  We report experimental measurements of the translational and rotational
dynamics of a large buoyant sphere in isotropic turbulence. We introduce an
efficient method to simultaneously determine the position and (absolute)
orientation of a spherical body from visual observation. The method employs a
minimization algorithm to obtain the orientation from the 2D projection of a
specific pattern drawn onto the surface of the sphere. This has the advantages
that it does not require a database of reference images, is easily scalable
using parallel processing, and enables accurate absolute orientation reference.
Analysis of the sphere's translational dynamics reveals clear differences
between the streamwise and transverse directions. The translational
auto-correlations and PDFs provide evidence for periodicity in the particle's
dynamics even under turbulent conditions. The angular autocorrelations show
weak periodicity. The angular accelerations exhibit wide tails, however without
a directional dependence.
