Spatial Parameter Determination Using Pixel Coordinates and Focal Length

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Solution Overview

Problem

Existing methods for determining the real size of an object in an image require a reference object, which is inconvenient when objects are photographed at different distances, leading to varying pixel occupancy on the camera's image sensor, making it difficult to accurately assess the object's size.

Innovation Solution

A method and apparatus that determine a spatial parameter by calculating the image distance between pixel coordinates and the object distance using the focal length of the camera lens, allowing for the real size of the object to be quantified without a reference object, by determining pixel coordinates, image distance, and object distance, and using these parameters to calculate the spatial parameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a reference object is placed in the scene to illustrate the size of an object, then the viewer may have an intuitive cognition of the size of the object, but objects photographed at different distances occupy different numbers of pixel points on the image sensor, making it unable to conveniently learn about the real size of the photographed object

Engineering Contradiction:
Improveconvenience of determining real sizeVSAvoidaccuracy of real size determination
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the parameters used for size determination from simple pixel counting to a mathematical model involving pixel coordinates, image distance, object distance, and focal length. By transforming the measurement parameters and their relationships, the system can calculate real size accurately regardless of shooting distance, resolving the contradiction between operational convenience and measurement precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical approach of physically placing reference objects in the scene with a computational approach using camera parameters and coordinate mathematics. This substitution eliminates the need for physical reference objects while maintaining or improving measurement accuracy through calculated relationships between pixel coordinates and real-world dimensions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the size of an object is illustrated by means of a reference object in the image, then the viewer may have an intuitive cognition of the size, but it requires placing additional objects in the scene which increases device complexity

Engineering Contradiction:
Improveease of size illustrationVSAvoidcomplexity of requiring reference object
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts and utilizes the camera's inherent parameters (focal length, sensor characteristics) and the image's coordinate information to determine real size. By taking out and leveraging these existing resources rather than adding reference objects, the system achieves size illustration functionality without increasing device complexity or requiring additional physical components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent enables the camera system to determine real size using its own inherent parameters and the image data it captures. The camera's focal length, sensor pixel dimensions, and the image's coordinate system serve the dual purpose of capturing the image and providing the basis for size calculation, eliminating the need for external reference objects and simplifying the overall system.

Inventive Principle:
Principle #25Self-service

3Device complexity

If pixel coordinates are used to represent object size in an image, then the representation is simple, but without considering image distance and object distance, the real size cannot be accurately determined

Engineering Contradiction:
Improvesimplicity of pixel coordinate systemVSAvoidaccuracy of real size calculation
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent transitions from two-dimensional pixel coordinates to three-dimensional spatial relationships by incorporating image distance and object distance as additional dimensions. This dimensional expansion allows the system to maintain the simplicity of coordinate-based representation while accurately calculating real size by considering the depth information provided by distance parameters and focal length.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3121557B1Method and apparatus for determining spatial parameter based on an image
Publication Date: 2021.08.25 XIAOMI INC
  • EP3121557B1 patent drawingFigure 1A~1B
  • EP3121557B1 patent drawingFigure 1C~2
  • EP3121557B1 patent drawingFigure 3~4

AI summary

A method for determining a spatial parameter based on an image includes: determining (S 101, S201, S301) a first pixel coordinate corresponding to an image and a second pixel coordinate corresponding to the image displayed on a display device; determining (S102) an image distance between the first pixel coordinate and the second pixel coordinate; and determining (S103, S206, S304) a spatial parameter between the first pixel coordinate and the second pixel coordinate according to the image distance, an object distance for photographing the image and a focal length of a lens in a camera apparatus for photographing the image. According to the technical solution of the present disclosure, the real size of the photographed object can be quantized based on the image, without having to illustrating the real size of the photographed object in contrast with a reference object placed in the image, thereby improving the user experience.