Automatic　reconstruction　of　unknown　3-D　objects　has　been　of　great　importance　in　computer　vision,　pattern　recognition　and　visualization.　In　this　paper,　a　new　view　planning　approach　of　generating　3-D　models　automatically　is　proposed.　The　new　algorithm　incorporates　the　visual　region　of　the　vision　system　with　the　limit　visual　surface　of　the　unknown　model.　The　limit　visual　surface　is　modeled　according　to　the　knowledge　of　acquired　object　model.　And　the　space　positions　of　efficient　viewpoints　are　determined　according　to　the　visual　region　of　the　system　and　the　limit　visual　surface.　The　NBV　position　is　the　position　that　could　obtain　the　maximal　unknown　surface　area　among　the　efficient　viewpoints.　The　experimental　results　show　that　the　method　proposed　is　effective　in　practical　implementation.