Abstract: Panoramic annular lens is a special optical imaging device, which is used in morphology
detection of pipeline. It is capable of ignoring hollow image in the radial direction and getting
panoramic picture of whole pipeline inside wall. This has absorbed advantages of tangential
expansion of traditional unwrapping algorithm, designing a calibration experiment, using edge
extraction, Hough transform, and interpolation principle to improve radial development, and obtaining
adaptive expansion algorithm to different pipe diameter. Simulation experiment showed that this
method is effective to improve radial magnification, and applies to pipes with different diameters.

Key words: panoramic image, radial expansion, adaptive, simulation