Monocular Depth Calibration Using Local Regression Planes

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Solution Overview

Problem

Existing depth estimation techniques using monocular cameras require manual calibration or additional equipment, leading to high effort and cost, and result in inaccurate depth estimation.

Innovation Solution

A depth estimation apparatus and method that calculates a calibration value for each partial region of an image based on the camera's installation position relative to horizontal or vertical planes, using regression planes to adjust depth estimates without manual work or additional equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual calibration work or additional equipment is used to ensure depth estimation accuracy, then measurement precision is improved, but device complexity and ease of operation deteriorate

Engineering Contradiction:
Improvedepth estimation accuracyVSAvoidcalibration equipment requirement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs self-calibration by automatically detecting reflection planes in the captured image and computing calibration values without requiring manual intervention or additional calibration equipment. The camera system uses its own captured image data to calibrate depth estimates, making the system self-sufficient.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical calibration processes with automated computational methods. Instead of physically positioning reference charts or using specialized calibration equipment, the system uses image processing algorithms to detect reflection planes and calculate calibration values automatically.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If manual calibration work is performed to achieve accurate depth estimation, then measurement precision is improved, but loss of time increases

Engineering Contradiction:
Improvedepth estimation accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs calibration automatically as part of the normal depth estimation process rather than requiring a separate preliminary calibration step. The calibration values are computed on-demand using the current image data, eliminating the need for time-consuming manual calibration procedures before actual measurement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The automatic self-calibration process eliminates the need for manual calibration operations, allowing the system to perform both calibration and depth estimation in a single integrated workflow, thereby significantly reducing the time required.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If retraining machine learning model parameters is performed for calibration, then measurement precision is improved, but use of energy and productivity deteriorate

Engineering Contradiction:
Improvedepth estimation accuracyVSAvoidcomputational energy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Instead of retraining the entire machine learning model parameters globally, the system computes local calibration values specific to each image or scene based on detected reflection planes. This localized approach adjusts depth estimates for current conditions without the heavy computational cost of full model retraining.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes approach from modifying model parameters (retraining) to adjusting calibration values derived from image analysis. This allows adaptation to different scenes and camera conditions through simple parameter adjustments rather than energy-intensive model retraining.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12620132B2Depth estimation apparatus, calibration method, and non-transitory computer readable recording medium
Publication Date: 2026.05.05 TOYOTA JIDOSHA KK
  • US12620132B2 patent drawing
  • US12620132B2 patent drawing
  • US12620132B2 patent drawing

AI summary

A depth estimation apparatus executes a first process of calculating a calibration value for an estimated depth and a second process of calibrating the estimated depth based on the calibration value. The first process includes: specifying a plane area in the image in which a horizontal plane or vertical plane is reflected; setting a plurality of partial regions in the image; calculating a regression plane representing the horizontal plane or the vertical plane for each partial region; and calculating the calibration for each partial region by comparing an installation position of the camera with a position of the camera with respect to the regression plane. The second process includes calibrating the estimated depth for each partial region based on the calibration value corresponding to each partial region.