PEDESTRIAN-CROSSING MARKING DETECTING METHOD AND PEDESTRIAN-CROSSING MARKING DETECTING DEVICE

• US 20120148104A1
• Filed: 09/22/2010
• Published: 06/14/2012
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nanri, Takuya, Nishimura, Hirofumi
• Granted Patent: US 8,744,131 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G01C 21/3697 Output of additional, non-guidance related information, e.g. low fuel level G01C21/3679 takes precedence
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle
• CPC Class Codes: G06V 20/588 Recognition of the road, e.g. of lane markings; Recognition of the vehicle driving pattern in relation to the road

Abstract

Provided are a pedestrian-crossing marking detecting method and a pedestrian-crossing marking detecting device, wherein the existence of pedestrian crossing markings and the positions thereof can be detected accurately from within a picked up image, even when detection of the intensity edges of painted sections is difficult. In the pedestrian-crossing mark detecting device (100), a road-surface distance of a predetermined range is calculated with respect to image data picked up from the periphery of the vehicle including the road, using camera installation information or a stereo camera'"'"'s distance information, and the period of the pedestrian crossing markings is calculated on the basis of the road-surface distance of the predetermined range, and furthermore, a power of frequency is calculated using an even function and odd function of a square wave of the period as the basis function. In such a way, the existence of pedestrian crossing markings and the positions thereof can be detected accurately from within the captured image, even with pedestrian crossing markings where the paint has faded.

Claims

1. A pedestrian-crossing marking detecting device comprising:

an image data obtaining section that has a first imaging system and obtains image data on a road surface captured by the first imaging system;

a period calculating section that calculates a period of painted portions on the image data when the painted portions of a pedestrian-crossing marking are included in a calculation range of the image data, based on coordinates of the calculation range, geometric parameters of the first imaging system and predefined values of the pedestrian-crossing marking;

a frequency analyzing section that analyzes a frequency of an image intensity in the calculation range and calculates a frequency power distribution, based on the basis function in which the integral multiple of the period of the painted portions is assumed as one period;

an area detecting section that extracts a coordinate point at which a power level in the frequency power distribution is larger than a predetermined threshold from the calculation range, and detects an area in which the coordinate point is present as a pedestrian-crossing marking area; and

a position outputting section that outputs coordinate data on the pedestrian-crossing marking area in the image data.

2. The pedestrian-crossing marking detecting device according to claim 1, wherein the period calculating section comprises:

a memory section that previously stores geometric parameters of the first imaging system and predefined values of the pedestrian-crossing marking therein;

a parameter obtaining section that obtains the coordinates of the calculation range from the image data obtaining section, and obtains the geometric parameters of the first imaging system and the predefined values of the pedestrian-crossing marking from the memory section; and

a calculating section that calculates a period of the painted portions, based on the coordinates of the calculation range, the geometric parameters of the first imaging system, and the predefined values of the pedestrian-crossing marking.

3. The pedestrian-crossing marking detecting device according to claim 1, wherein the period calculating section comprises:

a memory section that previously stores the geometric parameters of the first imaging system and the predefine values of the pedestrian-crossing marking therein;

a parameter obtaining section that obtains the coordinates of the calculation range from the image data obtaining section, and obtains the geometric parameters of the first imaging system and the predefined values of the pedestrian-crossing marking from the memory section;

a rotation detecting section that has a sensor for detecting a change in angle speed, and when a change in angle speed detected by the sensor is larger than a predetermined threshold, detects a rotation of the pedestrian-crossing marking detecting device;

an angle calculating section that when a rotation of the pedestrian-crossing marking detecting device is detected, calculates a rotation angle based on a change value of the angle speed detected by the sensor; and

a calculating section that calculates a period of the painted portions, based on the coordinates of the calculation range, the geometric parameters of the first imaging system, the predefined values of the pedestrian-crossing marking, and the rotation angle.

4. The pedestrian-crossing marking detecting device according to claim 1, further comprising a distance calculating section that calculates a distance in a real space between the first imaging system and a road surface indicated in the calculation range as distance data, based on the coordinates of the calculation range included in the image data and the geometric parameters of the first imaging system,

wherein the period calculating section calculates a period of painted portions when the painted portions of a pedestrian-crossing marking are included in the calculation range, based on the distance data and the predefined values of the pedestrian-crossing marking, and

the position outputting section outputs coordinate data on the pedestrian-crossing marking area in the image data, and the distance data.

5. The pedestrian-crossing marking detecting device according to claim 1, further comprising a stereo matching section and a distance calculating section,

wherein the image data obtaining section further has a second imaging system, and obtains target image data in which a road surface is captured by the first imaging system and reference image data in which the road surface is captured by the second imaging system,

the stereo matching section calculates an evaluation value distribution indicating a difference in image intensity between a target point of the target image data and multiple search points of the reference image data, and calculates a distance in a real space between the first imaging system and the road surface captured in the target image data as first distance data based on a disparity calculated based on the evaluation value distribution, a focal length of the first imaging system, and a distance between the first imaging system and the second imaging system,

the distance calculating section calculates 3D voxel data of the target image data based on the first distance data, and calculates a distance in a real space between the first imaging system and the road surface indicated in the calculation range included in the target image data, as second distance data, based on the 3D voxel data,

the period calculating section calculates a period of painted portions when the painted portions of a pedestrian-crossing marking are included in the calculation range, based on the second distance data and the predefined values of the pedestrian-crossing marking, and the position outputting section outputs coordinate data on the pedestrian-crossing marking area in the target image data, and the second distance data.

6. The pedestrian-crossing marking detecting device according to any of claims 1, 4 and 5, wherein the geometric parameters of the first imaging system and the second imaging system are an installation pitch angle, an installation height, a focal length and a pixel pitch of the imaging systems.

7. The pedestrian-crossing marking detecting device according to any of claims 1, 4 and 5, wherein the frequency analyzing section analyzes a frequency based on the basis function in which one period is twice as much as the period of the painted portions.

8. The pedestrian-crossing marking detecting device according to any one of claims 1, 4 and 5, wherein the area detecting section controls the predetermined threshold based on an illumination of a surrounding area of the vehicle.

9. A pedestrian-crossing marking detecting method comprising the steps of:

obtaining image data on a road surface captured by an imaging system;

calculating a period of painted portions when the painted portions of a pedestrian-crossing marking are included in a calculation range of the image data, based on coordinates of the calculation range, geometric parameters of the imaging system, and predefined values of the pedestrian-crossing marking;

performing a frequency analysis of an image intensity in the calculation range and calculating a frequency power distribution, based on the basis function in which the integral multiple of the period of the painted portions is assumed as one period;

extracting a coordinate point at which a power level in the frequency power distribution is larger than a predetermined threshold from the calculation range, and detecting an area in which the coordinate point is present as a pedestrian-crossing marking area; and

outputting coordinate data on the pedestrian-crossing marking area in the image data.

10. The pedestrian-crossing marking detecting method according to claim 9, wherein the geometric parameters of the imaging system include an installation pitch angle, an installation height, a focal length, and a pixel pitch of the imaging system.