This article presents a geometric fusion algorithm developed for the reconstruction of 3D surface models from hand-held sensor data. Hand-held systems allow full 3D movement of the sensor to capture the shape of complex objects. Techniques previously developed for reconstruction from conventional 2.5D range image data cannot be applied to hand-held sensor data. A geometric fusion algorithm is introduced to integrate the measured 3D points from a hand-held sensor into a single continuous surface. The new geometric fusion algorithm is based on the normal-volume representation of a triangle which enables incremental transformation of an arbitrary mesh into an implicit volumetric field function.This system is demonstrated for reconstruction of surface models from both hand-held sensor data and conventional 2.5D range images. Key-words: Object Modelling; 3D Reconstruction; Geometric Fusion; Range Image Integration 1