Occlusion Estimation Using Depth Buffer Comparison
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Solution Overview
Problem
Existing methods for estimating occlusion in virtual environments, such as the z-buffer algorithm, require calculating attributes for all surface fragments, even if only a portion is visible, leading to inefficient calculation power and time, especially in dynamic environments where real-time visibility is needed.
Innovation Solution
The proposed solution utilizes a method with multiple buffer memories (render buffers and a z-buffer) to store depth and attribute information, allowing for efficient comparison and storage of only visible fragments' attributes, reducing unnecessary calculations by using render targets alternately and updating buffers to reflect occlusion information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the z-buffer algorithm is used to manage visibility in a virtual environment, then the visibility of objects can be determined, but the calculation time and power increase significantly because all surface fragments must be processed even when only a portion is visible
Solution Approach 1:
The patent applies preliminary action by performing a depth buffer initialization and comparison pass before the main rendering pass. The depth buffer is pre-filled with depth values from depth texture samples, and occlusion status is pre-determined for each pixel. This preliminary processing enables the main rendering pass to skip invisible fragments, significantly reducing calculation time while maintaining accurate visibility determination.
Solution Approach 2:
The patent implements partial action by processing only the visible portions of surface fragments. Through the depth buffer comparison and occlusion testing mechanism, the system identifies and processes only those surface fragments that are actually visible from the camera viewpoint, rather than processing all fragments. This selective processing reduces computational workload while maintaining rendering quality.
2Measurement precision
If all surface fragments are processed to ensure complete visibility information, then accurate occlusion estimation is achieved, but calculation power and time are wasted on invisible fragments
Solution Approach 1:
The system performs preliminary depth buffer initialization and occlusion status determination before processing surface fragments. By pre-computing which pixels are occluded based on depth buffer comparisons, the system can skip energy-intensive surface fragment processing for invisible portions, thereby reducing overall power consumption while maintaining accurate occlusion estimation for visible fragments.
Solution Approach 2:
The patent extracts and separates the occlusion determination function from the surface fragment processing function. The depth buffer stores only depth information, while the occlusion status is determined separately through comparison operations. This extraction allows the system to identify invisible fragments without processing their surface attributes, reducing computational power requirements while maintaining estimation accuracy.
3Loss of time
If advanced techniques like hierarchical z-pyramid are used to reduce calculations, then calculation time is reduced, but the complexity of the system increases and prior processing is required which is unsuitable for dynamic environments
Solution Approach 1:
The patent extracts the occlusion determination logic from complex hierarchical structures and implements it through a simplified depth buffer comparison mechanism. Instead of using a hierarchical z-pyramid with multiple processing levels, the system uses a single depth buffer initialized with depth texture samples and performs direct pixel-wise comparisons. This extraction simplifies the system architecture while maintaining efficient calculation performance for dynamic environments.
Solution Approach 2:
The patent changes the parameter representation by storing depth information in a standard depth buffer format compatible with existing graphics hardware. Rather than implementing a hierarchical z-pyramid structure, the system uses conventional depth buffer operations with optimized initialization and comparison routines. This parameter change approach reduces system complexity while achieving similar or better performance for real-time dynamic rendering.
Data Source
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AI summary
The invention relates to a method for estimation of occlusion in a virtual environment comprising at least two objects and observed from a viewpoint. In order to minimize the required calculation time, the method comprises steps for: estimating a second item of information representative of the distance separating a second fragment of a second object from said viewpoint according to an observation direction, comparing of said second item of information with a first item of information representative of the distance separating a first fragment of a first object from said viewpoint according to said observation direction and stored in a first buffer memory: · if the second item of information is less than the first item of information, the estimation of a third item of information representative of attributes associated with the second fragment, storage of the second item of information in a second buffer memory and storage of the third item of information in a third buffer memory, ° if the second item of information is greater than the first item of information, storage of the first item of information in the second buffer memory.