Method and apparatus for measuring a three-dimensional curved surface shape
First Claim
1. A method of measuring a three-dimensional curved surface shape, comprising the steps of:
- causing a linear slit light to scan a surface of an object to be measured on a reference plane;
producing video signals by picking up the surface of said object using a television camera;
inputting said video signals corresponding to a plurality of picture elements into a memory means;
forming a composite image of the surface of said object by composing an image in which successive video signals of the same picture element are compared in magnitude to renew the same picture element in said memory means using as a value thereof information relating to scanning of said slit light at a time of application of the larger of said compared video signals and to thereby represent a value of each picture element in said memory means by information relating to scanning of said slit light at a time when said slit light passes respectively through a measuring point corresponding to each of said picture elements; and
measuring a three-dimensional curved surface shape of said object in accordance with said composite image.
0 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for measuring a three-dimensional curved surface shape based on a new measuring principle that a surface of an object to be measured is coded with information relating to a slit light which is used as a medium and moved or rotated at a constant speed. The manner in which a linear reflected pattern of the slit light is moved over the surface of the object to be measured is picked up by a television camera to form a composite image in which a value of each of picture elements in the image is represented by information relating to the slit light, e.g., a position, time or projection angle of the slit light at an instant that the slit light passes through one of positions on the object surface corresponding to that picture element. Then, a difference in value between each corresponding picture elements of the composite image and another composite image formed similarly with respect to a reference plane is determined to measure a three-dimensional curve surface shape of the object to be measured.
-
Citations
18 Claims
-
1. A method of measuring a three-dimensional curved surface shape, comprising the steps of:
-
causing a linear slit light to scan a surface of an object to be measured on a reference plane; producing video signals by picking up the surface of said object using a television camera; inputting said video signals corresponding to a plurality of picture elements into a memory means; forming a composite image of the surface of said object by composing an image in which successive video signals of the same picture element are compared in magnitude to renew the same picture element in said memory means using as a value thereof information relating to scanning of said slit light at a time of application of the larger of said compared video signals and to thereby represent a value of each picture element in said memory means by information relating to scanning of said slit light at a time when said slit light passes respectively through a measuring point corresponding to each of said picture elements; and measuring a three-dimensional curved surface shape of said object in accordance with said composite image. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus for measuring a three-dimensional curved surface shape comprising:
-
slit light projecting means for projecting a linear slit light onto a surface of an object to be measured on a first reference plane from a direction forming an angle θ
with said first reference plane which is not equal to 90°
;slit light scanning means for causing said linear slit light to scan the surface of said object on said first reference plane; a television camera for picking up the surface of said object from a direction different from the direction of projection of said slit light projecting means; image composing means for composing a composite image of the surface of said object by composing an image in which successive video signals of the same picture element are applied from said television camera and compared in magnitude to renew said same picture element in a memory means by using as a value thereof information relating to scanning of said slit light at a time of application of the larger of said compared video signals, whereby a value of each of said picture elements in said memory means is represented by said respective information relating to scanning of said slit light at an instant when said slit light passes through a measuring point corresponding to said respective picture element; and image processing means for measuring a three-dimensional curved surface shape in accordance with said composite image of said object. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. An apparatus for measuring a three-dimensional curved surface shape comprising:
-
slit light projecting means for projecting a linear slit light onto a surface of an object to be measured on a first reference plane from a direction forming and angle θ
with said first reference plane which is not equal to 90°
;slit light scanning means for causing said linear slit light to scan the surface of said object on said first reference plane; a television camera for picking up the surface of said object from a direction different from the direction of projection of said slit light projecting means; image composing means for composing a composite image of the surface of said object by composing an image in which video signals of the same picture element are successively applied from said television camera and successively compared in magnitude so as to renew said same picture element in a memory means by using a value thereof information relating to scanning of said slit light at a time of application of the greater one of said compared video signals, whereby a value of each of said picture elements in said memory means is represented by said respective information relating to scanning of said slit light at an instant when said slit light passes through a measuring point corresponding to said respective picture element; image processing means for measuring a three-dimensional curved surface shape in accordance with said composite image of said object; said slit light scanning means linearly scanning said slit light all over the surface of said object and said image processing means measures a three-dimensional curved surface shape of said object in accordance with the difference between the values of the picture elements of said composite image of said object and the values of the picture elements of a preliminarily determined composite image of said first reference plane; and said image processing means determines a three-dimensional shape f(x, y) of said object on the basis of a composite image u(x, y) of said object, a composite image uo (x, y) of said first reference plane and said slit light projection angle θ
with respect to said first reference plane in accordance with the equation;
space="preserve" listing-type="equation">f(x, y)=(u.sub.o (x, y)-u(x,y)) tan θwhere x and y are the positional coordinates of the picture elements.
-
Specification