  Image-based 3D reconstruction or 3D photogrammetry of small-scale objects
including insects and biological specimens is challenging due to the use of
high magnification lens with inherent limited depth of field, and the object's
fine structures and complex surface properties. Due to these challenges,
traditional 3D reconstruction techniques cannot be applied without suitable
image pre-processings. One such preprocessing technique is multifocus stacking
that combines a set of partially focused images captured from the same viewing
angle to create a single in-focus image. Traditional multifocus image capture
uses a camera on a macro rail. Furthermore, the scale and shift are not
properly considered by multifocus stacking techniques. As a consequence, the
resulting in-focus images contain artifacts that violate perspective image
formation. A 3D reconstruction using such images will fail to produce an
accurate 3D model of the object. This paper shows how this problem can be
solved effectively by a new multifocus stacking procedure which includes a new
Fixed-Lens Multifocus Capture and camera calibration for image scale and shift.
Initial experimental results are presented to confirm our expectation and show
that the camera poses of fixed-lens images are at least 3-times less noisy than
those of conventional moving lens images.
