lens can be integrated or not. Many models do not provide the irradiance measurements used to construct the output image; the loss of this information without a correct calibration for emissivity, distance, and ambient temperature and relative humidity entails that the resultant images are inherently incorrect measurements of temperature. Images can be difficult to interpret accurately when based upon certain objects, specifically objects with erratic temperatures, although this problem is reduced in active thermal imaging. Thermographic cameras create thermal images based on the radiant heat energy it receives. As radiation levels are influenced by the emissivity and reflection of radiation such as sunlight from the surface being measured this causes errors in the measurements. Most cameras have ±2% accuracy or worse in measurement of temperature and are not as accurate as contact methods. Methods and instruments are limited to directly detecting surface temperatures. Applications Condition monitoring Low slope and flat roofing inspections Building diagnostics including building envelope inspections, moisture inspections, and energy losses in buildings Thermal mapping Digital infrared thermal imaging in health care Medical imaging Non-contact thermography, contact thermography and dynamic angiothermography Peripheral vascular disease screening. Carotid artery stenosis (CAS) screening through skin thermal maps. Active Dynamic Thermography (ADT) for medical applications. Neuromusculoskeletal disorders. Extracranial cerebral and facial vascular disease. Thyroid gland abnormalities. Various other neoplastic, metabolic, and inflammatory conditions. Archaeological kite aerial thermography Thermology Veterinary Thermal Imaging Thermal imaging in ornithology and other wildlife monitoring Night vision and Targeting UAV Surveillance Stereo vision Research Process control Nondestructive testing Surveillance in security, law enforcement and defence Chemical imaging Volcanology Building Thermal imaging cameras convert the energy in the infrared wavelength into a visible light display. All objects above absolute zero emit thermal infrared energy, so thermal cameras can passively see all objects, regardless of ambient light. However, most thermal cameras only see objects warmer than . The spectrum and amount of thermal radiation depend strongly on an object's surface temperature. This makes it possible for a thermal imaging camera to display an object's temperature. However, other factors also influence the radiation, which limits the accuracy of this technique. For example, the radiation depends not only on the temperature of the object, but is also a function of the emissivity of the object. Also, radiation originates from the surroundings and is reflected in the object, and the radiation from the object and the reflected radiation will also be influenced by