GroundBased Hyperspectral Image Surveillance Systems for Explosive Detection: Part IIxe2x80x94Radiance to Reflectance Conversions The usage of white references for reflectance conversion in a captured scene for potential groundbased hyperspectral image surveillance systems suffers from security, as it exposes the location of the system, and could be expensive for a broad application due to the high prices of standard Spectralons. In Part I of this twopart article, the stateoftheart of groundbased hyperspectral imaging systems for explosive trace detection was discussed along with the future challenges for generic surveillance systems. The part II of the article proposes different approaches for reflection conversion to compensate the usage of white references at every capturing instant during surveillance, which is one of the main challenges of these systems. As an initial approach, recording the radiance of white reference only at the initialization of the system is tested by capturing an experimental setup in different days and times throughout a duration of two months. The correlations between the incident lights obtained from white references at different times, days, and orientations are compared. The effects of using a prerecorded white radiance for the reflectance conversion in the current scene are investigated. Second, a practical approach for reflectance calculation is tested by employing cheapprice reference objects having smooth characteristics in shortwave infrared spectrum, instead of expensive Spectralons. Finally, a novel reflectance conversion method is developed by using the reflectance of the static background materials in the scene rather than standard references by considering the stationary characteristics of surveillance systems. The proposed approaches are compared and verified on the baseline detection methods.

A spectral imaging system for precision agriculture: From its inception till a precommercial prototype New trends in the development of tools and strategies to optimize the productivity of agricultural fields have led to exciting opportunities based on a combination of two key technologies: Unmanned Aerial Vehicles (UAVs) and spectral sensors. Both of them come from different domains, the former playing a significant role mainly in military applications, and the latter in the space sector. UAVs and earth observation satellites represent the two extremes of monitoring systems in which airborne and High Altitude Pseudo Satellites (HAPS) are located in the middle range. From these four options, UAVs represent a good compromise between cost, performance and ease of operation in their numerous civil and environmental applications. However, they are also very challenging mainly due to the integration of specific payload which requires engineering experience in optics, electronics, physics and aerodynamics. In this paper, a hyperspectral UAV platform is presented, detailing every decision adopted since its inception for its use in precision agriculture, solving the problems encountered in its construction and developing an adhoc application to control the flight trajectory and manage data acquisition optimizing its battery limitations. The result is a robust autonomous system tested in a real scenario to monitor the health status of a vineyard in just a few minutes, based on different Vegetation Indices (VIs), reducing the time and efforts employed by traditional farmers and opening new avenues in the management of agricultural production and environmental respect.