Portable measurement system using image and point measurement devices

• US 5,805,289 A
• Filed: 07/07/1997
• Issued: 09/08/1998
• Est. Priority Date: 07/07/1997
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Nafis, Christopher Allen, Corby, Nelson Raymond Jr., Yamrom, Boris
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/888,795
• Time in Patent Office: 428 Days
• Field of Search: 356/375, 356/376, 356/357, 356/358, 364/506, 364/550, 364/559, 364/560, 364/552, 364/474.17, 364/474.29, 364/474.37, 382/285, 382/291, 395/119, 395/120, 395/125, 33/551
• US Class Current: 356/613
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 5/14 for measuring distance or clearance between spaced objects or spaced apertures G01B5/24 takes precedence
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures

Abstract

Calibrated spatial reference devices (SRDs) of known dimensions having targets at known relative locations are attached to a large structure to be measured. A design device employs a digital camera to acquire digital images of `islands` of the structure including the SRDs and employs photogrammetry techniques to determine relative locations of `islands` within a large structure. A highly accurate coordinate measurement device provides absolute 3D measured locations of the targets used to convert the relative photogrammetry locations into absolute 3D locations. A monitor displays the digital images, measured 3D locations, photogrammetry locations in a superimposed manner to a user and a user interface allows the user to select objects to be measured. Image detection techniques are used to identify objects selected by a user and dimensions, and distances between selected objects are automatically calculated. A remote link allows remote users to interact with the device to view, select structures and measure dimensions. The device is also capable of storing any type of imagery, notes, voice annotations, and also capable of retrieving archived information. This allows a time-lapse playback of objects indicating wear or corrosion.

Claims

1. A design device for accurately measuring dimensions of a structure with high accuracy comprising:

a) at least one spatial reference device (SRD) attached to the structure, machined to highly accurate, known dimensions, having a plurality of reference nests each which receive a target, the nests also being visible on 2D digital images;

b) a digital camera for acquiring a plurality of high resolution 2D digital images each from an associated position and orientation, `pose`, with a field of view smaller than the entire structure, and encompassing at least one SRD;

c) a coordinate measurement machine (CMM) having a base fixed with respect to the structure, for measuring an absolute `pose`, of the digital camera for each acquired 2D image, and an absolute measured location of each of the targets, with reference to the CMM base;

d) a photogrammetry unit functionally coupled to the digital camera and the CMM, for receiving the 2D digital images and their associated poses, for determining relative 3D locations of selected structures based upon the 2D images and poses;

e) an transformation device functionally coupled to the CMM and the photogrammetry device for receiving the absolute 3D measured locations and the relative 3D photogrammetry locations, and for converting the relative 3D locations into absolute 3D photogrammetry locations;

f) a monitor for modifying the 2D digital images to be correctly viewed from a user-provided viewpoint, for displaying the modified 2D images with the absolute 3D photogrammetry, and 3D measured locations superimposed upon them in correct registration to a user as viewed from the given viewpoint;

g) a user interface coupled to the monitor, which receives user-selected input to the transformation device.

2. The design device of claim 1 further comprising:

a) dimension calculation device functionally coupled to the CMM and the transformation device for calculating absolute dimensions between user-selected 3D points;

b) a user interface coupled to the dimension calculation device, and the monitor, which receives user-selected 3D points displayed on the monitor and provides these points to the dimension calculation device, then displays the received dimensions on the monitor.

3. The design device of claim 1 further comprising:

model creation device functionally coupled to the CMM, the transformation device, and the monitor which creates a 3D computer model from the 3D measured locations and the 3D photogrammetry locations, by simulating surfaces between these points, from the user-provided viewpoint.

4. The design device of claim 1 further comprising:

an archive device coupled to the user interface for selectively retrieving stored models, digital images, 3D measured and photogrammetry locations, notes, digital voice annotations and other information from the selected time period and structure region selected, and provides it to the user interface causing it to be played as a time-lapse movie on the monitor.

5. The design device of claim 1 further comprising:

a remote interface coupled to the user interface and a site of remote users at a remote location, for providing remote user input to the user interface.

6. The design device of claim 1 further comprising:

a laser ranging device, functionally coupled to the model creation device, for scanning the surface of an object to determine distances from the laser ranging device at a plurality of points on its surface, providing relative 3D locations to the model creation device; and

wherein the CMM is aimed to track a pose of the laser ranging device and provides the pose to the transformation device to determine absolute locations from the 3D relative locations.

7. The design device of claim 6 further comprising:

a filter coupled to the laser ranging device to filter out points which change abruptly from adjacent points to smooth the data, and then provides this filtered data to the model creation device in place of the unfiltered data.

8. The design device of claim 1 wherein the photogrammetry unit comprises:

a) an image identification unit which identifies on the digital images, the targets, and their center points, the boundaries of an object within the images selected by a user, and a point to be used for measurement within the object;

b) a photo measurement device which determines the scale of each of the images and then determines dimensions between measurement points of the objects.