Computer implemented methods and devices for determining dimensions and distances of head features

Patent metadata

Field	Value
Publication number	US-11798189-B2
Application number	US-202217932383-A
Country	US
Kind code	B2
Filing date	Sep 15, 2022
Priority date	Mar 16, 2020
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

Computer implemented methods and devices for determining dimensions or distances of head features are provided. The method includes identifying a plurality of features in an image of a head of a person. A real dimension of at least one target feature of the plurality of features or a real distance between at least one target feature of the plurality features and a camera device used for capturing the image is estimated based on probability distributions for real dimensions of at least one feature of the plurality of features and a pixel dimension of the at least one feature of the plurality of features.

First claim

The invention claimed is:

1. A computer implemented method for determining dimensions or distances of head features, the method comprising:
providing an image of a head of a person;
identifying a plurality of features in the image; and
estimating at least one of a real dimension of at least one target feature of the plurality of features or a real distance between at least one target feature of the plurality of features and a camera device used for capturing the image based on a probability distribution for a real dimension of at least one feature of the plurality of features and a pixel dimension of the at least one feature of the plurality of features, wherein
the estimating includes calculating a probability distribution P(pix per mm|d, θ) for a number of pixels per millimeter pix per mm for the image according to

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where d i is a number of pixels spanning an i=1, 2, . . . , Nth feature of the plurality of features, π(θ i ) represents a probability distribution of a real dimension θ i of feature i and/or its covariances with other measured pixel dimensions, and P(d i |pixel per mm, θ i ) is an operator yielding a likelihood of measuring d i based on pix per mm and θ i for a given π(θ i ).

2. The method of claim 1 , wherein the at least one feature of the plurality of features comprises at least two features of the plurality of features.

3. The method of claim 1 , wherein calculating the probability distribution for the number of pixels per millimeter for the image is based on a Monte Carlo Markov Chain type exploration of probability space.

4. The method of claim 1 , wherein the plurality of features includes one or more features selected from the group consisting of:
an interpupillary distance,
an iris diameter,
a pupil diameter,
a vertical ear length,
a Menton-Sellion distance,
a bizygomatic breadth,
an Euryon breadth,
an eye width, and
a head height.

5. The method of claim 1 , further comprising providing additional information regarding the person, and selecting probability distributions based on the additional information.

6. The method of claim 5 , wherein providing the additional information comprises receiving the additional information as a user input, and/or
determining the additional information based on the image.

7. The method of claim 5 , wherein the additional information comprises one or more of a sex of the person, an age of the person, an ethnicity of the person, or a size of the person.

8. The method of claim 1 , wherein estimating a real dimension of at least one target feature of the plurality of features comprises estimating an interpupillary distance of the person.

9. The method of claim 1 , wherein providing an image comprises providing a plurality of images, and wherein estimating is done based on the plurality of images.

10. The method of claim 1 , further comprising:
fitting a spectacle frame to the head of the person based on the estimating;
manufacturing spectacle glasses based on the estimating; or
performing an eye examination based on the estimating.

11. A computer program stored on a non-transitory data carrier and comprising instructions which, when carried out on one or more processors, cause execution of the method of claim 1 .

12. A device comprising at least one processor and the computer program of claim 11 stored for execution on the at least one processor.

13. A device, comprising:
a camera device for providing an image of a head of a person;
an analyzing unit for identifying a plurality of features in the image; and
a calculation unit for estimating at least one of a real dimension of at least one target feature of the plurality of features or a real distance between the at least one target feature of the plurality of features from the camera device used for capturing the image based on a probability distribution for a real dimension of at least one feature of the plurality of features and a pixel dimension of the at least one feature of the plurality of features, the estimating including calculating a probability distribution P(pix per mm|d, θ) for a number of pixels per millimeter pix per mm for the image according to

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Assignees

• Zeiss Carl Vision Int Gmbh

Inventors

• Hoyle Ben

Classifications

• A61B5/1072

  measuring distances on the body, e.g. measuring length, height or thickness (A61B5/1076 takes precedence) · CPC title

• A61B3/111

  for measuring interpupillary distance · CPC title

• G06V40/171 Primary

  Local features and components; Facial parts (eye characteristics G06V40/18); Occluding parts, e.g. glasses; Geometrical relationships · CPC title

• G06V40/161

  Detection; Localisation; Normalisation · CPC title

• G01B11/026

  by measuring distance between sensor and object (G01B11/0608 takes precedence) · CPC title