Figure 2
From: Tracking objects outside the line of sight using 2D intensity images
Intensity difference images.
To investigate the effect of changes in object position and orientation on the intensity distribution observed on the wall, we performed a simplified synthetic experiment with an orthographic view of a 2 m × 2 m wall and laser spot and object centered with respect to the wall. The reference distribution (bottom left) was produced by a 10 cm × 10 cm square-shaped object, located at 50 cm from the wall. Six difference images (top row), obtained by translating (±2.5 cm) and rotating (±7.5°) the object about the X, Y and Z axes, illustrate the distribution and magnitude of the respective change in the signal. The images shown in the bottom row visualize the difference caused by a change in shape. For display, each difference image has been amplified by the indicated factor (2 to 100,000) that also reflects the relative significance of the effect: Translations and rotations (except around the Y axis) caused the signal to change by roughly 1% per centimeter or per angular degree. A change in the object shape led to a peak difference around 1–2% and rotation around the Y axis had a much smaller effect.
