A circular Gaussian autoregressive (CGAR) source is used as a model for closed planar curves. A class of suboptimal encoding schemes is considered which separately quantize the Fourier coefficients of the boundary. Application of rate-distortion theoretic techniques leads to parametric equations describing the optimal encoding bound. Interpretation of these equations establishes a sampling criterion and a computationally efficient transform encoding scheme for the suboptimal class. Several variants of this transform encoding scheme are suggested and compared to the encoding bound.