The simplest approach for image acquisition over relatively
planar surfaces mimics the approach of collecting traditional stereoscopic
aerial photographs where images are collected in a
continuous line with a camera position orthogonal to the surface of
interest and with a frequency to produce image overlap >60%
(Fig. 3). However, the scale and layout of the target surface will
frequently necessitate adjustments to this simple approach.
Furthermore, James and Robson (2014) document systematic errors
that can be introduced across models derived from image collections
where all photos are collected with parallel viewing directions.
This error is manifest in the axis parallel to the image view
direction, for example producing broad-scale elevation error from
images collected with a vertical orientation. James and Robson
(2014) demonstrate that one approach to mitigate this systematic
error by combining additional images with a view direction that is
inclined relative to the view direction of the rest of the image
collection (Fig. 3)