In a virtual endoscopy method, an unfolding axis substantially along an elongated lumen is divided into axis segments. Ray casting directions are selected extending generally radially from the axis segments. At least some of the ray casting directions are tilted away from a camera position. Ray casting is performed along the tilted ray casting directions to define pixel values that are arranged into an unfolded view. The ray casting employs at least one of (i) volume rendering and (ii) computing a statistical characteristic of voxels over a preselected distance (dinterval) along the ray casting direction into the lumen-defining structure.