Method and apparatus of image mensuration with selectively visible and invisible reseau grid marks

• US 5,040,059 A
• Filed: 02/27/1989
• Issued: 08/13/1991
• Est. Priority Date: 08/03/1987
• Status: Expired due to Fees

• Current Assignee: Vexcel Imaging Corporation
• Original Assignee: Vexcel Corporation (Microsoft Corporation)
• Inventors: Leberl, Franz W.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US07/316,327
• Time in Patent Office: 897 Days
• Field of Search: 358/109, 358/107, 358/93, 358/225, 358/903, 350/320, 356/401, 364/560
• US Class Current: 348/135
• CPC Class Codes: G01C 11/04 Interpretation of pictures
• CPC Class Codes: G06K 11/00 Methods or arrangements for graph-reading or for converting the pattern of mechanical parameters, e.g. force or presence, into electrical signal feelers for copying devices on machine tools B23Q35/00; arrangements for measuring areas G01B; measuring force G01L; adapted as input devices to computers G06F3/00; combined with pattern recognition G06F18/00; arrangements for image or video recognition or understanding G06V10/00; character recognition, recognising digital ink or document-oriented image-based pattern recognition G06V30/00; systems for transmitting the position of an object with respect to a predetermined reference system, e.g. tele-autographic system, G08C21/00
• CPC Class Codes: H04N 1/195 the array comprising a two-dimensional array or a combination of two-dimensional arrays
• CPC Class Codes: H04N 1/19594 using a television camera or a still video camera
• CPC Class Codes: H04N 1/3873 defined only by a limited number of coordinate points or parameters, e.g. corners, centre; for trimming
• CPC Class Codes: H04N 2201/0426 Scanning an image in a series of contiguous zones

Abstract

The method of this invention includes the steps of positioning a reseau with grid marks on the object and sequentially illuminating the grid marks separate from the object and illuminating the object separate from the grid marks or in a manner that the grid marks are not visible with the object. The image of the grid mark positions, when illuminated, are digitized and stored in computer memory and correlated with the image of the object when it is illuminated and digitized. The scale of the image can also be correlated to the scale of the grid marks.

Claims

1. A method of image mensuration, comprising the steps of:

positioning a reseau with precisely spaced grid marks thereon on an exposed surface of an object containing an image and at a spaced distance from an array of optical sensors that is capable of converting illuminated images to digital data, said array of optical sensors having gain control capabilities;

illuminating the object image;

while simultaneously illuminating the reseau grid marks with greater luminous intensity than the luminous intensity with which said object image is illuminated;

adjusting the gain control of the array of optical sensors so that the greater luminous intensity of the reseau grid marks become visibly distinct of the reseau grid marks become visibly distinct to the array of optical sensors;

digitizing and storing the image of the grid marks within the view of said array of optical sensors;

removing the grid marks from the capability of the array of optical sensors to view them;

adjusting the gain control of the array of optical sensors so that the object image becomes visibly distinct to the array of optical sensors;

digitizing and storing the object image within the view of said array of optical sensors;

correlating the digital data of the spatial positions of the grid mark images in relation to the digital data of the object images; and

mensurating the displayed image in a scale calibrated with respect to the digitized reseau grid marks image.

2. The method of claim 1, including the step of providing the reseau in the form of a transparent plate with grid marks in the form of grooves formed in the transparent plate with surfaces that reflect and diffract light rays traveling longitudinally through said transport plate into the array of optical sensors, and illuminating said grid marks by positioning a side light adjacent a peripheral edge of the transparent plate for directing light rays longitudinally through said transparent plate.

3. The method of claim 2, including the steps of illuminating said grid marks with a Xenon light and removing the grid marks from the capability of the array of optical sensors to view them by eliminating the Xenon illumination.

4. Reseau grid apparatus for providing grid marks for an image on an object to be digitized by an array of optical sensors, comprising:

an object mounting plate for supporting the object;

reseau means for holding the object on the mounting plate and for providing reseau grid marks correlated geometrically with the image, said reseau means including a thin transparent reseau plate adapted for positioning on the object mounting plate and having two opposite planar surfaces with edges around its perimeter, and a plurality of grid marks in the form of grooves etched on one of the surfaces of the reseau plate;

object illumination means adjacent said object mounting plate for illuminating the image on the object positioned on the object mounting plate; and

grid illumination means positioned adjacent an edge of the reseau plate for illuminating the grid marks by directing light longitudinally through said reseau plate from the edge of the reseau plate to the grooves in the surface of the reseau plate, said grid illumination means being capable of providing a greater luminous intensity than the object illumination means such that the grid marks when illuminated are not washed out by the object illumination means.

5. A reseau grid apparatus for providing grid marks for an image on an object to be digitized by optical sensor apparatus, comprising:

an object plate for supporting the object adjacent said optical sensor apparatus;

a transparent reseau plate adapted for positioning on the object, said reseau plate including a plurality of precisely spaced and precisely positioned reseau grid marks comprising an optically active material that can be activated to change its transparency to light;

object illumination means positioned adjacent said object plate for illuminating the object; and

grid mark activation means connected to said reseau plate for activating said optically active material to change its transparency.

6. The apparatus of claim 5, wherein optically active material is an electrochromic film and the grid mark activation means includes a means of supplying an electric potential across the electrochromic film.

7. A reseau grid apparatus for providing grid marks for an image of an object to be digitized by a system that includes an array of optical sensors and is capable of converting an optical image to digital data, comprising:

an object mounting plate for supporting the object a spaced distance away from said array of optical sensors;

a transparent reseau plate adapted for positioning on an object that is placed on the object mounting plate and having two opposite generally planar surfaces with edges around its perimeter, said reseau plate also including a plurality of precisely spaced and precisely positioned grid marks that are capable of causing light of a unique character to emerge from one of said planar surfaces of said reseau;

object illumination means adjacent said object mounting plate for illuminating the object positioned on the object mounting plate to create an optical image of the object; and

optical filter means removeably positionable between said reseau plate and said array of optical sensors for selectively transmitting and blocking said light of a unique character that emerges from said reseau.

8. The apparatus of claim 7, wherein said grid marks are in the form of grooves formed in the surface of the reseau plate that is positioned adjacent the object, said grooves being formed with surfaces that reflect and diffract light rays traveling longitudinally through said transparent reseau plate to emerge from the surface of the transparent reseau plate that is opposite the grid mark grooves and into the array of optical sensors, and said apparatus also including grid mark illumination means positioned adjacent an edge of the reseau plate for illuminating the grid marks by directing light of said unique character longitudinally through said reseau plate from the edge of the reseau plate to the grooves in the surface of the reseau plate.

9. The apparatus of claim 7, wherein said grid marks include a material that transmits only said light of a unique character.

10. A method of image processing, comprising the steps of:

positioning as reseau with precisely spaced grid marks thereon adjacent and parallel, yet at a slight distance from, an exposed surface of an object containing an image and at a substantially greater distance from a solid state camera containing an optical sensor that is capable of converting illuminated images to digital data and having a focus adjusting system for adjustably focusing an optical image on the optical sensor;

adjusting the focus adjusting system of the solid state camera such that an optical image of the grid marks is in focus on the optical sensor and an optical image of the object is sufficiently blurred on the optical sensor to be washed out, converting the optical image of the grid marks to digital data, and storing the digital data, including spatial location of the grid marks, in a computer memory;

adjusting the focus adjusting system such that the image of the grid marks become sufficiently blurred to be washed out and the image of the object comes into focus on the optical sensor, converting the image of the object to digital data, and storing the digital data of the object in a computer memory;

computing the parallax error created by the slight distance of the grid marks from the image;

correlating the digital data of the spatial positions of the grid mark images in relation to the digital data of the object images by reference to the camera position in relation to both the grid marks image and the object image, making adjustment for the computated parallax error; and

processing the digital data of the image of the object in a scale calibrated by the computer with respect to the digital data of the reseau grid marks image.

11. Reseau grid apparatus for providing grid marks for an image on an object to be digitized by a solid state camera system that includes optical sensors comprising:

an object mounting plate for supporting the object a substantial spaced distance from the solid state camera and optical sensors;

reseau means adapted for positioning closely adjacent the object with only a slight distance between the reseau means and the object for providing a reseau grid marks image to be correlated geometrically with the object image, said reseau means including transparent reseau plate adapted for positioning parallel to but separated from the object mounting plate; and

focus adjusting means associated with said solid state camera system for alternately focusing the grid marks image on the optical sensor while defocusing the object image and then focusing the object image on the optical sensors while defocusing the grid marks image.

12. A method of processing an optical image of an object, comprising the steps of:

placing on said object a transparent reseau plate with precisely spaced grid marks thereon comprising light polarizing materials that differentially transmit light polarized in one plane through the grid marks;

positioning said object and reseau plate adjacent optical sensing apparatus that is capable of converting optical images to digital data;

illuminating said reseau plate with light polarized in a plane different than said one plane that is not transmitted by said grid marks such that said grid marks appear as dark grid mark images;

exposing said optical sensing apparatus with said grid mark images and converting said dark grid mark images to digital data;

illuminating said object and reseau plate with light that is transmitted through all of said reseau plate including said grid marks to illuminate said optical image on said object;

exposing said optical sensing apparatus with said optical image on said object, and converting the optical image on the object to digital data;

correlating the digital data of the grid mark images with the digital data of the object image; and

processing the object image in conjunction with scales and positions defined by said grid marks.

13. A method of processing and optical image of an object, comprising the steps of:

placing on said object a reseau plate comprising light polarizing material that transmits light that is polarized in one plate interspersed with material defining precisely spaced grid marks that also pass light that is not polarized in said one plane;

positioning said object and reseau plate adjacent an optical sensing apparatus that is capable of converting optical images to digital data;

illuminating said reseau plate with light polarized in said one plate such that it is transmitted only by said grid marks and thereby creating an illuminated optical image of said grid marks in a darkened field;

exposing said optical sensing apparatus with said optical grid mark images, and converting said optical grid mark images to digital data;

illuminating said object and reseau plate with light that is transmitted through all of said reseau plate including said grid marks to illuminate said optical image on said object;

exposing said optical sensing apparatus with said optical image on said object, and converting the optical image on the object to digital data;

correlating the digital data of the grid mark images with the digital data of the object image; and

processing the object image in conjunction with scales and positions defined by said grid marks.

14. A method of processing an object image on an object, comprising the steps of:

placing on said object a transparent reseau plate that includes a plurality of precisely spaced and precisely positioned grid mark comprising material that is capable of altering its light transmissive properties in response to a change in electric potential across the material;

positioning said object and reseau plate adjacent an optical sensing apparatus that is capable of converting optical images to digital data;

illuminating said reseau plate and setting an electric potential across said material comprising said grid marks in such a manner as to set the light transmissive properties of said grid marks to produce an optical image of said grid marks;

exposing said optical sensing apparatus with said optical grid mark images, and converting said optical grid mark images to digital data;

changing the electric potential across said material comprising said grid marks in such a manner as to change the light transmissive properties of said material in such a manner as to transmit light comprising in such a manner as to transmit light comprising an optical image of said object without distortion and interference by said grid marks;

exposing said optical sensing apparatus with said optical image of said object, and converting the optical imager of the object to digital data;

correlating the digital data of the grid marks images with the digital data of the object image; and

processing the object image in conjunction with scales and positions defined by said grid marks.

15. The method of claim 14, including the step of providing said grid mark material as an optically active, electrochromic material that increases and decreases in transparency in response to changes of electric potential across said material.

16. A method of processing an optical image of an object, comprising the steps of:

placing on said object a transparent reseau plate with precisely spaced and precisely positioned grid marks that cause light of a unique character to emerge from said grid marks such that said light of a unique character comprises an optical image of said grid marks;

positioning said object and reseau plate adjacent an optical sensing apparatus that is capable of converting optical images to digital data;

illuminating said grid marks in such a manner as to cause said light of a unique character to emerge from said reseau plate;

exposing said optical sensing apparatus with said optical grid marks images, and converting said optical grid mark images to digital data;

positioning a filter between said reseau plate and said optical sensing apparatus that has a characteristic of blocking said light of a unique character and transmitting light of a different character to block said grid marks image from said optical sensing apparatus;

illuminating the object and reseau plate with light of a different characteristic to create an optical image of said object;

exposing said optical sensing apparatus with said optical image of said object, and converting the optical image of the object to digital data;

correlating the digital data of the grid marks image with the digital data of the object image; and

processing the object image in conjunction with scales and positions defined by said grid marks.

17. The method of claim 16, including the step of making said light of a unique character light having a limited wavelength.

18. The method of claim 16, including the step of making the light of a unique character in light polarized in one plane.