Method and system for calibrating a wearable heads-up display to produce aligned virtual images in an eye space

Patent metadata

Field	Value
Publication number	US-2021325669-A1
Application number	US-202117356268-A
Country	US
Kind code	A1
Filing date	Jun 23, 2021
Priority date	Aug 31, 2018
Publication date	Oct 21, 2021
Grant date	—

Abstract

A wearable heads-up display has stored therein two or more distortion models for use in generating distorted source images that when projected by the wearable heads-up display into a target eye space form virtual images are aligned in the target eye space. A method and system for determining the distortion models are disclosed.

First claim

1 - 22 . (canceled)

23 . A method, comprising:
projecting one or more test patterns by a projector of a wearable heads-up display; capturing, by a camera, an image of each of the one or more projected test patterns; based at least in part on the captured images, determining a first mapping that maps points in a projector space to points in a camera space; acquiring a second mapping that maps points in the camera space to points in the target eye space; and based on the first mapping and the second mapping, storing, as a distortion model for use in distorting a source image, a third mapping that maps points in the target eye space to points in the projector space.

24 . The method of claim 23 , wherein determining the first mapping comprises decoding the captured images to find correspondence between projector frame buffer pixels and camera pixels.

25 . The method of claim 24 , wherein decoding the captured images comprises detecting Gray codes in the captured images.

26 . The method of claim 23 , further comprising:
determining the third mapping, the determining of the third mapping including identifying at least one region of interest in the target eye space and determining the third mapping for the at least one region of interest in the target eye space.

27 . The method of claim 23 , further comprising determining the third mapping at a first temperature to obtain a first distortion model at the first temperature and determining the third mapping at a second temperature to obtain a second distortion model at the second temperature.

28 . The method of claim 23 , wherein projecting the one or more test patterns comprises:
for each position in a select sequence, generating copies of a first test pattern of the one or more test patterns at the position and projecting the copies of the first test pattern, each of the copies corresponding to a unique combination of exit pupil and color channel of the wearable heads-up display.

29 . The method of claim 28 , wherein capturing an image of each of the one or more test patterns comprises capturing an image having image portions corresponding to the copies of the first test pattern.

30 . The method of claim 29 , wherein determining the first mapping comprises determining the first mapping for each unique combination of color channel and exit pupil.

31 . The method of claim 23 , further comprising generating the one or more test patterns prior to storing the third mapping, wherein generating the one or more test patterns comprises generating at least one test pattern carrying codes.

32 . The method of claim 31 , wherein generating at least one test pattern comprises generating the at least one test pattern with a Gray code.

33 . The method of claim 31 , wherein determining the first mapping comprises decoding the at least one test pattern.

34 . The method of claim 31 , wherein generating the one or more test patterns further comprises generating at least one additional test pattern having features with known positions in a frame buffer of the projector.

35 . The method of claim 34 , wherein determining the first mapping comprises decoding the at least one test pattern and the at least one additional test pattern.

36 . The method of claim 23 , wherein projecting the one or more test patterns comprises transmitting the one or more test patterns to a processor of the wearable heads-up display for rendering the one or more test patterns into a frame buffer of the projector.

37 . The method of claim 23 , wherein storing the third mapping comprises storing the third mapping in a non-transitory processor-readable storage medium of the wearable heads-up display.

38 . The method of claim 23 , wherein capturing an image of each of the one or more projected test patterns comprises positioning the camera relative to the wearable heads-up display to capture at least a portion of images projected by the projector of the wearable heads-up display.

39 . A calibration system, comprising:
a camera; a calibration processor communicatively coupleable to a wearable heads-up display (WHUD) and communicatively coupled to the camera; and a non-transitory processor-readable storage medium communicatively coupled to the calibration processor and storing executable instructions that, when executed, cause the calibration processor to:
capture, via the camera, an image of each of one or more test patterns projected by a projector of the WHUD;
based at least in part on the captured one or more images, determine a first mapping that maps points in a projector space to points in a camera space;
acquire a second mapping that maps points in the camera space to points in a target eye space; and
store, as a distortion model for use in distorting a source image and based on the first mapping and the second mapping, a third mapping that maps points in the target eye space to points in the projector space.

40 . The calibration system of claim 39 , wherein the calibration processor is communicatively coupleable to a processor of the WHUD.

41 . The calibration system of claim 39 , further comprising the WHUD, and wherein the projector is to project the one or more test patterns in a select sequence of positions by:
for each position in the select sequence, generating copies of a first test pattern of the one or more test patterns at the position and projecting the copies of the first test pattern by the projector, wherein each of the copies corresponds to a unique combination of exit pupil and color channel.

42 . The calibration system of claim 41 , wherein the executable instructions that cause the calibration processor to capture an image of each of the one or more test patterns include instructions that cause the calibration processor to capture an image having image portions corresponding to the copies of the first test pattern.

43 . The calibration system of claim 42 , wherein the instructions that cause the calibration processor to determine the first mapping include instructions that cause the calibration processor to determine the first mapping for each unique combination of exit pupil and color channel.

44 . The calibration system of claim 39 , wherein the executable instructions further cause the calibration processor to generate the one or more test patterns prior to storing the third mapping, wherein to generate the one or more test patterns includes to generate at least one test pattern carrying codes and at least one additional test pattern having features with known positions in a frame buffer of the projector.

Assignees

• Google Llc

Inventors

• Urquhart Daniel Thomson
• Balzerson Daniel
• Kintel Marius

Classifications

• G02B2027/0138

  comprising image capture systems, e.g. camera · CPC title

• G02B2027/011

  comprising device for correcting geometrical aberrations, distortion · CPC title

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• H04N9/3197

  using light modulating optical valves · CPC title

• H04N9/3147

  Multi-projection systems (video walls G06F3/1446) · CPC title