Apparatus and method for three-dimensional perspective imaging of objects

A method of imaging an object surface, the steps of the method comprising:

• training a projected light ray upon an object surface to produce an illuminated point on the object surface;
• providing a video camera having an optical axis, a focal length, a vanishing point and a sensor matrix, the optical axis being parallel to the projected light ray, the sensor matrix defining a sensor matrix plane perpendicular to the projected light ray, the vanishing point being at the focal length distance from the sensor matrix plane along the optical axis toward the object;
• determining a source point corresponding to the intersection of the sensor matrix plane and the line defined by the projected light ray, wherein the vanishing point and the source point define a vanishing point line;
• viewing the object surface with the video camera to determine a sensed point lying in the sensor matrix plane and corresponding to the illuminated point on the object surface;
• defining a normal line perpendicular to the sensor matrix plane and passing through the sensed point lying in the sensor matrix plane;
• determining an image point corresponding to the intersection of the normal line with the vanishing point line;
• computing three-dimensional image coordinates corresponding to the image point;
• and
• transforming the three-dimensional image coordinates into three-dimensional object coordinates representing the illuminated point on the object surface.

A method of creating a three-dimensional image of an object surface, the steps of the method comprising:

• projecting a plane of light upon an object surface to produce a stripe comprising a plurality of illuminated points on the object surface;
• providing a video camera having an optical axis, a focal length, a vanishing point and a sensor matrix, the optical axis being parallel to the plane of light, the vanishing point being a focal length distance from the sensor matrix along the optical axis toward the object, the sensor matrix defining a sensor matrix plane substantially perpendicular to the plane of light;
• determining a plurality of source points, each one of the source points lying on the line defined by the intersection of the sensor matrix plane with the plane defined by the projected plane of light, wherein the vanishing point and each one of the source points define a corresponding vanishing point line;
• viewing the object surface with the video camera to obtain an image stripe comprising a plurality of sensed points lying in the sensor matrix plane, each one of the sensed points corresponding to one of the illuminated points on the object surface;
• defining a normal line corresponding to each one of the sensed points, each normal line being perpendicular to the sensor matrix plane and passing through the corresponding one of the sensed points;
• determining a plurality of image points, each one of the image points corresponding to the intersection of the vanishing point line for the corresponding one of the source points and the normal line for the corresponding one of the sensed points;
• computing three-dimensional image coordinates for each one of the image points;
• and
• transforming the three-dimensional image coordinates into three-dimensional object coordinates representing the object surface.

An apparatus for creating a three-dimensional image of an object surface, the apparatus comprising:

• a light source adapted to train a plane of light upon an object surface to produce a stripe consisting of a plurality of illuminated points on the object surface;
• a video camera having an optical axis, a focal length and a vanishing point, the optical axis of the video camera being substantially parallel to the projected plane of light, the video camera also having a sensor matrix defining a sensor matrix plane which is substantially perpendicular to the optical axis of the video camera, the vanishing point of the video camera being substantially at the focal length distance from the sensor matrix plane along the optical axis of the video camera toward the object;
• means for determining a plurality of source points lying on the line defined by the intersection of the sensor matrix plane with the plane defined by the projected plane of light, wherein the vanishing point and each one of the source points define a corresponding vanishing point line;
• means for determining a plurality of sensed points lying in the sensor matrix plane, each one of the sensed points corresponding to one of the illuminated points on the object surface;
• processing means for determining a plurality of normal lines perpendicular to the sensor matrix plane wherein each one of the normal lines passes through a corresponding one of the sensed points, and for computing three-dimensional image coordinates for a plurality of image points wherein each one of the image points is defined by the intersection of a corresponding one of the normal lines with the vanishing point line;
• and
• transformation means for converting the three-dimensional image coordinates into three-dimensional object coordinates representing the object surface.