Three dimensional volume data sets provided by CT or MRI allow the user to move virtually around within anatomic structure and to observe them. We propose a new method to guide the path planning based on the local image interpretation during the navigation inside the anatomic structures with cavities, without preprocessing for 3D volume data sets. Thanks to the scene analysis process, the virtual sensor constructs by itself a model of the unknown scene. Qualitative and quantitative characterization of the anatomic structures, derived from this exploration, is of main interest in such a new application of virtual endoscopy that is vascular surgery. In this paper we especially describe the scene analysis process which is based on the processing of the depth map directly produced by the ray casting procedure. Application to vascular surgery, i.e. virtual angioscopy, is then depicted.
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