CN101033966A - Photography measurement method of scene of a traffic accident - Google Patents

Abstract

A photogrammetric method for a traffic accident scene, the steps are as follows: ①Use calibration objects to calibrate the photogrammetry, and assemble the disassembled calibration objects; ②Use the coordinate origins of four identical calibration objects as vertices to form a rectangle to form a calibration system , to realize the photogrammetric calibration of the traffic accident scene. ③ Use the camera to take a group of two-dimensional photos of the traffic accident scene where the calibration system is installed according to the clockwise moving direction and shooting angle. ④ Import the captured photos into the computer, select the points to be measured, obtain the image space coordinates, obtain the object space coordinates of the points to be measured, and use the obtained actual space coordinates to draw the traffic accident scene through geometric calculation information required for the graph. The invention effectively improves the time for on-site investigation of traffic accidents, improves the accuracy of data measurement at the accident site, and can meet the actual needs of rapid handling of traffic accidents.

Description

Photogrammetric Method of Traffic Accident Scene

technical field

The invention relates to a method in the technical field of transportation, in particular to a photogrammetry method for a traffic accident scene.

Background technique

In order to improve the accuracy of traffic accident identification, it is necessary to carefully investigate useful information such as vehicle parking positions, tire impressions and drag marks, road scratches, oil stains, debris, and indentations outside the road at the accident scene. Traditional traffic accident on-site survey work is completed by human eyes, hand touch, tape measurement, and manual drawing. This measurement method is not accurate, takes up a long time, and is prone to missing information, which cannot provide sufficient information for accident analysts. information. As the traffic becomes more and more busy, it is necessary to measure the traffic accident scene quickly and accurately. Therefore, experts from all over the world are working hard to find new technologies for traffic accident scene survey.

The document retrieval of prior art finds, the people such as Cooner of Texas Transportation Institute (Dezhou Traffic Research Institute) published a technical report "Use ofPhotogrammetry for Investigation of Traffic Incident Scenes" in October, 2000 ("Photogrammetry in Traffic Incident Scenes") Use in Site Investigation") (Report No: TX-99/4907-2) studies the application of photogrammetry technology in traffic accident investigation. Cooner pointed out in the article that photogrammetry technology in traffic accident investigation is mainly in the trial stage, but in order to obtain accurate and comprehensive measurement data, on-site calibration and shooting methods play a great role. At present, when domestic and foreign experts use photogrammetry to investigate traffic accidents, they mainly place more than six calibration points (reference points with known actual spatial positions) on the scene for calibration. Although compared with the traditional measurement method, the photogrammetry method can greatly shorten the investigation time of traffic accidents, but it will take a lot of time to reasonably arrange the calibration points and measure their actual spatial position coordinates, which still cannot meet the needs of traffic accidents. processing requirements.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the existing photogrammetry technology in the application of traffic accident scene survey, and provide a photogrammetry method for traffic accident scene, so that it can quickly calibrate and shoot with the traffic accident scene to meet the actual needs .

The present invention is realized through the following technical solutions, and concrete steps are as follows:

① For the convenience of portability, the calibration object used in the present invention is designed to be a detachable structure. Therefore, before the calibration of photogrammetry, the calibration object must be assembled first.

The calibration object is a detachable structure, for convenience, the calibration object is disassembled and carried. The calibration object is composed of a sleeve base and three shafts with a length of 80 cm. Among them, the sleeve base is composed of three square hollow tubes with a length of 20 cm and perpendicular to each other; when calibrating the scene of a traffic accident, insert the three shafts into the sleeve The base can then be assembled into a calibration object. The three axes of the calibration object represent the X, Y and Z axes of the space coordinates of the object respectively, and the scales are marked with yellow and black colors every 20cm on the axes.

② In order to solve the shortcomings of difficult selection of calibration points (reference points with known spatial coordinate values) in photogrammetry and the time-consuming measurement of the coordinates of calibration points, it is necessary to place them in a reasonable position to form a calibration system to realize the detection of traffic accidents. On-site photogrammetry calibration.

The calibration system is a rectangular measurement area composed of four identical calibration objects, the coordinate origin of the calibration object is the apex of the rectangle, the axes of the four calibration objects are respectively on a straight line, and the area to be measured is contained in the rectangle among. After determining the relative positions of the four calibration objects, the calibration of the traffic accident scene can be completed, and more calibration points can be selected from the axis of each calibration object.

③ Use the camera to take a set of two-dimensional photos of the traffic accident scene where the calibration system is installed according to a certain moving direction and shooting angle.

The resolution of the digital camera in photogrammetry is higher than 5 million pixels. The position of the camera when shooting is taken at the back of each calibration object, and the calibration system is the shooting center. The accident scene is framed in a clockwise direction in all directions, and each photo is guaranteed to be Include at least three calibration objects; in addition, the camera should be at a vertical angle of 45° to the horizontal, and the intersection angle of the cameras between two adjacent shooting positions should be close to 90°.

④ Import the captured photos into the computer, select the points to be measured, and obtain their pixel coordinate values, establish the relationship between the image space coordinate system and the object space coordinate system (coordinates in the actual space) according to the DLT method, and use the least square method Perform iterations to obtain the object space coordinates of the points to be measured. Through the geometrical calculation of the coordinate values, information such as the length of the brake marks is finally obtained.

The present invention has the following characteristics: the calibration objects used in the present invention can be disassembled and are easy to carry; before shooting the accident scene, a calibration system that can be quickly composed of four calibration objects is used to measure the relative positions of the vertices of the four calibration objects. This can reduce the trouble caused by the placement of the calibration object, and at the same time reduce the minimum number of calibration points in general photogrammetry from 6 to 4; after the traffic accident is handled by using the present invention, the time for on-site traffic accident processing can be effectively reduced , to reduce the economic losses caused by traffic jams caused by accidents.

Description of drawings

Figure 1 Dismantled traffic accident scene survey calibration objects

Figure 2 The assembled traffic accident scene calibration object

Figure 3 Rectangular calibration system composed of calibration objects

Figure 4 Schematic diagram of traffic accident scene shooting

Figure 5 Coordinate transformation between object space coordinate system and image coordinate system

Detailed ways

Below in conjunction with accompanying drawing the embodiment of the present invention is described in detail: present embodiment is tried out in the middle of the traffic accident scene measurement of traffic police detachment of Fengxian District, Shanghai City under the premise of technical solution of the present invention, but protection scope of the present invention is not limited to following the embodiment.

①In this embodiment, first assemble the detachable calibration object. Insert the three shafts as shown in Figure 1 into the sleeve base, as shown in Figure 2, place two yellow square tubes horizontally as the horizontal plane, and the black hollow tube vertically upwards as the Z axis.

② When calibrating the traffic accident scene, as shown in Figure 3, use the coordinate origins of four identical calibration objects as vertices to form a rectangular calibration system. The axes of the four calibration objects are on a straight line, and the area to be measured is contained in a rectangle. In this way, as long as the relative positions of the four calibration objects are determined, the calibration of the traffic accident scene can be completed. More calibration points needed can be directly selected from the coordinate axes of the calibration object in the photo in the later computer processing.

③A Kodak EasyShare Z7590 digital camera was used as a tool for shooting the accident scene. The CCD/CMOS resolution of the camera is 5 million pixels, and the maximum effective resolution is 2576×1932. When shooting the accident scene, the camera should be at a vertical angle of 45° from the horizontal, and stand behind each calibration object in the rectangular calibration area as shown in Figure 4 as the position of the camera when shooting. Taking the calibration system as the shooting center, the accident scene is taken in all directions at the positions of the four calibration objects in a clockwise direction. In order to improve the accuracy of photogrammetry, the camera intersection angle between two adjacent shooting orientations is close to 90°, and it is guaranteed that each photo contains at least three calibration objects.

④ Import the captured photos into the computer, and according to the linear relationship shown in Figure 5, establish the direct linear transformation relationship between the image space coordinates and the actual object space coordinates:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 7</span>}}\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, I′=II ₀ , J′=JJ ₀ , I, J are the image space coordinates, I ₀ , J ₀ are the coordinate values of the principal point in the image space, l ₁ to l ₁₁ are direct linear transformation coefficients (DLTP) , which are functions of the camera's inner and outer orientation elements. Since the calculation does not require the initial value of the inner orientation element and the outer orientation element, it has become the most basic formula for photogrammetry using ordinary digital cameras.

Changing formula (1) into correction number equation can be transformed into formula (2):

$\left\{\begin{array}{c}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="l"\; filenames="A20071003937600081.png"\; state="\{\{state\}\}">l</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}{\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}{\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 7</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}{\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{{\mathrm{<span\; class="notranslate">\; J</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}\end{array}\right.<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them: A=l ₉ X+l ₁₀ Y+l ₁₁ Z+1 can iteratively solve formula (2) by the least square method, in order to facilitate rapid convergence, take A=1, and calculate 11 coefficients l _i of the photo The approximate value of l _i ′; Substitute l _i ′ into the calculation of A value, and then return to (1), iterate repeatedly until the value difference of A is less than the given tolerance, and calculate the 11 coefficients l _i and the object space coordinates of the point . By geometrically calculating the coordinate values of the final actual space, information such as the parking position of the braked vehicle, tire imprints and drag marks required for drawing the accident scene map can be obtained.

The method of the present invention is applied in major traffic accidents. Compared with the traditional manual measurement method, because only the coordinates of 4 calibration objects need to be measured, instead of measuring the information such as brake marks on the spot and drawing the scene map one by one, it can save 12 on average. It takes about 10 minutes, and the accuracy is 2% lower than that of traditional measurement, which can meet the application requirements of rapid investigation of traffic accident sites.

Claims (7)

1, a kind of photogrammetry method of traffic accident scene, is characterized in that, comprises the steps: ①Using calibration objects for photogrammetry calibration, first assemble the disassembled calibration objects; The calibration object is a detachable structure, the calibration object is disassembled and carried, and the calibration object is composed of a sleeve base and three shafts, wherein the sleeve base is composed of three mutually perpendicular square hollow tubes; when calibrating the traffic accident scene , insert the three axes into the base of the sleeve to assemble the calibration object, the three axes of the calibration object represent the X, Y and Z axes of the space coordinates of the object, and the scales are marked on the axes; ②Using the coordinate origins of four identical calibration objects as vertices to form a rectangle to form a calibration system to realize the calibration of photogrammetry on the scene of traffic accidents; ③ Use the camera to take a group of two-dimensional photos of the traffic accident scene where the calibration system is installed according to the clockwise moving direction and shooting angle; ④ Import the captured photos into the computer, select the points to be measured, and obtain their image space coordinates, establish the conversion relationship between the image space coordinates and the object space coordinates according to the DLT algorithm, and finally iterate through the least squares method to obtain the The object-space space coordinates of the measurement points are obtained from the actual space coordinate values, and the information required for drawing the traffic accident scene map is obtained through geometric calculation. 2. The photogrammetry-based traffic accident site investigation method according to claim 1, characterized in that, in step ①, the length of the three axes of the calibration object is 80 cm. 3. The photogrammetry-based traffic accident site investigation method according to claim 1 or 2, characterized in that in step ①, the scales are marked with two colors of yellow and black every 20cm on the three axes of the calibration object. 4. The photogrammetry-based traffic accident site investigation method according to claim 1, characterized in that, in step ①, the three square hollow tubes of the calibration object are 20 cm long. 5. The photogrammetry-based traffic accident site investigation method according to claim 1, wherein in step ②, the calibration system is a rectangular measurement area composed of four identical calibration objects, and the coordinate origin of the calibration objects is used as At the apex of the rectangle, the axes of the four calibration objects are on a straight line, and the area to be measured is included in the rectangle; after determining the relative positions of the four calibration objects, the calibration of the traffic accident scene can be completed. More calibration objects Fixed points are picked from the axis of each calibrator. 6. The photogrammetry-based traffic accident site investigation method according to claim 1, wherein in step ③, the camera position is taken behind each calibration object, and the calibration system is the shooting center, clockwise to The scene of the accident is framed in all directions, and at least three calibration objects are included in each photo; in addition, the camera should be at a vertical angle of 45° to the horizontal, and the intersection angle of the cameras between two adjacent shooting positions should be close to 90°. 7. The photogrammetry-based traffic accident site investigation method according to claim 1 or 6, characterized in that, in step ③, the camera is a digital camera with a resolution higher than 5 million pixels.

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