Abstract. Recently modern non-Euclidean structure and motion estimation methods have been incorporated into augmented reality scene tracking and virtual object registration. We present a study of how the choice of projective, affine or Euclidean scene viewing geometry and similarity, affine or homography based object registration affects how accurately a virtual object can be overlaid in scene video from varying viewpoints. We found that projective and affine methods gave accurate overlay to a few pixels, while Euclidean geometry obtained by auto calibrating the camera was not as accurate and gave about 15 pixel overlay error.