Moving imagery from a static scene was recorded with an uncooled thermal imager at nine different angular velocities ranging from 0 (static) to 1 pixel/frame (3.75 deg/s) using a tilted rotating mirror. The scene contained a thermal acuity test chart with triangular test patterns based on the triangle orientation discrimination (TOD) test method. The imagery was processed with different types of image enhancement: dynamic super-resolution (DSR), local adaptive contrast enhancement (LACE), and combinations. DSR shows a significant performance improvement at low velocities, a moderate improvement at medium velocities where smear becomes apparent, and no benefit at high speed. Performance with LACE is close to optimized gain and level setting by hand. Static performance and dynamic performance at 0.57 pixel/frame containing significant smear were compared with earlier published identification performance data for two-hand held systems collected under a variety of signal processing conditions. It shows that the ratio M75 between the 75% correct threshold size for the two-hand held objects and the TOD triangle is preserved under all conditions measured. Thus, TA range prediction based on the TOD is robust against a complex combination of conditions, including motion, smear, and the types of image enhancement applied.
The construction and validation of soldier combat models requires data on the conspicuity of camouflaged targets in the
field, and human targets in particular. So far, this data is lacking. Also, it si currently unknown to what degree luminance
contrast and motion contribute to target conspicuity. These data are needed to enable the validation and further
development of human visual search performance modules in soldier combat models like SCOPE or IWARS. In this
study we measured the conspicuity of a person wearing a Dutch army camouflage uniform, while he was either standing
still, walking or running along a forest in the background, both for viewing with the naked eye (NE) and for viewing
dynamic thermal scene recordings (IR). We varied the viewing distance (80m and 230 m), the camouflage pattern
(woodland and desert), the type of background (pine-tree and deciduous forest), and season (summer and winter), The IR
(thermal) conspicuity of the person was much larger than his NE (visual) conspicuity. In both cases the effects of
movement were large and saturated as a function of retinal target speed. For NE, we find large effects of shading that can
not explained by local luminance contrast variations. Also for NE, conspicuity was reduced in winter, probably as a
result of an increase in scene clutter. The results suggest that conspicuity is not only a function of retinal target motion
and global luminance contrast, but also depends on the amount of clutter in the scene.
Moving imagery from a static scene was recorded with an un-cooled thermal imager at nine different angular velocities
ranging from 0 (static) to 1 pixel/frame (3.75 deg/s) using a tilted rotating mirror. The scene contained a thermal acuity
test chart with triangular test patterns based on the Triangle Orientation Discrimination (TOD) test method. The imagery
was processed with different types of image enhancement: DSR (Dynamic Super Resolution), LACE (Local Adaptive
Contrast Enhancement) and combinations. DSR shows a significant performance improvement at low velocities, a
moderate improvement at medium velocities where smear becomes apparent and no benefit at high speed. Performance
with LACE is close to optimized gain and level setting by hand. Static performance and dynamic performance at 0.57
pixel/frame containing significant smear were compared with earlier published identification performance data for twohand
held systems collected under a variety of signal processing conditions. It shows that the ratio M75 between the
75% correct threshold size for the two-hand held objects and the TOD triangle is preserved under all conditions
measured. Thus, TA range prediction based on the TOD is robust against a complex combination of conditions,
including motion, smear and the types of image enhancement applied.
In an extensive Target Acquisition (TA) performance study, we recorded static and dynamic imagery of a set of military and civilian two-handheld objects at a range of distances and aspect angles with an under-sampled uncooled thermal imager. Next, we applied signal processing techniques including DSR (Dynamic Super Resolution) and LACE (Local Adaptive Contrast Enhancement) to the imagery. In a perception experiment, we determined identification (ID) and threat/non-threat discrimination performance as a function of target range for a variety of conditions. The experiment was performed to validate and extend current TA models. In addition, range predictions were performed with two TA models: the TOD model and NVThermIP. The results of the study are: i) target orientation has a strong effect on performance, ii) the effect of target orientation is well predicted by the two TA models, iii) absolute identification range is close the range predicted with the two models using the recommended criteria for two-handheld objects, iv) there was no positive effect of sensor motion on performance, and this was against the expectations based on earlier studies, v) the benefit of DSR was smaller than expected on the basis of the model predictions, and vi) performance with LACE was similar to performance on an image optimized manually, indicating that LACE can be used to optimize the contrast automatically. The relatively poor results with motion and DSR are probably due to motion smear induced by a higher camera speed than used in earlier studies. Camera motion magnitude and smear are not yet implemented in TA models.
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