This paper provides an overview of research in search and detection modeling of military imaging systems. For more than forty-five years the US Army Night Vision and Electronic Sensors Directorate (NVESD) and others have been working to model the performance of infrared imagers in an effort to link imaging system design parameters to observer-sensor performance in the field. The widely used ACQUIRE model accomplished this by linking the minimum resolvable contrast of the sensor to field performance. From the original hypothesis put forth by John Johnson in 1958, to modeling time limited search, to modeling the impact of motion on target detection, to modeling target acquisition performance in different spectral bands, search has a wide and varied history. This paper will first describe the search-modeling task and then give a description of various topics in search and detection over the years. Some of the topics to be discussed will be classic search, clutter, computational vision models and the ACQUIRE model with its variants. It is hoped that this overview will provide both the novice and experienced search modeler alike with a useful summary and a glance at current issues and future challenges.

Context. A complex environment exists in the inner few astronomical units of planet-forming disks. High-angular-resolution observations play a key role in our understanding of the disk structure and the dynamical processes at work. Aims. In this study we aim to characterize the mid-infrared brightness distribution of the inner disk of the young intermediate-mass star HD 163296 from early VLTI/MATISSE observations taken in the L- and N-bands. We put special emphasis on the detection of potential disk asymmetries. Methods. We use simple geometric models to fit the interferometric visibilities and closure phases. Our models include a smoothed ring, a flat disk with an inner cavity, and a 2D Gaussian. The models can account for disk inclination and for azimuthal asymmetries as well. We also perform numerical hydrodynamical simulations of the inner edge of the disk. Results. Our modeling reveals a significant brightness asymmetry in the L-band disk emission. The brightness maximum of the asymmetry is located at the NW part of the disk image, nearly at the position angle of the semimajor axis. The surface brightness ratio in the azimuthal variation is 3.5 ± 0.2. Comparing our result on the location of the asymmetry with other interferometric measurements, we confirm that the morphology of the r < 0.3 au disk region is time-variable. We propose that this asymmetric structure, located in or near the inner rim of the dusty disk, orbits the star. To find the physical origin of the asymmetry, we tested a hypothesis where a vortex is created by Rossby wave instability, and we find that a unique large-scale vortex may be compatible with our data. The half-light radius of the L-band-emitting region is 0.33 ±0.01 au, the inclination is 52°−7°+5°, and the position angle is 143° ± 3°. Our models predict that a non-negligible fraction of the L-band disk emission originates inside the dust sublimation radius for μm-sized grains. Refractory grains or large (≳10 μm-sized) grains could be the origin of this emission. N-band observations may also support a lack of small silicate grains in the innermost disk (r ≲ 0.6 au), in agreement with our findings from L-band data.

Both WFG and WFO PRK results translate to excellent and comparable visual and military performance.