3D Contour Detection via Depth Buffer Analysis
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Solution Overview
Problem
Conventional image processing techniques for generating cartoon-like images in three-dimensional spaces require additional processing loads due to the need for multiple models and varying outline thicknesses, which can result in unstable processing loads and visually inconsistent outlines depending on the viewpoint distance.
Innovation Solution
An image processing program and apparatus that detect contours in a three-dimensional virtual space by analyzing depth values, allowing for the generation of images without preparing additional three-dimensional objects and maintaining consistent outline thickness regardless of viewpoint distance, using a method that selects reference pixels to determine contour pixels based on depth value differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple models (basic model and enlarged model) are used to draw contours, then contour detection capability is improved, but processing load increases
Solution Approach 1:
The patent extracts only the necessary depth information from the three-dimensional space and uses it to detect contours directly in the rendered image. Instead of using multiple three-dimensional models, the invention extracts contour information from the depth buffer after a single model rendering, thereby reducing processing load while maintaining contour detection capability
Solution Approach 2:
The patent uses the depth buffer (Z-buffer) as a copy of depth information that already exists during normal rendering. By reusing this depth buffer data, the system can detect contours without requiring additional three-dimensional models or extra rendering passes, thus avoiding increased processing load
2Adaptability or versatility
If the distance from viewpoint to model varies, then three-dimensional image processing flexibility is improved, but contour thickness consistency deteriorates
Solution Approach 1:
The patent changes the parameter used for contour detection from spatial distance to depth buffer value differences. By detecting contours based on abrupt changes in depth values rather than fixed spatial distances, the system maintains consistent contour thickness across varying viewpoint distances, as the depth buffer naturally encodes the relative depth relationships independent of camera position
3Manufacturing precision
If the number of polygons in a model increases, then image processing quality is improved, but processing load increases
Solution Approach 1:
The patent makes the depth buffer serve multiple purposes: it performs its primary function of hidden surface removal during rendering and simultaneously provides the data needed for contour detection. This self-service approach allows high-quality rendering with complex polygons without additional processing load, as the contour detection reuses the depth information already computed during rendering
Data Source
AI summary
A game apparatus generates an image of a three-dimensional virtual space as viewed from a predetermined viewpoint, an object being provided in the three-dimensional virtual space. Next, the game apparatus obtains a depth value (Z value) indicating a depth from the viewpoint in a line-of-sight direction in the three-dimensional virtual space for each pixel of the image. Further, the game apparatus detects a pixel corresponding to a contour of the object based on the depth value. Specifically, a plurality of pixels are specified as reference pixels. It is determined whether or not a pixel of interest corresponds to a contour, based on a change level of differences in depth value between the pixel of interest and the reference pixels.