases where the closed curve 2 is larger than the object image 3, or where the object image 3 passes through an end of the closed curve 2.

It is good to be able to measure in the same way in these cases as well. Therefore, the following four cases will be considered. Like the stone shown in Figure 3, C) Object image 3 is larger than closed curve 2 and passes through the entire closed curve.

(b) The object image 3 is larger than the closed curve 2 and passes through a part of the closed curve.

0 Object image 3 is smaller than closed curve 2 and passes through two parts of the closed curve.

(1'j The object gR3 is smaller than the closed curve 2 and passes through a part of the closed curve.

The time variation of the length L included by the object image 3 in the closed curve 2 is as shown in Fig. 4 A in case of case Fig. 4 B (in case of 0 Fig. 4 C in case of O), respectively. For the case, turtle.,1 time and,
At that time, hidden pixels can be detected and the speed can be increased. As mentioned above, since there are four changes in L+, tO+t+
It is also necessary to prepare four copies of the detection method.

By examining the temporal changes of all pixels on the closed curve 2, it is possible to determine which of the four cases corresponds to the case, but if there are many pixels on the closed curve 2, the number of determinations will increase. Also,
t in the same way. , [If you choose I, there is no need to make complicated judgments. This can be achieved in the following way.

The pixel string captured at the fifth time on the closed curve 2 that has a value of 1.0 depending on the presence or absence of an object is defined as AJ, and for each pixel, take the logical sum of AJ at all times. day.

8=A, ■A,, (+)... ■Al (■; logical sum) This K results in a pixel row representing the overlap of the locus of the object image 3 and the closed curve 2. In the case of (4), the time change of the pixels where the locus of the object image 3 and the closed curve 2 overlap, that is, the number of pixels whose value is 1 in the pixel row 8, is as follows. In case of Fig. 5B (0 case Fig. 5C case ■ Fig. 6D) In all four cases, the time to measure the position of object image 3 is
The first time is time t when L2 increases rapidly, and the second time is time 1 when L2 increases rapidly. You can choose to.

[Embodiments of the invention]

Hereinafter, the procedure of an embodiment of the present invention will be explained using FIG. 6.

(2): Set a closed curve 2 on the image 1, and confirm that the object image 3 does not lie inside the set closed curve 2.

The shape of the closed curve 2 to be set is preferably a circle so that the object image 3 exhibits a similar response no matter which direction it moves.

■: Number the pixels on the closed curve 2 as shown in Figure 2,
Detect the position of each pixel.

(a); Pixel row 1 is defined as the overlap of closed curve 2 and object image 3. Pixel row 2 is defined as an overlap between closed curve 2 and the locus of object image 3. In order to detect the time when the number of pixels L2 at the overlap between the loci of the closed curve 2 and the object image 3 increases rapidly (time Is in FIG. 5), a threshold value is set to α for detecting a change in L2.

(2): The object image 3 is periodically photographed, and the value of the pixel that overlaps with the object image 3 is set to 1, and the value of the pixel that does not overlap is set to 0.

(2) For pixels with the same number, take the logical sum of pixel column 1 and pixel column 2 and set pixel column 2. That is, the pixel row 2 shows the overlap of the trajectory of the object image 3 and the closed curve i$12.

■; Pixel row 2L7? Calculate the number of pixels whose value is 1.

■; Engineering 4. Increased DL from the previous time! DL! = L
x, Lta (Ltm; value of previous time).

■Detect whether or not iLt has increased rapidly. If the increase is greater than the increase at the previous time by more than the threshold value α, it is assumed that there has been a sudden increase, and the process proceeds to [Stocks]. If not, ■.

0; Current time 1. Incorporate.

0: Detect pixels whose value changes from 0 to 1 in pixel row 1. This detection method has two methods: one detects the difference from the previous time and the number Ni of the pixel with a value of 1, and the other detects the pixel number Ni of the pixel whose value is 1. Detects the number Nj of .

Q, 2e hour,' 1. 't'? ! : 2 When the horn pixels N* and Nx are detected, proceed to Il). If not, proceed to ■.

0; Pixel number N, , N! corresponding to fiHx+,
y+) and (x,,y,) to calculate the velocity 1u, V).

FIG. 7 shows the configuration of an embodiment of the present invention. A moving object is captured by a television camera 4. A closed curve setter 5 sets a closed curve 2 on the screen of a television camera 4 and extracts a video signal on the closed curve 2.

The binarization circuit 7 determines whether there is an object or not. O to 2
It has a high value and is divided into the Sl+ 82+ Ss lineage.

The system of S is input to the superimposition device 10, and the logical sum of the pixel string taken and superimposed at the previous time and the logical sum for each pixel are outputted. This result shows that the trajectory of the object 113 and the closed curve 2 overlap. The output of the superimposition device 10 is input to the adder 11, which calculates the sum of all pixel numbers, and calculates the number of pixels 1. .

Calculate. The determiner 12 detects a sudden increase in L, and outputs it to the speed calculator 15. The speed calculator 15 receives the signal from the determiner 12, stores the pixel number Ni on the closed curve 2 that newly overlaps the object image 3 at time 1°, and calculates the speed.

As described above, according to this embodiment, only pixels on a closed curve are extracted from a two-dimensional image, and operations between pixels are only simple logical OR, addition, and subtraction. It is possible to measure the moving speed of a large object.

〔Effect of the invention〕

As described above, according to the present invention, the speed of a moving object can be determined in real time from a moving image without increasing the speed of hardware.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an image, Figure 2 is a schematic diagram of pixels on a closed curve, Figure 3 is a schematic diagram of a closed curve and an object image, and Figure 4 is a diagram of changes over time in the number of pixels on a closed curve that overlaps with the object image. , Figure 5 is a time change diagram of the number of pixels on a closed curve that overlaps with the trajectory of the object image, Figure 6
The figure is a diagram showing an example of an implementation procedure of the present invention, and FIG. 7 is a diagram showing an embodiment of the present invention. l... Image, 2... Closed curve, 3... Object image, 4...
... TV camera, 5... Closed curve setting device, 6... Timing controller, 7... Binarization circuit, 8...
Delay circuit, 9... Image memory, 10... Superimposition device, 1
1...Adder, 12...Determiner, 13...Subtractor, 14...Position detector, ----0 ・--m=1 64) (θ) (C) (ρ ) (A) (β) 7+ Ia #M #閤(A) (βjislide 7m

Claims (1)

[Claims] 1. An arbitrary closed curve is set on the image, and the time difference between two times when the time change in the length of overlap between the closed curve and the trajectory of the object image is maximum, and the coordinates of the corresponding curve are determined. A speed measuring device characterized in that the position and moving speed of an object are determined from the distance from the object. 2. In claim 1, a closed curve setter is provided for extracting a video signal on a closed curve from the video signal, and an addition model is provided for adding the video signals on the closed curve, and the result of the addition is determined; A speed measuring device characterized by detecting the position of an object image at two times and measuring the moving speed of the object.