Distance measurement device and distance measurement method

1. A distance measurement device comprising:

a memory; and

a processor coupled to the memory and configured to:

detect a plurality of edge lines from image data received from a camera mounted on a moving object;

select two edge lines from among the plurality of the detected edge lines;

remove the selected two edge lines from a plurality of first edge lines having a characteristic of a predetermined target object when a distance between the selected two edge lines on the lower side of the selected two edge lines is larger than a distance between the selected two edge lines on the upper side of the selected two edge lines;

identify the plurality of the first edge lines, except the removed two edge lines, that have the characteristic of the predetermined target object;

search coordinates of a second edge line located at the lowest position from among the identified plurality of first edge lines; and

measure a distance from the moving object to the predetermined target object based on the searched coordinates of the second edge line and a parameter of the camera.

2. The distance measurement device according to claim 1 ,

wherein the processor identifies, based on differential image data between past image data received from the camera and current image data received from the camera, a search region in which the predetermined target object exists, and

wherein the processor detects the plurality of edge lines from the search region included in the current image data.

3. The distance measurement device according to claim 1 ,

wherein the processor executes a process of calculating a flow amount for each of characteristic points on past image data received from the camera based on the positions of the characteristic points and positions corresponding to the characteristic points and located on current image data received from the camera,

wherein the processor identifies a region including characteristic points of which flow amounts are equal to or smaller than a certain value, and

wherein the processor detects a plurality of edge lines from the identified region.

4. The distance measurement device according to claim 1 ,

wherein the processor learns the characteristic of the predetermined target object,

wherein the processor identifies, based on the learned characteristic and the image data captured by the camera, a region in which the predetermined target object exists, and

wherein the processor detects a plurality of edge lines from the identified region.

5. A distance measurement method comprising:

detecting, by a processor, a plurality of edge lines from image data received from a camera mounted on a moving object;

selecting, by a processor, two edge lines from among the plurality of the detected edge lines;

removing, by a processor, the selected two edge lines from a plurality of first edge lines having a characteristic of a predetermined target object when a distance between the selected two edge lines on the lower side of the selected two edge lines is larger than a distance between the selected two edge lines on the upper side of the selected two edge lines;

identifying, by a processor, the plurality of the first edge lines, except the removed two edge lines, that have the characteristic of the predetermined target object;

searching, by a processor, coordinates of a second edge line located at the lowest position from among the identified plurality of first edge lines; and

measuring, by a processor, a distance from the moving object to the predetermined target object based on the searched coordinates of the second edge line and a parameter of the camera.