Systematic Pointing Errors with Retro-Reflective Targets
Accurate target detection is fundamental to many industrial measuring applications. One type of target uses retroreflective material for defining object surface points. In a photogrammetric procedure cameras at different positions illuminate these targets which are imaged on to the charge coupled device (CCD) array. By intersecting all the lines of sight, the targets are fixed in space. In the past, accuracy improvements concentrated mainly on algorithms or sensor calibration, such as better modelling of optical and electronic distortions. Less effort was spent on potential targeting problems. It is conventionally assumed that the target centre is physically fixed and independent of the angle alpha between the target normal and the line of sight. The discussion investigated this assumption in the case of retroreflective targets. Tests have revealed a systematic shift of the target center from -30 um to +30 um normal to the line of sight, when the target is viewed from different directions. There is no shift seen for punched retroreflective targets.
Bibliographic Reference: Article: IAPRS, Vol. 30 (1995)
Record Number: 199610055 / Last updated on: 1996-02-16
Original language: en
Available languages: en