Thermal cameras and applications: a survey <s> Building inspection <s> A nondestructive thermal study has been developed in the present study using the infrared thermographic technique in heating ventilating and air conditioning (HVAC) applications. In these applications, evaluation of thermal patterns of large walls, barriers with their constructive elements, pipes and conduits of air conditioning and thermal systems, cables, wires, contact-breakers of electrical installations have been developed. The influence of humidity in thermal behaviour of building materials has been also studied. The results showed relationship between water evaporation and porosity due to material structure, and the work has shown the utility of this technique in detecting various non-visible defects in energetic and thermal installations. <s> BIB001 </s> Thermal cameras and applications: a survey <s> Building inspection <s> In recent years, very high energy consumption is the major problem of the big cities. Most of the energy of the cities are disbursed to warm and cool buildings. Thus, detecting heat leakages on building walls is a new research problem. In this study, we propose a novel system to detect thermal leakages automatically from thermal camera images. To this end, we use sequential thermal images of buildings. First, we start with fusing thermal image sequences to obtain rectified building facade with higher resolution. Then, we detect L-shaped features using a set of steerable filters. We use L-shaped features and perceptual organization rules to detect windows and doors from rectified thermal image. After eliminating detected doors and windows from building facade, we detect problematic regions. One of the advantage of proposed system is that, it can also be used to detect building damages automatically even in night time. Therefore using proposed system, it may be possible to detect thermal leakages and also damages by only using images taken from a vehicle which is moving around interested buildings. <s> BIB002 </s> Thermal cameras and applications: a survey <s> Building inspection <s> Roof Leakage is the major problem faced in almost all buildings irrespective of the age of the building. Basically, roof leak is caused because of the different conditions and material used in construction. But most of the time these leakages are so small that we cannot see with bare eyes. That's why infrared cameras are used for detecting roof leaks. Based on the images captured by infrared cameras, edge map is drawn and that particular area is repaired. Because of the thermal nature of the infrared image, we cannot see edges perfectly which makes us to use approximation of an edge. This leads to the wastage of the material used in repairing the roof leaks which in turn increases the cost of repair also. This paper presents a technique of infrared image enhancement for roof leakage detection. This technique combines the benefits of homomorphic image processing and the additive wavelet transform. The idea behind this technique is to decompose the image into three sub bands in an additive fashion using an additive wavelet transform. The homomorphic processing is performed on each sub band, separately. The homomorphic processing transforms the image into illumination and reflectance components. Butterworth filter is used to enhance the reflection and illumination components in the image, separately. Finally, an inverse additive wavelet transform is performed on the homomorphic enhanced sub bands to get an infrared image with better visual details as well as edge map. <s> BIB003
Thermal cameras have been used for years for inspecting heat loss from buildings, and special hand-held imaging devices have been developed with this application in mind. Figure 9 shows an example of a thermal image of a building. Normally the inspection of buildings requires manual operation of the camera and interpretation of the images to detect heat loss, e.g. as described in BIB001 . More automatic methods are also being investigated. In [119] , an Unmanned Aerial Vehicle (UAV) is used for inspection of buildings, and the system automatically detects the heat loss from windows. Another system has been proposed, which automatically maps the images to a 3D model, eliminates windows and doors, and detects regions with high heat loss on the facade [69, 77, BIB002 . A thermal system has also been proposed for detecting roof leakage BIB003 . Besides the detection of heat loss, thermal imaging has also been used to detect other problems behind the surface: Li et al. [113] proved that thermal imaging can be used to detect debonded ceramic tiles on a building finish. Termites can also be found by inspection with a thermal camera, as they produce unusual heat behind the surface in buildings [79] . For some ancient buildings, it is of interest to monitor the wall's hidden structure, the surface status, and moisture content, which can be done with a thermal camera [60] . The documentation of a building's status can also be done by combining visual and thermal images [106] . Another interesting application related to buildings is the one presented in the book Mobile Robot Navigation with Intelligent Infrared Image [44] . They present an outdoor robot system equipped with a thermal camera and an ultrasound sensor. In order to move around safely, the robot should be able to classify typical outdoor objects, such as trees, poles, fences, and walls, and make decisions about how to go around them. The classification of these non heat-generating objects is based on their physical properties, such as emissivity, that influence their thermal profile.