This work is concerned with buried landmines detection by long wave infrared images obtained during the
heating or cooling of the soil and a segmentation process of the images. The segmentation process is performed by
means of a local fractal dimension analysis (LFD) as a feature descriptor. We use two different LFD estimators,
box-counting dimension (BC), and differential box counting dimension (DBC). These features are computed in
a per pixel basis, and the set of features is clusterized by means of the K-means method. This segmentation
technique produces outstanding results, with low computational cost.
A great development of technologies for the detection of buried landmines took place worldwide in the last years. In
Argentina, a project for the development of an autonomous robot with sensors for landmines detection was recently
approved by the Science and Technology National Agency. Within this project we are studying the detection of
landmines by infrared radiation.
Metallic and plastic objects with landmines shape and dimension were buried at different depths from 1 to 4 cm in soil
and sand. Periodic natural warming by solar radiation or artificial warming by means of electric resistances or flash
lamps were applied. Infrared images were obtained in the 8-12 micrometers spectral band with a microbolometer
camera. The IR images were processed by different methods to obtain a definition as good as possible of the buried
objects. After this a B-Spline method was applied to detect the targets contours and determine shape and dimensions of
them so as to distinguish landmines from other objects.
We are looking for a landmine detection method as simple and fast possible, with detection capability of metallic and
plastic landmines and an acceptable false alarm rate which would be reduced when applied with other detection
methods as GPR and electromagnetic induction.
We present obtained and processed images and results obtained to distinguish buried landmines from other buried objects.
Presently, the number of landmines planted around the world totalizes more than 110 million and, far from slowing down,
the landmine production planting rate is, at least, one order of magnitude higher than the rate at which they are removed.
In this work a technique to detect buried landmines using boundary detection in IR images, is presented. The buried
objects have different temperature than the surrounding soil. We find the object contours by means of an algorithm of
B-Spline deformable curves.
Under a statistical model, regions with different temperatures can be characterized by the values of the statistical
parameters of these distributions. Therefore, this information can be used to find boundaries among different regions in the
The B-Spline approach has been widely used in curve representation for boundary detection, shape approximation,
object tracking and contour detection. Contours formulated by means of B-Splines allow local control, require few parameters
and are intrinsically smooth. The algorithm consists in estimating the parameters along lines strategically disposed
on the image. The true boundary is found when the values of these parameters vary abruptly on both sides. A likelihood
function is maximized to determine the position of such boundaries.
We present the experimental results, which show the behavior of the detection method, according to the buried object
depth and the elapsed time from the cooling initial time. The obtained results exhibit that it is possible to recognize the
shape of the objects, buried at different depths, with a low computational effort.
The wavelength, availability, range and power budget of an infrared free-space laser communication system critically depend on the atmospheric channel, which in turn is closely related to local weather conditions. As a result, the atmospheric propagation characteristics of the transmission medium must be taken into account from the beginning in the design of a free-space laser communication link. The most important linear effects that affect the attenuation of laser beam propagation through the atmosphere are absorption, scattering and turbulence. Weather parameters such as humidity, temperature and visibility are essential in determining the performance of a free-space laser communication system. Based on weather data recorded in Buenos Aires city (Argentina) at every hour during two years and made available to us by the Servicio Meteorologico Nacional (National Meteorological Service of the Argentinean Air Force), we calculate attenuation of laser radiation for an horizontal transmission path of 1 km for a near infrared direct detection optical communication system. Then, with these results, we estimate link availability and draw conclusions about when it is more convenient to transfer information.
A great development of technologies for the detection of buried objects took place in the last years. Applications in archeology, finding of pipe lines and others were important, but most attention was paid in humanitarian detection of land mines and unexploded ordnances. Among these technologies, thermography is one of the most useful techniques and has been applied concurrent with other ones (Ground Penetrating Radar, Electromagnetic Induction, etc.) We have made several experiments to obtain thermographic images of buried objects in the middle and far infrared, in laboratory and in field, and in different types of terrain: naked ground, ground covered with grass and sand. We employed, as warming methods, natural sun radiation and blowing of warm air or halogen lamps. We have used metallic and dielectric objects of different sizes and shapes so as to recognize them by their characteristics. The acquired images were improved using noise reduction and image enhancement techniques.
In this work we present the thermographic images obtained. All measurements were made at short distance, less than 100 cm, as the objective of our work is to develop a thermographic imaging system for the detection of buried objects to be installed in an autonomous ground robot.
Forest fires in summer and sheep buried under the snow in winter have become important problems in the south of our country, in the region named Patagonia. We are studying to find a solution by means of an airborne imaging system whose construction we have just finished. It is a 12 channel multispectral airborne scanner system that can be mounted in a Guarani airplane or in a Learjet; the first is a non- pressurized aircraft for flight at low height and the second is a pressurized one for higher flights. The scanner system is briefly described. Their sensors can detect radiation from the ultra violet to the thermal infrared. The images are visualized in real time in a monitor screen and can be stored in the hard disc of the PC for later processing. The use of this scanner for some applications that include the prevention and fighting of forest fires and the study of the possibility of detection of sheep under snow in the Patagonia is now being accomplished. Theoretical and experimental results in fire detection and a theoretical model for studying the possibility of detection of the buried sheep are presented.
The bonding of steel pieces and the development of novel soldering methods, appropriate to the extended variety of applications of steels nowadays, bring the sensing of temperature an outstanding role in any metallurgical process. Transient liquid phase bonding (TLPB) processes have been successfully employed to join metals, among them steels. A thin layer of metal A, with a liquids temperature TLA, is located between two pieces of metal B, with a liquids temperature TLB higher than TLA. The joining zone is heated up to a temperature T(TLA<T<TLB) and a bonded product with a near homogeneous composition is obtained. The most relevant parameter of the process is the bonding temperature T. The TLPB process for steel is performed in a 30 Kw induction furnace at temperatures in the range 800 degree(s)C to 1400 degree(s)C depending on the layer metal. A small window was opened between the central loops of the coil in order to observe the radiation emitted by the hot steel zone. A low price black and white CCD camera with 752x582 pixels has been adapted for temperature measurements through the coil of the furnace. The output of the camera is digitized and visualized in a 14-inch monitor. The temperature is calculated using the correlation with the gray tone present in the monitor, which is measured by means of suitable software. The technical specifications of the camera and the modifications introduced to adapt it for this work are presented. The calibration of the camera and the method employed in the measurements are described. The measured temperatures are corrected by the effect of emissivity of the materials surfaces and the environment radiation reflected. Thermographs obtained are shown and results are discussed. We conclude that a low priced camera may be used to measure temperature in this range with acceptable accuracy.
Thermographic measurements have been made from the air on a small electrical power distribution station situated in the country, near a village. The objective was to study the conditions of detection of possible failures in the electric elements of the station. For this purpose, thermal images were obtained with an infrared scanner in the 8 - 14 micrometer spectral regions from heights ranging between 300 and 1000 feet. The scanner was mounted in a Porter Pilatus aircraft. Thermographic images were obtained in gray tones or false colors. The apparent radiation contrast was evaluated at different hours in spring, summer and winter. Emitted and reflected radiation was considered under various atmospheric conditions. The emissivity coefficients of the electrical elements of the station and of the background were evaluated. Images selected are presented with results and conclusions.
IR thermal images of land, water surfaces and buildings have ben taken from an airplane by means of an IR scanner which has been previously described. The scanner was mounted in a Porter aircraft. Several flights have been made over a region of the province of Buenos Aires, in Argentine, in different days, at different times, under various climatic conditions. The height of the flights ranged from 100 meters to 500 meters, with 300 meters as the standard altitude. In every flight thermal images in the 8-14 micrometers spectral region have been acquired and stored for later analysis. Real time visualization of the images in a PC monitor allowed to select the images to be stored. We have analyzed image of buildings in villages, isolated buildings, water courses, water surfaces, roads and fields with different types of vegetation, in a region with a relative low density of population. Some thermal images and the conclusions of the thermal studies performed are presented.
A two channel scanning system for the visualization and storage of thermal images has been constructed. The system may be installed in aircrafts for the acquisition and storage of aerial images or used in surface for terrestrial images. Detection in the 3-5 micrometer spectral region with indium antimonide (InSb) detector and in the 8-14 micrometer spectral region with mercury cadmium telluride (HgCdTe) detector is provided in normal use; detection can be extended to near infrared by replacing In Sb detector by silicon or germanium detectors. Images are acquired in real time through an acquisition board, stored in the hard disk of a Pentium PC and displayed in a SVGA monitor. Characteristics of the system and the software developed are described. Some thermal images obtained are shown.