GSD For Roof Thermals? Radiometric neccesity?

Anyone know what a good rule of thumb is for minimum GSD for a flat roof thermal image to identify heating/cooling leaks and/or water infiltration?  10cm/pixel? 5cm/pixel?

And how critical is it to use a radiometric camera when all you’re are doing is looking for significant temp differences and the accuracy of the actual temp isn’t that important?  Seems like radiometric would have the main benefit on something like power utility inspection where you need to have accurate temp readings?

 

I haven’t done such inspections myself, but if I had to select the GSD I’d check how big those leaks or infiltrations usually are. Then, I’d take a GSD that is at least half that size, so that you can detect the leaks. 

Here is a similar post on the subject: https://community.pix4d.com/t/4020

As for the radiometric vs non radiometric camera, one advantage of the radiometric camera is that you will have absolute temperatures, so you could search for leaks by searching temperatures directly. The other would be more approximative and maybe more a visual inspection. Make sure to create the reflectance map in the software to make this analysis. 

Hope it helps! 
Would be great to have some people doing thermal inspections commenting! :slight_smile: