# US 2014/0152956 A1 · System for the measurement of the interpupillary distance using a device equipped with a display and a camera > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152956 A1 - Document ID: US20140152956A1 - Status: Published application - Kind: A1 - Application number: 14/089,552 - Filed: 2013-11-25 - Published: 2014-06-05 - Earliest claimed: 2012-07-03 - Assignees: Reverse Engineering, Lda - Applicants: Reverse Engineering, Lda - Inventors: Cesar Augusto dos Santos SILVA; Andre Filipe Marques da SILVA - Web page: https://patentgrep.com/patent/US20140152956A1 ## CPC - G02C 13/003: {Measuring during assembly or fitting of spectacles} - A61B 3/0025: {characterised by electronic signal processing, e.g. eye models} - A61B 3/111: {for measuring interpupillary distance} - G02C 13/005: {Measuring geometric parameters required to locate ophtalmic lenses in spectacles frames (apparatus for testing or instruments for examining the eyes per se A61B3/00; machines or devices and accessories for grinding the edges of lenses using spectacles as a template B24B9/144)} - G02C: SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES (trial frames for testing the eyes A61B3/04; goggles or eyeshields not having the same features as spectacles A61F9/00) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A system for measuring the interpupillary distance of two eyes of a face using a device equipped with a display and a camera. For example, a guide marker (or guide markers) is displayed on a reflective display, and an image is captured using the camera when the reflection of the face is aligned with the guide marker. A stereo pair is created using the camera image and the reflection of the face on the display, and the interpupillary distance is determined by comparing the three-dimensional positions of the two eyes. The device is capable of calibration using a calibration object to detect the distance between the guide marker on the display and the camera. A facial recognition engine is employed in some cases to detect the eyes or other points on the camera image. ## Claims ### Claim 1 A method of determining a distance on a human body using an electronic device, the method comprising: displaying at least one guide marker on a display, the display having a reflective surface; capturing an image via a camera associated with the display, the image including two points on a body, wherein when the image is captured a reflection of the two points is aligned with the at least one guide marker; determining a three-dimensional position of each point based on a stereo pair, the stereo pair including the image and the reflection of the two points aligned with the at least one guide marker; and calculating the distance between the two points by comparing the three-dimensional positions of each point. ### Claim 2 (depends on 1) The method of claim 1, wherein the two points on the body are the centers of each of two pupils of a pair of eyes of a face. ### Claim 3 (depends on 1) The method of claim 1, wherein the distance between the two points is the interpupillary distance. ### Claim 4 (depends on 3) The method of claim 3, wherein the capturing step is repeated to capture a plurality of images, wherein each of the plurality of images correspond with different interpupillary distances. ### Claim 5 (depends on 1) The method of claim 1, further comprising determining calibration information of the camera. ### Claim 6 (depends on 5) The method of claim 5, wherein determining the calibration information of the camera includes: capturing an image via the camera, the image including a calibration object having a known geometric relationship to the camera and the display; detecting a calibration point on the calibration object in the image; and comparing the calibration point of the image to predefined calibration point data to determine the spatial distance between the at least one guide marker and the camera and the field of view of the camera. ### Claim 7 (depends on 6) The method of claim 6, wherein the calibration object includes a pattern of calibration points, the calibration point being detected by detecting at least a portion of the pattern of calibration points. ### Claim 8 (depends on 1) The method of claim 1, further comprising detecting the two points in the image. ### Claim 9 (depends on 8) The method of claim 8, wherein detecting the two points engages a facial recognition engine. ### Claim 10 (depends on 1) The method of claim 1, wherein the three-dimensional position of each point is given by an intersection of a projection ray and a plane extending normal to the reflective surface through at least a portion of the at least one guide marker, each projection ray passing through one of the points and the camera, the points being coincident with the plane. ### Claim 11 (depends on 10) The method of claim 10, wherein the at least one guide marker comprises a line on the display and the line is coincident with the plane defined by the at least one guide marker. ### Claim 12 A computing device configured to determine a distance on a human body, the device comprising: a processor; memory in electronic communication with the processor; computer readable instructions stored by the memory that cause the processing circuit to perform a method comprising: displaying at least one guide marker on a display, the display having a reflective surface; capturing an image via a camera associated with the display, the image including two points on a body, wherein when the image is captured a reflection of the two points is aligned with the at least one guide marker; determining a three-dimensional position of each point based on a stereo pair, the stereo pair including the image and the reflection of the two points aligned with the at least one guide marker; and calculating the distance between the two points by comparing the three-dimensional positions of each point. ### Claim 13 (depends on 12) The computing device of claim 12, wherein the two points on the body are the centers of each of two pupils of a pair of eyes of a face, and the distance between the two points is the interpupillary distance. ### Claim 14 (depends on 13) The computing device of claim 13, wherein the capturing step is repeated to capture a plurality of images, wherein each of the plurality of images corresponds with different interpupillary distances. ### Claim 15 (depends on 12) The computing device of claim 12, further comprising determining calibration data of the camera. ### Claim 16 (depends on 15) The computing device of claim 15, wherein determining the calibration data includes: capturing an image via the camera, the image including a calibration object having a known geometric relationship to the camera and the display; detecting a calibration point on the calibration object in the image; and determining the spatial distance between the at least one guide marker and the camera and a field of view of the camera by comparing the calibration point of the image to predefined calibration point data. ### Claim 17 (depends on 16) The computing device of claim 16, wherein the calibration object includes a calibration pattern, the calibration point being detected by detection of the calibration pattern. ### Claim 18 (depends on 12) The computing device of claim 12, further comprising detecting the two points in the image. ### Claim 19 (depends on 18) The computing device of claim 18, wherein detecting the two points engages a facial recognition engine. ### Claim 20 (depends on 12) The computing device of claim 12, wherein the three-dimensional position of each point is given by an intersection of a projection ray and a plane extending normal to the reflective surface through at least a portion of the at least one guide marker, the projection ray passing through the point and the camera, the points coincident with the plane. ### Claim 21 (depends on 20) The computing device of claim 20, wherein the at least one guide marker comprises a line on the display and the line is coincident with the plane defined by the at least one guide marker. ### Claim 22 A computer program product for determining, by a processor, a distance on a human body, the computer program product comprising a non-transitory computer-readable medium storing instructions thereon, the instructions being executable by the processor to: display at least one guide marker on a display, the display having a reflective surface; capture an image via a camera associated with the display, the image including two points on a body, wherein when the image is captured a reflection of the two points is aligned with the at least one guide marker; determine a three-dimensional position of each point based on a stereo pair, the stereo pair including the image and the reflection of the two points aligned with the at least one guide marker; and calculate the distance between the two points by comparing the three-dimensional positions of each point.