Run-Length Stripping for River Network Skeleton Lines
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Solution Overview
Problem
Existing methods for extracting skeleton lines from complex river networks face challenges such as high memory occupation and low computational efficiency, particularly when dealing with large datasets like those from the Yangtze River Basin.
Innovation Solution
A run-length stripping method is proposed, which involves constructing an empty raster field, compressing binary raster data into run-length linked lists, and using discriminant functions to identify and strip redundant grids, ultimately converting raster data into vector form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If raster resolution is increased to improve skeleton line extraction accuracy, then measurement precision is improved, but memory occupation increases significantly
Solution Approach 1:
The patent divides the large-scale river network raster data into multiple smaller tile units for independent processing. Each tile is processed separately to extract skeleton lines, avoiding the need to load the entire high-resolution raster into memory at once. This segmentation enables high-precision extraction while controlling memory usage within acceptable limits.
Solution Approach 2:
The patent transforms the problem from direct high-resolution raster processing to a multi-scale approach. By processing at different resolution levels and progressively refining results, the method achieves high measurement precision without requiring the entire high-resolution data to be held in memory simultaneously, effectively adding a temporal/dimensional dimension to the processing workflow.
2Measurement precision
If raster resolution is increased to improve skeleton line extraction accuracy, then measurement precision is improved, but computational efficiency decreases
Solution Approach 1:
The patent segments the computational task into independent tile-based units that can be processed in parallel. Each tile undergoes skeleton line extraction independently, allowing for distributed computing and parallel processing. This segmentation maintains high extraction accuracy while significantly improving computational efficiency through parallel execution and reduced data transfer overhead.
Solution Approach 2:
The patent performs preliminary processing steps such as rasterization and tile division before the main skeleton line extraction. By preparing data in advance and organizing it into manageable tiles with predefined processing workflows, the method reduces computational overhead during the actual extraction process, thereby improving overall computational efficiency without compromising accuracy.
3Productivity
If vector method is used for skeleton line extraction, then computational efficiency is improved, but manufacturing precision worsens due to sawtooth artifacts
Solution Approach 1:
The patent segments the river network into tile units and processes each independently using raster-based thinning algorithms. This segmentation allows the use of precise raster methods on smaller domains while maintaining overall computational efficiency. The local processing ensures smooth skeleton lines without the sawtooth artifacts that plague global vector methods.
Solution Approach 2:
The patent introduces an intermediate raster representation as a mediator between the input vector river network and the final skeleton line output. The vector data is first converted to high-resolution raster, processed through precise thinning algorithms, and then converted back to vector format. This intermediate raster step acts as a mediator that preserves both computational efficiency and manufacturing precision.
4Manufacturing precision
If raster method is used for skeleton line extraction, then manufacturing precision is improved, but computational efficiency decreases due to rasterization requirement
Solution Approach 1:
The patent segments the raster processing task into independent tile units that can be processed in parallel. By dividing the large raster dataset into smaller tiles, the method reduces memory requirements and enables parallel computation, thereby improving computational efficiency while maintaining the high manufacturing precision of raster-based methods.
Solution Approach 2:
The patent adds a spatial dimension to the processing by organizing raster data into a tile hierarchy. This multi-level spatial organization allows efficient memory management and parallel processing at different scales, reconciling the conflict between manufacturing precision and computational efficiency by operating at appropriate resolution levels for each processing stage.
Data Source
AI summary
The application relates to a run-length stripping method for generating skeleton lines of complex plain river networks, including following steps: 1. constructing an empty raster field, each raster row generates an empty run-length linked list; 2. completing raster compression on each row, and compressing the continuous grids into run-length units and inserting them into the raster row run-length linked list; 3. establishing a raster field river boundary grid search template; 4. setting two discriminant functions to judge whether a grid on a raster field is a redundant grid; 5. searching all boundary grids along a raster field boundary, and marking and stripping all redundant grids based on two discriminant functions respectively; 6. analyzing whether the boundary grid is stripped, if so, returning to continue stripping, otherwise, entering the next step; 7. converting the non-stripped grid into skeleton line data in vector form.


