A new night time sensor design for human settlements monitoring
- Paper number
IAC-06-B1.3.08
- Author
Dr. Giovanni Laneve, University of Rome "La Sapienza", Italy
- Coauthor
Dr. Marco M. Castronuovo, Italian Space Agency (ASI), Italy
- Coauthor
Eng Enrico Giuseppe Cadau, University of Rome "La Sapienza", Italy
- Year
2006
- Abstract
In the mainframe of the EU funded Network of Excellence (NoE) GMOSS (Global Monitoring for Stability and Security) the University of Rome is studying the limits of applicability of nighttime satellite images for the detection and occupancy monitoring of human settlements and assessment of damages caused by natural disasters. In particular the regions considered for this application are Central Africa, concerning mainly refugee camps, and Kashmir, especially in consideration of the recent (Oct. 2005) earthquake event. A validation of the results will be performed using high- resolution images. Presently, few sensors operating at night are available for this purpose in the visible/near infrared part of the spectrum (DMSP/OLS, SAC-C/HSTC). In the case of DMSP/OLS, for instance, the sensor’s sensitivity is sufficient to detect villages characterised by artificial illumination typical of a western urban settlement of at least 4,000 people. This makes it difficult the exploitation of these data for the monitoring of settlements with reduced artificial lights, as is often the case in the selected regions of interest. Moreover, in many cases, as for informal settlements following the occurrence of natural or man-made disasters, only the presence of bone-fires could reveal the presence of a human community. As a consequence, it would be necessary to observe the affected areas using wavelengths in the TIR region of the spectrum (~ 4 mm), which is presently not feasible due to the limited sensitivity of available sensors. To overcome the difficulties described above, the University of Rome is carrying out a design analysis of a new nighttime sensor. The study is based on accurate simulations of the expected radiance scenario reaching the sensor. This, in fact, is required to assess the characteristics of a new sensor capable of detecting the desired target sources (lights/bone-fires). The night scenes simulations are performed by means of a state-of-the-art commercial software package and in-house developed programs. For this purpose, suitable radiative maps reproducing as accurate as possible the ground scenario related to human settlements are produced. The creation of this scenario is obtained through a step processing that can be summarised as follows. A satellite image of the desired area is used as input of a classification process that produces a map in which to each pixel a suitable mixture of materials, with known thermo-optical characteristics, is associated. In some case, the same satellite image can be used to produce the corresponding Digital Elevation Model and eventually a surface temperature map. Alternatively, the elevation information must be obtained from a different source. The obtained scene represents the background scenario where the target lights and bone-fires must be implanted. This is done adding, at given positions, user-defined objects with thermo-optical properties reproducing those of the desired targets. Starting from all these inputs, the mentioned software package produces a radiance map at sensor, with a user-defined spatial and spectral resolution and in accordance with a given atmospheric model. On the base of the radiance pattern reaching the sensor height, a design process is carried out in order to optimise the contrast between the targets and the background.
- Abstract document