Detection, 3-D positioning, and sizing of small pore defects using digital radiography and tracking
Journal article, 2014

This article presents an algorithm that handles the detection, positioning, and sizing of submillimeter-sized pores in welds using radiographic inspection and tracking. The possibility to detect, position, and size pores which have a low contrast-to-noise ratio increases the value of the nondestructive evaluation of welds by facilitating fatigue life predictions with lower uncertainty. In this article, a multiple hypothesis tracker with an extended Kalman filter is used to track an unknown number of pore indications in a sequence of radiographs as an object is rotated. Each pore is not required to be detected in all radiographs. In addition, in the tracking step, three-dimensional (3-D) positions of pore defects are calculated. To optimize, set up, and pre-evaluate the algorithm, the article explores a design of experimental approach in combination with synthetic radiographs of titanium laser welds containing pore defects. The pre-evaluation on synthetic radiographs at industrially reasonable contrast-to-noise ratios indicate less than 1% false detection rates at high detection rates and less than 0.1 mm of positioning errors for more than 90% of the pores. A comparison between experimental results of the presented algorithm and a computerized tomography reference measurement shows qualitatively good agreement in the 3-D positions of approximately 0.1-mm diameter pores in 5-mm-thick Ti-6242.


Multiple hypothesis tracker

Chain porosities

Nondestructive evaluation

Image analysis

Laser welding


Erik Lindgren

Chalmers, Materials and Manufacturing Technology, Advanced Non-destructive Testing

Eurasip Journal on Advances in Signal Processing

16876172 (ISSN) 16876180 (eISSN)

Vol. 2014 1 9- 9

Subject Categories

Other Materials Engineering

Areas of Advance

Materials Science



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