  We examine length measurement in curved spacetime, based on the 1+3-splitting
of a local observer frame. This situates extended objects within spacetime, in
terms of a given coordinate which serves as an external reference. The radar
metric is shown to coincide with the spatial projector, but these only give
meaningful results on the observer's 3-space, where they reduce to the metric.
Examples from Schwarzschild spacetime are given.
