Calibration device, range-finding system including the calibration device and stereo camera, and vehicle mounting the range-finding system

• US 9,148,657 B2
• Filed: 03/13/2013
• Issued: 09/29/2015
• Est. Priority Date: 03/21/2012
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Aoki, Shin
• Primary Examiner(s): Torrente, Richard
• Assistant Examiner(s): Suh, Joseph
• Application Number:
  US13/798,425
• Publication Number:
  US 20130250068A1
• Time in Patent Office: 930 Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/10021 Stereoscopic video; Stereoscopic image sequence
• CPC Class Codes: G06T 2207/30261 Obstacle
• CPC Class Codes: G06T 7/85 Stereo camera calibration
• CPC Class Codes: H04N 17/002 for television cameras

Abstract

A calibration device for calibrating ranges obtained by a range-finding system includes an image acquisition unit to receive inputs of two reference images captured by a reference imaging device at two locations and multiple items of parallax data from the parallax calculator. The calibration device includes a feature point search unit to search for multiple reference-feature points common to the two reference images, and a coordinate converter to convert coordinates of the two items of parallax data based on the multiple feature points and the multiple corresponding points. The calibration device includes a correction value calculator to calculate a correction value to correct the range measured by the range finding system, based on a converted parallax from the coordinate converter.

Claims

1. A calibration device for calibrating ranges obtained by a range-finding system connected to a reference imaging device, a comparison imaging device, and a parallax calculator, the reference imaging device being configured to capture at least two reference images at two locations, the comparison imaging device being configured to capture at least two comparison images at the two locations, the calibration device comprising:

an image acquisition unit configured to receive the at least two reference images and multiple items of parallax data from the parallax calculator, the items of parallax data being calculated based on multiple feature points in the at least two reference images and multiple corresponding points in the at least two comparison images correlated to the feature points in the at least two reference images;

a feature point search unit configured to, for each of the reference-feature points between the at least two reference images, search for multiple reference-feature points common to the at least two reference images;

a coordinate converter configured to convert coordinates of the items of parallax data to generate converted parallax data based on the multiple feature points and the multiple corresponding points, wherein the coordinate converter includes one of a difference calculator and a ratio calculator, the difference calculator being configured to calculate a difference between inverses of pairs of the items of parallax data and generate the converted parallax data based on the calculated difference, the ratio calculator being configured to calculate a ratio between pairs of the items of parallax data and generate the converted parallax data based on the calculated ratio; and

a correction value calculator configured to calculate a correction value to correct the range measured by the range finding system, based on the converted parallax data from the coordinate converter.

2. The calibration device according to claim 1, wherein the correction value calculator is configured to approximate the converted parallax data to a straight line, and calculate the correction value based on a position of the straight line.

3. A range-finding system that measures distance, comprising:

a reference imaging device configured to capture at least two reference images at two locations;

a comparison imaging device configured to capture at least two comparison images at the two locations;

a parallax calculator configured to calculate multiple items of parallax data; and

a calibration device configured to calibrate a range measured by the range-finding system,

the calibration device comprising;

an image acquisition unit configured to receive the at least two reference images and the multiple items of parallax data, the items of parallax data being calculated based on multiple feature points in the at least two reference images and multiple corresponding points in the at least two comparison images correlated to the feature points in the at least two reference images;

a feature point search unit configured to search for multiple reference-feature points common to the at least two reference images;

a coordinate converter configured to, for each of the reference-feature points between the at least two reference images, convert coordinates of the items of parallax data to generate converted parallax data based on the multiple feature points and the multiple corresponding points, wherein the coordinate converter includes one of a difference calculator and a ratio calculator, the difference calculator being configured to calculate a difference between inverses of pairs of the items of parallax data and generate the converted parallax data based on the calculated difference, the ratio calculator being configured to calculate a ratio between pairs of the items of parallax data and generate the converted parallax data based on the calculated ratio; and

a correction value calculator configured to calculate a correction value to correct the range measured by the range finding system, based on converted parallax data from the coordinate converter.

4. A vehicle mounting the range-finding system of claim 3.