Camera-Based Pointer Recognition Motion Blur Compensation

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Solution Overview

Problem

Existing pointer recognition systems for large format touch screens are costly and complex, relying on sophisticated image sensors and additional hardware components, which is not feasible for inexpensive but reliable alternatives.

Innovation Solution

An interactive system with cameras and a processing structure that compensates for motion blur by generating a mean intensity profile and determining pointer type using models like erf and Butterworth, disentangling point-spread function and real pointer widths, and associating digital ink attributes, with infrared pass filters and LEDs for improved accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sophisticated image sensors and additional hardware components are used, then pointer recognition reliability is improved, but system cost and complexity increase

Engineering Contradiction:
Improvepointer recognition reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by capturing multiple video frames before final pointer type determination. The processing structure analyzes a sequence of frames to compensate for motion blur and accurately identify pointer characteristics, ensuring reliable recognition without requiring complex hardware components

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses optical copying through camera-based image capture to represent the physical pointer on the touch surface. By capturing visual information and processing it algorithmically, the system achieves reliable pointer identification without needing complex sensing hardware or additional hardware components

Inventive Principle:
Principle #26Copying

2Measurement precision

If motion blur compensation is applied, then pointer type determination accuracy is improved, but processing time increases

Engineering Contradiction:
Improvepointer type determination accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary frame capture and background image generation before actual pointer recognition. By pre-processing the touch surface environment and having multiple reference frames ready, the system can quickly compensate for motion blur during actual pointer type determination without significant processing delays

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The processing structure uses feedback from multiple video frames to refine pointer type determination. By continuously analyzing frame sequences and comparing against background images, the system accurately compensates for motion blur while maintaining efficient processing through iterative refinement rather than exhaustive analysis

Inventive Principle:
Principle #23Feedback

3Measurement precision

If point-spread function width is disentangled from real pointer width, then measurement precision is improved, but computational complexity increases

Engineering Contradiction:
Improvereal pointer width measurementVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a computational model that copies the point-spread function characteristics from the camera system and separates them from the actual pointer dimensions. By using mathematical modeling to represent the PSF as a distinct element, the system can disentangle it from the real pointer width measurement without requiring complex hardware or excessive computational resources

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system changes parameters by introducing separate variables for PSF width and real pointer width in the mathematical model. By parameterizing the image formation process with distinct terms for optical blur and object dimensions, the system achieves precise measurements through algorithmic separation rather than complex hardware differentiation

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9658702B2System and method of object recognition for an interactive input system
Publication Date: 2017.05.23 SMART TECH INC (CA)
  • US9658702B2 patent drawing
  • US9658702B2 patent drawing
  • US9658702B2 patent drawing

AI summary

The present invention relates to a method and system of improved pointer recognition. A camera-based interactive system has two cameras with fields of view observing an interactive surface. A processor receives a plurality of video frames from the cameras and recognizes a pointer within the video frames. Motion blur of the pointer is compensated to determine the pointer type from the compensated frames using a model-based approach.