Continuing with my previous post about “Not upto the mark” technical specification for human body screening system in India, I thought I would try to put up specifications which are minimum technical requirement for such systems. It may not be complete and totally exhaustive list, but I think this could be good enough to start with.
- It should be dual camera system ie It should have both Thermal Camera and Visual Camera. Why ? Because : Thermal camera is to measure human body ( face skin) temperature measurement and the visual camera for face detection. Face Detection and Face Recognition are two different thing altogether and should not be confused with one another. Automatic face detection helps identify the person who has high body temperature.
- Thermal Camera resolution must be 384X288 Pixels or higher, Why ? While Thermal Cameras with both 80X80 pixels and 160X120 Pixels may be able to detect high body temperature in a human face which is of approx 8-14CM width and 10-17CM in height ( just a general figure) with suitable length, but 384X288 Pixels will out form and offer more flexibility than 160X120 Pixels / 80X80 Pixels ones. Higher resolution Thermal camera require at least 1GBPS Ethernet which may be expensive.
- Thermal Camera should be able to measure temperature from 20 to 50 Degree C.
- The accuracy of temperature measurement should be minimum +/- 0.5 Degree C without black body (Reference Object with a black surface of fixed temperature) and should be +/- 0.4 Degree C with a Black Body. This specification simply says that, the measured temperature error could be upto 0.8 Degree with black body and upto 1 degree without black body. This accuracy should provide enough indication of a person who has high body temperature which may require further medical investigation to ascertain presence of fever. Very important to note here is, all industrial Thermal Cameras had normally accuracy of +/- 2 Degree C before pre-covid19 era! Also, this accuracy should be maintained at ambient temperature from 20 Degree C to 50 Degree C, depending on the location where the Human Body Temperature Screening is being deployed. In open area in northern India like an entry gate in a power plants ( or any othe rplants), factories, the ambient temperature could rise upto 45 Degree C during days and goes below 25 Degree C. But while installing inside air conditioned airport building, malls, office entrance , it could be pleasant ambient temperature at 28 Degree C or less.
- Operating Temperature should be from 0 Degree C to 50 Degree C and it should be customised depending on area/location of deployment. The accuracy of the Thermal Camera should remain same.
- Certificate of temperature measurement accuracy from an NABL ( National Accreditation Board for Testing and Calibration Laboratories) Accredited laboratory should be a must. Without this, most probably, the temperature measurement would be just an eyewash and could put people at risk.
- Thermal camera should have spectral range of 8014 Micron and should have NEDT less than <40mK at f1.0, 30 Hz 300K. This specification is an indicator of the temperature measurement accuracy. It could be cooled or un-cooled.
- Lens FOV ( Field Of View) for thermal camera should be around from : H:22 to 50 Degree V: 18 Degree to 40 Degree.
- Visual Camera should be industrial grade as normally all thermal cameras are of industrial grade. It should have at least 1.3MP so that face detection or any other image processing becomes easier.
- Both these cameras should be housed in a proper enclosure ( preferably IP65) so that they have same over-lapping FOV which will be the measurement area.
- Thermal and Video camera should have preferably Ethernet connectivity so that it can be monitored from a distance or videos could be taken to a control room with ease.
- PC based Windows or Linux Software which is capable of live video display, or optional face detection, saving image and temperature data and generate alarms when any high body temperature, say 37.5 Degree C is detected.
- The software should have configurable emissivity option. This could be important when people wear heavy make-up on face. It is good idea to have face detection facility in the software but that is not a must.
- Black-body is a desirable and should be useful in an airport, malls etc. It may not be very useful for plants, factories without arranging proper shade for it.
I have tried to mention some technical specification for human body temperature screening system here and I welcome everyone to add their desirable or expected specification in the comment section.