Tiled Mipmap Clipmap Rendering for Seamless Detail Transitions
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Solution Overview
Problem
Existing mipmap technologies require significant memory and processing resources, especially when dealing with large graphic datasets, and suffer from 'popping' effects and vertical gaps due to non-coincident tile boundaries at different levels of detail, which hinder efficient rendering and data processing.
Innovation Solution
A mipmap is structured with graphic data arrays divided into tiles by a grid, where each tile block at one level of detail is coextensive with a single tile at the next lower level, allowing for efficient clipmapping, reduced processing requirements, and seamless transitions between levels of detail, using local tile coordinates for precise rendering and sparse population of data at higher levels to minimize storage needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a complete mipmap is stored in memory to enable real-time rendering of large graphic datasets, then rendering quality and level of detail are improved, but memory usage and data processing requirements increase significantly
Solution Approach 1:
The patent divides the complete mipmap into multiple discrete tiles organized in a hierarchical structure across different levels of detail. Instead of loading entire mipmap levels into memory, only selected tiles at each level are loaded based on the current view frustum and distance criteria. This segmentation allows the system to maintain high rendering quality when needed while dramatically reducing memory usage by loading only necessary portions of the data.
Solution Approach 2:
The patent implements a nested tile structure where tiles at higher levels of detail are hierarchically contained within tiles at lower levels. Each tile contains references to its child tiles at the next level, creating a nested organization. This allows the system to efficiently manage memory by loading parent tiles and selectively loading child tiles only when the viewer approaches that region, maintaining rendering quality progressively as the user moves closer to features of interest.
2Productivity
If tiles from different mipmap levels are combined for rendering, then data processing requirements are reduced, but tile boundary misalignment causes popping effects and image continuity problems
Solution Approach 1:
The patent introduces asymmetric offset values for tiles at different hierarchical levels. Each tile level has an associated offset that adjusts the tile boundaries to ensure proper alignment when combining tiles from different levels. This asymmetric adjustment compensates for the natural misalignment that would occur in a regular grid structure, eliminating popping effects and maintaining image continuity while allowing the system to efficiently combine tiles from multiple levels for rendering.
3Measurement precision
If the highest level of detail uses very large images (e.g., Earth map at 1m resolution), then rendering precision is improved, but memory requirements and access time increase due to larger memory size
Solution Approach 1:
The patent extracts and loads only the specific tiles currently visible in the view frustum into memory, rather than loading entire high-resolution mipmap levels. When the viewer is far from a region, only low-resolution parent tiles are loaded. As the viewer approaches, child tiles at higher resolutions are extracted and loaded into memory. This selective extraction maintains high rendering precision for visible regions while keeping memory usage and access times manageable by excluding irrelevant high-resolution data.
4Productivity
If discrete tiles are used to simplify memory updating, then memory management efficiency is improved, but non-coincident tile boundaries at different levels create vertical gaps and require cutting and pasting operations
Solution Approach 1:
The patent applies local quality adjustments by introducing offset values specific to each tile level and position in the hierarchy. Rather than using a uniform tile grid across all levels, each tile's boundaries are locally adjusted based on its hierarchical position and the offsets associated with its level. This local customization ensures that tile boundaries align properly when tiles from different levels are combined, eliminating the need for complex cutting and pasting operations while maintaining efficient memory management through the discrete tile structure.
Data Source
AI summary
The present invention relates to a computer-readable data storage medium comprising a graphic dataset in the form of a tiled mipmap 101, and to a method of extracting from said computer-readable data storage medium to a computer memory a subset of said mipmap 101 in the form of a clipmap 109. The present invention relates also to a computer memory containing such a clipmap 109, as well as to a method of rendering said clipmap 109 in a computer system. At each level of detail of the mipmap but the lowest, a tile block 105 formed by a discrete plurality of tiles 104 is coextensive with a whole single tile 104 at the next lower level of detail of the tiled mipmap 101.