Terrestrial laser scanning has become one of the standard technologies for object acquisition in surveying engineering. The high spatial resolution of imaging and the excellent capability
of measuring the 3D space by laser scanning bear a great potential if combined for both data acquisition and data compilation. Automatic crack detection from concrete surface images is very effective for nondestructive testing. The crack information can be used to decide the appropriate
rehabilitation method to fix the cracked structures and prevent any catastrophic failure. In practice,
cracks on concrete surfaces are traced manually for diagnosis. On the other hand, automatic crack
detection is highly desirable for efficient and objective crack assessment.