We propose a novel algorithm for unsupervised extraction of piecewise planar models from depth-data. Among other applications, such models are a good way of enabling autonomous agents (robots, cars, drones, etc.) to effectively perceive their surroundings and to navigate in three dimensions. We propose to do this by fitting the data with a piecewise-linear Gaussian mixture regression model whose components are skewed over planes, making them flat in appearance rather than being ellipsoidal, by embedding an outlier-trimming process that is formally incorporated into the proposed expectation-maximization algorithm, and by selectively fusing contiguous, coplanar components. Part of our motivation is an attempt to estimate more accurate plane-extraction by allowing each model component to make use of all available data through probabilistic clustering. The algorithm is thoroughly evaluated against a standard benchmark and is shown to rank among the best of the existing state-of-the-art methods. 2013), or any other similar device.Recently, dense depth-data have become readily available due to the development of affordable structured light and time-of-flight cameras. Each of these sensor-types produces images of depth-related values that can be projected as clouds of 3D points. These point-clouds, however, are nothing more than a noisy set of points that only sample the environment. The observer must then be able to make sense of these observations by using them to construct a model of some form, e.g. a set of planar surfaces.An alternative to a piecewise-planar model might be to attempt to represent the environment as a set of known objects. To do so, however, comprehensive objectrecognition training would be required. In practice, in a dynamic, real-world environment, such a technique would ultimately only be able to complement a more general, unsupervised approach. Planar primitives are sufficiently general to model most environments. They are particularly appropriate in the home and office, where planar surfaces are prevalent, but can also handle more complex scenes, approximating curved surfaces in a piecewise fashion. Although a piecewise planar representation of the environment may not allow many objects to be iden-