Extended Reference Imaging for Wide-Field Depth Mapping
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Solution Overview
Problem
Existing depth mapping systems face challenges in accurately computing depth coordinates in peripheral areas of the field of view due to insufficient overlap between the projector's and camera's fields of view, particularly when the projection axis is angled, leading to incomplete reference images and distorted patterns.
Innovation Solution
The creation of an extended reference image by combining multiple reference images captured at different distances, including both central and peripheral parts of the pattern, using transformations to align and stitch these images, thereby expanding the usable field of view for depth mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single reference image is used for depth mapping, then the device complexity is low, but the field of view coverage is limited and depth accuracy in peripheral areas deteriorates
Solution Approach 1:
The reference image is segmented into multiple portions (first reference image portion, second reference image portion, third reference image portion) captured at different distances. Each portion covers a specific depth range, and they are combined to form a complete extended reference image that covers the entire field of view, resolving the contradiction between coverage area and processing complexity.
Solution Approach 2:
The solution transitions from a two-dimensional reference image to a three-dimensional extended reference image by adding the depth dimension. Multiple reference images are captured at different distances (first distance, second distance, third distance) and combined along the depth axis, creating a volumetric reference structure that enables accurate depth mapping across the entire field of view.
2Area of stationary object
If the camera axis is offset from the projection axis, then the field of view is expanded, but the overlap between reference images at different distances decreases
Solution Approach 1:
The system performs preliminary actions by capturing multiple reference images at different distances before actual depth mapping. The first reference image is captured at a first distance, the second at a second distance, and the third at a third distance. This preliminary capture of multiple perspectives ensures sufficient pattern overlap is achieved, enabling reliable matching even with camera-axis offset.
Solution Approach 2:
The solution changes the parameter of reference image capture distance. Instead of using a single reference distance, the system captures reference images at multiple distances (first distance, second distance, third distance) to create an extended reference image that maintains pattern matching reliability across the offset field of view.
3Measurement precision
If multiple reference images at different distances are captured, then the extended reference image coverage is improved, but the processing time and computational complexity increase
Solution Approach 1:
The processing is segmented into distinct stages: capturing the first reference image at the first distance, capturing the second reference image at the second distance, capturing the third reference image at the third distance, and then combining them. This segmentation allows for efficient processing of each reference image portion separately before integration, reducing overall processing time while maintaining depth mapping precision.
Solution Approach 2:
Multiple reference images captured at different distances are merged into a single extended reference image. The first reference image portion, second reference image portion, and third reference image portion are combined through image processing operations to create a comprehensive reference structure that enables accurate depth mapping across the entire field of view without requiring separate processing for each distance.
Data Source
AI summary
A method for depth mapping includes providing a depth mapping device comprising a projector, which is configured to project a pattern of optical radiation onto a target area over a first field of view about a projection axis, and a camera, which is configured to capture images of the target area within a second field of view, narrower than the first field of view, about a camera axis, which is offset transversely relative to the projection axis. The projector projects the pattern onto first and second planes at first and second distances from the camera, and the camera captures first and second reference images containing first and second parts of the pattern on the first and second planes, respectively. The first and second reference images are combined to produce an extended reference image including both the first and second parts of the pattern.