ShapeArray (SAA) is able to determine its shape by measuring the static tilts due to gravity in each of its segments. The software that Measurand uses is based on the assumption that the acceleration is due to gravity alone and is unchanging (i.e. static). Some people have the misconception that ShapeArray actually double-integrates accelerations to determine position, but this is not the case! There would be a number of difficulties involved with trying to do this, chief among them that even very small errors in measured acceleration tend to become large position errors if you double-integrate for too long. So if the ShapeArray is shaking back and forth or even swaying gently, you won’t be able to accurately resolve that motion.