Direct Volume Haptic Rendering for Volumetric Data
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Solution Overview
Problem
Current virtual reality systems face challenges in providing realistic, real-time haptic feedback for interacting with volumetric data, particularly in simulating the elastic deformation of tissues and organs, which is computationally expensive and limited to simple models.
Innovation Solution
The system calculates resistive forces based on physical characteristics of objects in a virtual reality environment using a force model parameterized by coefficients, allowing for direct haptic feedback without preprocessing steps, and uses voxel density values to determine resistive forces for interactive visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If finite element methods are used to model deformable objects, then realistic haptic feedback simulation is achieved, but computational cost becomes excessively high and real-time performance is compromised
Solution Approach 1:
The patent extracts only the essential physical characteristics (density, elasticity coefficients) needed for haptic feedback from the complex volumetric data, rather than processing the entire detailed geometric model. This allows realistic haptic simulation without the computational burden of complete finite element analysis.
Solution Approach 2:
The invention changes the approach from geometric parameter-based simulation to density/coefficiency parameter-based simulation. By using transfer functions that map voxel density values to haptic coefficients, the system achieves real-time performance while maintaining physical realism.
2Reliability
If finite element methods are used to simulate complex anatomical structures, then simulation accuracy is improved, but the system can only handle relatively simple models
Solution Approach 1:
The patent creates a universal haptic rendering approach that works with any volumetric data without requiring preprocessing or segmentation. The transfer function methodology can handle diverse anatomical structures (organs, tissues, bones) using the same density-to-coefficient mapping, making the system highly adaptable.
Solution Approach 2:
Instead of creating geometric representations of anatomical structures, the system uses direct volumetric sampling with density-based parameter extraction. This copying approach preserves the essential physical properties needed for haptic feedback while avoiding the complexity of geometric modeling.
3Reliability
If finite element methods are used for haptic feedback, then realistic tissue deformation is achieved, but preprocessing steps are required to segment volumetric data
Solution Approach 1:
The patent eliminates the need for manual segmentation by using automatic density-based classification. The transfer function automatically assigns haptic coefficients based on voxel density values, seamlessly handling different tissue types without requiring preprocessing to separate anatomical structures.
Solution Approach 2:
The volumetric data itself provides all necessary information for haptic feedback through its density values. The system is self-sufficient, using the inherent physical properties of the scanned data to generate haptic parameters without external preprocessing or manual intervention.
4Measurement precision
If detailed geometric representations are created from volumetric data, then visualization quality is improved, but computational processing time increases
Solution Approach 1:
The patent performs only the necessary computation for haptic feedback (density sampling and coefficient mapping) without creating complete geometric representations. This partial action approach provides sufficient visualization quality for interaction while minimizing processing time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-performance, real-time haptic feedback simulations that can handle complex anatomical structures, providing an immersive experience without the need for geometric preprocessing, allowing users to interact with volumetric data in a more realistic and efficient manner.
Implementation Method 1
A resistance force is calculated using a spring mass model parameterized by one or more coefficients corresponding to the object
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method comprises presenting a visualization of a plurality of anatomical objects in a user's display and monitoring a position of a haptic feedback device operated by the user with respect to the visualization. Based on the monitored position, it is determined that the haptic feedback device is being used to virtually touch a particular object in the visualization. A resistance force for the particular object is calculated using a force model parameterized by one or more coefficients corresponding to the object. This resistance force is used to provide a haptic feedback with the haptic feedback device.