Compositing Instructions for Z-Band Transparency Groups
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Solution Overview
Problem
Existing methods for rendering graphical objects struggle to efficiently determine obscurance properties when objects span multiple z-order bands, leading to difficulties in accurately determining transparency characteristics and generating optimal compositing instructions.
Innovation Solution
A method that identifies transparency groups spanning multiple z-order bands, changes processing flags for objects within these groups, and produces compositing instructions by determining contributing objects through an obscurance test, ensuring accurate rendering by considering the influence of objects across different bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If objects are partitioned into multiple z-ordered batches (z-bands), then processing efficiency is improved by handling objects in manageable groups, but the ability to efficiently determine obscurance properties deteriorates because obscurance depends on objects in separate batches
Solution Approach 1:
The patent applies preliminary action by processing objects in reverse z-order (from highest to lowest band) and pre-determining obscurance properties before final rendering. By processing higher bands first and marking objects that need below processing, the system prepares obscurance information in advance, allowing efficient determination when merging bands later without requiring full reprocessing of all objects.
2Reliability
If transparency groups span multiple z-bands, then accurate transparency characteristics can be maintained, but processing complexity increases due to the need to track objects across bands
Solution Approach 1:
The patent applies segmentation by dividing objects into z-bands while maintaining transparency group integrity through special handling of groups that span multiple bands. Objects are segmented by their z-band location, but transparency groups are tracked as logical units that may cross band boundaries. This allows the system to process objects in manageable segments while preserving the logical coherence of transparency groups through the need-below flagging mechanism.
Solution Approach 2:
The patent uses the need-below flag as an intermediary mechanism to track transparency group relationships across z-bands. This flag acts as a mediator that carries information about whether an object should have objects below it processed, enabling the system to maintain transparency characteristics without requiring direct complex tracking of all objects across multiple bands.
3Measurement precision
If all objects in a transparency group are processed to determine obscurance, then accurate transparency properties are achieved, but redundant processing occurs when objects are in different z-bands
Solution Approach 1:
The patent applies preliminary action by processing objects in reverse z-order and pre-determining which objects need below processing before final rendering. By processing higher bands first and setting the need-below flag, the system eliminates redundant processing of objects that will be completely obscured by higher bands, while still accurately determining transparency properties when needed.
Solution Approach 2:
The patent applies partial action by processing only the necessary portions of transparency groups across z-bands. Instead of processing all objects in a transparency group regardless of their z-band location, the system processes objects selectively based on their band position and the need-below flags, avoiding redundant processing of objects that will be obscured by higher bands while maintaining accurate transparency determination.
Data Source
AI summary
A method for producing a set of compositing instructions to render a region of a page receives a plurality of objects partitioned into at least two z-order bands, the received objects being associated with at least one transparency group that spans at least two bands. A transparency characteristic for at least one object within a z-order band is established. The method identifies a transparency group in the one band which is active in at least one other band and contains at least one object active in the region, determines contributing objects for the region in the band using the identified transparency group, the determination being performed by at least interpreting a change of the transparency characteristic of at least one object in the band, and produces a set of compositing instructions to render the region using the determined contributing objects.