Multi-camera inspection of underwater structures

• US 20060008137A1
• Filed: 09/15/2004
• Published: 01/12/2006
• Est. Priority Date: 09/19/2003
• Status: Active Grant

• Current Assignee: Miami University
• Original Assignee: Miami University
• Inventors: Firoozfam, Pezhman, Nagahdaripour, Shahriar
• Granted Patent: US 7,496,226 B2
• Time in Patent Office: Days
• US Class Current: 382/154
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• CPC Class Codes: G06V 10/16 using multiple overlapping images; Image stitching
• CPC Class Codes: G06V 20/13 Satellite images

Abstract

A method, system and apparatus for viewing and imaging an underwater structure from a submersible platform, navigating along the structure and constructing a map of the structure in the forms of a photo-mosaic and a 3-D structural map. The system can include a submersible platform, at least two cameras coupled to the submersible platform, and stereovision matching logic programmed to simulate a frontal view of a target underwater structure from a fixed distance based upon an oblique view of the target underwater structure obtained by the cameras from a variable distance. The cameras can be forward or side mounted to the submersible platform and can include optical cameras, acoustical cameras or both. Preferably, the submersible platform can be a remotely operated vehicle (ROV), or an autonomous underwater vehicle (AUV). Finally, the system further can include absolute positioning sensors.

Claims

1. A method for viewing an underwater structure comprising the steps of:

collecting a set of stereo images of the underwater structure at different positions and poses with respect to the underwater structure;

identifying stereo cues in said stereo images;

utilizing said stereo cues to match and process stereo pairs in said stereo images; and

,

rectifying said matched pairs to produce a simulated frontal view of the underwater structure.

2. The method of claim 1, wherein said identifying step comprises the step of identifying the correspondences of matching elements in said stereo images.

3. The method of claim 1, wherein said utilizing step comprises the steps of determining pose, distance, frame-to-frame movement, and a stereo disparity map.

4. The method of claim 3, wherein said determining step comprises the steps of:

first determining said pose by computing three degrees of freedom by stereo matching applied to left and right ones of stereo pairs at a specified time;

second determining said frame-to-frame movement by computing three other degrees of freedom by frame-to-frame registration at consecutive views; and

,

third determining a three dimensional shape of the underwater structure from stereo cues by stereo matching to determine disparities between corresponding points in said stereo pairs.

5. The method of claim 1, further comprising the step of generating a composite photo-mosaic and a 3-D view of the underwater structure based upon computed camera positions and one of consecutively acquired stereo images and rectified frontal views.

6. A system for viewing an underwater structure from a submersible platform comprising:

a submersible platform;

at least two cameras coupled to said submersible platform; and

,

stereovision matching logic programmed to simulate a frontal view of a target underwater structure from a fixed distance based upon an oblique view of said target underwater structure obtained by said cameras from a variable distance.

7. The system of claim 6, wherein said cameras are mounted to said submersible platform at a position selected from the group consisting of both forward mounted and both side mounted.

8. The system of claim 6, wherein said cameras are optical cameras.

9. The system of claim 6, wherein said cameras are acoustical cameras.

10. The system of claim 6, wherein said submersible platform is a remotely operated vehicle (ROV).

11. The system of claim 6, wherein said submersible platform is an autonomous underwater vehicle (AUV).

12. The system of claim 6, further comprising absolute positioning sensors.

13. A machine readable storage having stored thereon a computer program for viewing an underwater structure, the computer program comprising a routine set of instructions which when executed by a machine cause the machine to perform the steps of:

collecting a set of stereo images of the underwater structure;

identifying stereo cues in said stereo images;

utilizing said stereo cues to match stereo pairs of said stereo images; and

,

rectifying said matched pairs to produce a simulated frontal view of the underwater structure.

14. The machine readable storage of claim 13, wherein said identifying step comprises the step of identifying the correspondences of matching elements in said stereo images.

15. The machine readable storage of claim 13, wherein said utilizing step comprises the step of determining pose, distance, frame-to-frame movement and a stereo disparity map.

16. The machine readable storage of claim 15, wherein said determining step comprises the steps of:

first determining said pose by computing three degrees of freedom by stereo matching applied to left and right ones of stereo pairs at a specified time;

second determining said frame-to-frame movement by computing three other degrees of freedom by frame-to-frame registration of consecutive views; and

,

third determining a three dimensional shape of the underwater structure from stereo cues by stereo matching to determine disparities between corresponding points in said stereo pairs.

17. The machine readable storage of claim 13, further comprising a routine set of instructions for further causing the machine to perform the step of generating a composite view and a 3-D map of the underwater structure based upon computed camera positions and one of consecutively acquired stereo images and rectified frontal views.