3D Shape Reconstruction Using Visual Hull and Surface Refinement
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Solution Overview
Problem
Existing visual hull methods for generating three-dimensional shape data often inaccurately approximate curved or concave surfaces, leading to significant errors in the resulting shape data.
Innovation Solution
An image processing apparatus and method that utilizes multiple cameras to capture images from different viewpoints, derives surface three-dimensional information, selects reliable data points, and corrects distance images to enhance accuracy, particularly for objects with complex shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the visual hull method is used to generate three-dimensional shape data, then the shape can be obtained stably and fast, but the accuracy deteriorates for curved or concave surfaces
Solution Approach 1:
The patent segments the three-dimensional shape data into two components: approximate shape data obtained by the visual hull method and surface three-dimensional information obtained by selective projection. This segmentation allows each component to address different aspects of the problem - the visual hull provides stable and fast initial shape data, while the selective projection adds detailed surface information to improve accuracy for curved and concave surfaces.
Solution Approach 2:
The patent merges the approximate shape data from the visual hull method with the surface three-dimensional information from selective projection. By combining these two data sources, the system achieves both the speed and stability of the visual hull method and the accuracy of detailed surface representation, resolving the contradiction between productivity and measurement precision.
2Ease of manufacture
If the visual hull method approximates curved or concave surfaces as flat surfaces, then the processing is simplified, but the accuracy of the three-dimensional shape data deteriorates
Solution Approach 1:
The patent segments the surface representation into flat approximate surfaces from the visual hull and detailed curved surfaces from selective projection. This allows the system to maintain simple flat surface processing where applicable while adding detailed curved surface information only where needed, balancing processing simplicity with surface accuracy.
Solution Approach 2:
The patent applies local quality by enhancing only the surface regions that require higher accuracy (curved and concave portions) through selective projection, while maintaining the simple flat surface approximation in regions where it is sufficient. This localized enhancement improves overall accuracy without unnecessarily complicating the entire processing system.
3Device complexity
If local shape information is derived from approximate shape model, then the processing is simplified, but the accuracy of distance information deteriorates for concave portions
Solution Approach 1:
The patent performs preliminary action by first obtaining approximate shape data through the visual hull method, then using this as a basis for selective projection. This preliminary step provides a stable foundation that simplifies subsequent processing while the selective projection step corrects distance information accuracy for concave portions without requiring complete redesign of the processing system.
Data Source
AI summary
An object is to obtain three-dimensional shape data with high accuracy from three-dimensional shape data representing an approximate shape of an object. Three-dimensional shape data of an object captured in a plurality of captured images whose viewpoints are different is obtained. Further, surface three-dimensional information on the object is derived based on the plurality of captured images. Then, the derived surface three-dimensional information is selected based on a distance from the shape surface of the object represented by the three-dimensional shape data.