Visual mapping for natural gas pipe inspection. (April 2015)

• Record Type: Journal Article
• Authors: Hansen, Peter; Alismail, Hatem; Rander, Peter; Browning, Brett
• Is Part Of: International journal of robotics research. Volume 34:Number 4/5(2015)
• Page Start: 532
• Page End: 558
• Publication Date: 2015-04
• Subjects: Visual mapping -- visual odometry -- pipe inspection -- natural gas -- field robotics -- fisheye camera; Robots -- Periodicals; Robots, Industrial -- Periodicals; 629.89205
• DOI: 10.1177/0278364914550133
• Languages: English
• ISSNs: 0278-3649

Abstract

Validating the integrity of pipes is an important task for safe natural gas production and many other operations (e.g. refineries, sewers, etc.). Indeed, there is a growing industry of actuated, actively driven mobile robots that are used to inspect pipes. Many rely on a remote operator to inspect data from a fisheye camera to perform manual inspection and provide no localization or mapping capability. In this work, we introduce a visual odometry-based system using calibrated fisheye imagery and sparse structured lighting to produce high-resolution 3D textured surface models of the inner pipe wall. Our work extends state-of-the-art visual odometry and mapping for fisheye systems to incorporate weak geometric constraints based on prior knowledge of the pipe components into a sparse bundle adjustment framework. These constraints prove essential for obtaining high-accuracy solutions given the limited spatial resolution of the fisheye system and challenging raw imagery. We show that sub-millimeter resolution modeling is viable even in pipes which are 400 mm (16") in diameter, and that sparse range measurements from a structured lighting solution can be used to avoid the inevitable monocular scale drift. Our results show that practical, high-accuracy pipe mapping from a single fisheye camera is within reach.