Arrow Pictogram Trajectory Extraction Using Skeleton Warping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for extracting trajectories from arrow pictograms, which are commonly used in direction signs but lack effective methods for trajectory extraction.
Innovation Solution
A computer-implemented method that involves acquiring a binary image of an arrow, extracting its skeleton, splitting it into bones, extending each bone to reach the arrow border, warping the extended bones and the binary image into straight lines using a thin plate spline, selecting a center component from the warped image, computing symmetric errors, and choosing the bone with the lowest symmetric error as the arrow trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If skeleton extraction and bone splitting are performed on arrow pictograms, then trajectory information can be obtained, but the curved or complex shape of bones makes direct trajectory extraction inaccurate
Solution Approach 1:
The patent applies thin plate spline warping to transform curved bones into straight lines. The warping process creates a nonlinear coordinate transformation that adapts to the curved geometry of the bone, allowing accurate trajectory extraction even when the bone has complex curved shapes. This resolves the contradiction by introducing curvature adaptation through the warping function.
Solution Approach 2:
The patent changes the coordinate system parameters through thin plate spline warping. By transforming from the original image coordinate system to a warped coordinate system where the bone becomes straight, the method enables accurate trajectory measurement. The parameter change involves the warping control points and transformation matrix that adapt to each bone's specific geometry.
2Measurement precision
If multiple bones are extended and warped to determine trajectory, then more accurate results can be achieved, but the computational complexity and processing time increase
Solution Approach 1:
The patent segments the arrow pictogram skeleton into multiple bones and processes each bone independently through extension and warping. This segmentation allows the system to evaluate multiple candidate trajectories in parallel, selecting the one with the best symmetry metric. The segmentation approach manages complexity by breaking down the problem into smaller, independent sub-problems.
Solution Approach 2:
The patent uses a feedback mechanism where each bone's warped version is evaluated using a symmetry metric, and the bone producing the most symmetric result is selected as the trajectory. This feedback loop allows the system to iteratively refine the trajectory selection by comparing multiple candidates and choosing the optimal one based on the symmetry criterion.
3Manufacturing precision
If bones are extended to reach arrow borders and warped using thin plate spline, then the trajectory can be straightened for accurate measurement, but the warping process requires selecting optimal control points which adds processing steps
Solution Approach 1:
The patent performs preliminary actions by extending each bone to the arrow borders before warping. This extension ensures that the bone spans the entire trajectory, providing better control points for the thin plate spline warping. By preparing the bone structure in advance with proper extension, the subsequent warping process becomes more efficient and accurate.
Solution Approach 2:
The thin plate spline warping process is self-adapting to each bone's geometry. The algorithm automatically determines the optimal transformation based on the bone's shape and position, without requiring manual intervention to select control points. This self-service capability reduces processing time by eliminating manual parameter tuning while maintaining high straightening accuracy.
Data Source
AI summary
A method extracts a trajectory of an arrow in a binary image. The method extracts a skeleton of an arrow in the image and splits the skeleton into bones. For each of the bones, the method extends a bone to obtain an extended bone having both ends of the bone reaching a border of the arrow, and warps the extended bone into a straight line using a thin plate spline. For each bone, the method warps the binary image into a warped image using a thin plate spline with same parameters as the thin plate spline used to warp the extended bone into the straight line. For each bone, the method selects a component that includes a center point of the warped image, computes a symmetric error of the selected component, and selects, as the trajectory of the arrow, a bone where the selected component has the lowest symmetric error.