CN103197090B - Video speed measuring method based on feature point change - Google Patents

Abstract

The invention relates to a video speed measuring method based on feature point change. The video speed measuring method based on the feature point change is characterized by comprising the steps that a video probe is used for shooting continuous photos of a certain road at fixed time intervals or continuously shooting videos of the certain road, when a moving object enters a scene shot by the video probe, features of the moving object are extracted, and the speed of the moving object is calculated through displacement amount change of steps. According to the video speed measuring method based on the feature point change, an existing video probe is used for collecting continuous photos or video streaming, length calculation is conducted to pixel changing amount of feature points in the continuous photos or the video streaming, the speed of a measured object can be obtained by the fact that time difference is further divided, the addition of additional equipment is needless, a system is simple, and cost is low.

Description

The video frequency speed-measuring method of distinguished point based change

Technical field

The present invention relates to a kind of video frequency speed-measuring method, particularly relate to the video frequency speed-measuring method of a kind of distinguished point based change, belong to vehicle speed measuring method technical field.

Background technology

At present, vehicle speed measuring technology mainly contains ground sensing coil speed measuring (or infrared test the speed) and radar velocity measurement (or laser velocimeter) etc.Ground sensing coil speed measuring technology utilizes electromagnetic induction principle, when having vehicle through ground induction coil region, coil flux amount changes, export trigger pip, prompting has car to pass through, therefore can two ground induction coil regions being set on highway pavement certain distance, by monitoring out the mistiming of vehicle through these two regions, can car speed being calculated.Because ground induction coil needs road pavement cutting, road pavement certain destruction can be had.The infrared principle that tests the speed and ground induction coil similar, only with the turnover of infrared detection vehicle.

Radar velocity measurement then utilizes Doppler effect, is calculated the speed of transported object by radar return relative to the frequency displacement of transmitted wave.Radar velocity measurement system for take measurement of an angle require higher, velocity-measuring system need just to object of which movement to, measured deviation angle should be less than 10 degree.

Above-mentioned two kinds of method of testings all need additionally to increase corresponding equipment to realize the measurement of speed, add the complexity of equipment to a certain extent, improve system cost.

Summary of the invention

The object of this invention is to provide a kind of method that existing video probe can be utilized to measure the speed of a motor vehicle.

In order to achieve the above object, technical scheme of the present invention there is provided the video frequency speed-measuring method of a kind of distinguished point based change, and it is characterized in that, step is:

Step 1, by video probe, with Fixed Time Interval, continuous picture or lasting capture video are taken to certain road, when there being mobile object to enter in the scene of video probe shooting, the feature of mobile object is identified, extract current shooting to picture or current video frame on this feature record the coordinate (x of its corresponding pixel N on photo current or frame of video ₁, y ₁), and record current time t ₁;

Step 2, after a Preset Time, extract current shooting to picture or current video frame on same characteristic features record the coordinate (x of its corresponding pixel M on photo current or frame of video ₂, y ₂), and record current time t ₂;

Step 3, the size making picture or frame of video are m × n, and pixel is of a size of a × b, calculate the speed V of mobile object, wherein, T=t ₂-t ₁, A is the coordinate points corresponding to video probe subpoint on the ground on picture or frame of video, then have:

$\mathrm{AN}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}+\mathrm{arctg}[(\frac{n}{2}-x_1)\×a]/{\mathrm{DE}}^{\′}\};$

$\mathrm{AM}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}-\mathrm{arctg}[(\frac{n}{2}-x_2)\×a]/{\mathrm{DE}}^{\′}\},$ Wherein, AD is the vertical height that video probe is installed, and B publishes picture the lower boundary of picture and the intersection point of perpendicular captured by video probe, the lens focus that DE ' is video probe.

Preferably, the feature of described mobile object is car plate or car beacon light.

The present invention adopts in the continuous picture of existing video probe collection or video flowing, carries out length computation to unique point pixel variations amount wherein, can obtain object being measured speed divided by the mistiming, and without the need to increasing extra equipment, system is simple, and cost is low.

Accompanying drawing explanation

Fig. 1 is algorithm principle figure of the present invention;

Fig. 2 is the partial enlarged drawing of Fig. 1.

Embodiment

For making the present invention become apparent, hereby with preferred embodiment, and accompanying drawing is coordinated to be described in detail below.

The invention provides the video frequency speed-measuring method of a kind of distinguished point based change, the steps include:

Step 1, by as the camera of video probe or video camera, with Fixed Time Interval, continuous picture or lasting capture video are taken to certain road, when there being mobile object to enter in the scene of video probe shooting, the feature being easier to identify of mobile object is identified.When mobile object is automobile, feature can be chosen to be car plate or car beacon light or vehicle in the projection of the road in picture or video that is taken.Extract current shooting to picture or current video frame on this feature, the method extracting feature adopts existing image characteristic extracting method just can realize, provide after feature extraction extract characteristic quantity to angular coordinate, thus record the coordinate (x of its corresponding pixel N on photo current or frame of video ₁, y ₁), and record current time t ₁, wherein true origin can be chosen at the upper left corner of picture or frame of video, the upper right corner, the lower left corner or the lower right corner.

Step 2, after a Preset Time, extract current shooting to picture or current video frame on same characteristic features record the coordinate (x of its corresponding pixel M on photo current or frame of video ₂, y ₂), and record current time t ₂.

Step 3, the size making picture or frame of video are m × n, and pixel is of a size of a × b, calculate the speed V of mobile object, wherein, T=t ₂-t ₁, A is the coordinate points corresponding to video probe subpoint on the ground on picture or frame of video, then have:

$\mathrm{AN}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}+\mathrm{arctg}[(\frac{n}{2}-x_1)\×a]/{\mathrm{DE}}^{\′}\}---\left(1\right);$

$\mathrm{AM}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}-\mathrm{arctg}[(\frac{n}{2}-x_2)\×a]/{\mathrm{DE}}^{\′}\}---\left(2\right),$ In formula (1) and formula (2), AD is the vertical height that video probe is installed, and B publishes picture the lower boundary of picture and the intersection point of perpendicular captured by video probe, the lens focus that DE ' is video probe.

Composition graphs 1 and Fig. 2, D is the installation site of video probe, E point is the medium line of picture or frame of video and the intersection point of perpendicular, and B ', M ', E ', N ', C ' are respectively B, M, E, N, C projection in CCD, then the derivation of formula (1) is:

AN＝AD×tg∠AND＝AD×tg(∠ADB+∠BDE+∠EDN) (3)；

$\∠\mathrm{ADB}=\mathrm{atctg}\frac{\mathrm{AB}}{\mathrm{AD}}---\left(4\right);$

$\∠\mathrm{BDE}=\∠B^{\′}{\mathrm{DE}}^{\′}=\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}---\left(5\right);$

$\∠\mathrm{EDN}=\∠E^{\′}{\mathrm{DN}}^{\′}=\mathrm{arctg}(\frac{n}{2}\×a)/{\mathrm{DE}}^{\′}---\left(6\right);$

Then can obtain formula (1) in conjunction with formula (3) to (6), in like manner can obtain formula (2).

Claims (2)

1. a video frequency speed-measuring method for distinguished point based change, it is characterized in that, step is:

Step 1, by video probe, with Fixed Time Interval, continuous picture or lasting capture video are taken to certain road, when there being mobile object to enter in the scene of video probe shooting, the feature of mobile object is identified, extract current shooting to picture or current video frame on this feature record the coordinate (x of its corresponding pixel N on photo current or frame of video ₁, y ₁), and record current time t ₁;

Step 2, after a Preset Time, extract current shooting to picture or current video frame on same characteristic features record the coordinate (x of its corresponding pixel M on photo current or frame of video ₂, y ₂), and record current time t ₂;

Step 3, the size making picture or frame of video are m × n, and pixel is of a size of a × b, calculate the speed V of mobile object, wherein, T=t ₂-t ₁, A is the coordinate points corresponding to video probe subpoint on the ground on picture or frame of video, then have:

$\mathrm{AN}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}+\mathrm{arctg}[(\frac{n}{2}-x_1)\×a]/{\mathrm{DE}}^{\′}\};$

$\mathrm{AM}=\mathrm{AD}\×\mathrm{tg}\{\mathrm{arctg}\frac{\mathrm{AB}}{\mathrm{AD}}+\mathrm{arctg}\frac{B^{\′}{E}^{\′}}{{\mathrm{DE}}^{\′}}-\mathrm{arctg}[(\frac{n}{2}-x_2)\×a]/{\mathrm{DE}}^{\′}\},$ Wherein, AD is the vertical height that video probe is installed, and B publishes picture the lower boundary of picture and the intersection point of perpendicular captured by video probe, the lens focus that DE ' is video probe.

2. the video frequency speed-measuring method of a kind of distinguished point based change as claimed in claim 1, it is characterized in that, the feature of described mobile object is car plate or car beacon light.