INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Radiometric Thermal Camera with SDK

Radiometric Thermal Camera with SDK

(OP)
Hello,

I'm writing some drivers for thermal cameras that we're planning on using for research and I'm noticing a lack of information from FLIR about what needs to be recorded. I'm getting the raw image data, but it doesn't have any calibration information, or anything that would allow values on the image to be assigned a temperature. Has anyone worked with capturing raw data from a thermal camera? I'm curious about what information I have to grab from the camera in order to make sure the data is useful.

Cheers,

RE: Radiometric Thermal Camera with SDK

Generally, that tends to fall into proprietary information, as that's presumably the very information that provides the value-added functionality of radiometric accuracy.

In general, the camera needs a minimum of calibrations against a uniform source at two temperatures. These establish a linear regression against the output counts. The offset is simply residual noise and radiometric background. The slope is the responsivity, typically, counts/radiance. If your camera outputs radiometric temperature readings, then it's also doing a inversion of measured radiance to get a radiometric temperature. If an emissivity is selected or defaulted, then the radiometric temperature is an estimated thermometric temperature. Because no detector is perfectly linear over its dynamic range, multiple calibration temperatures are usually collected so that the responsivity can be corrected over the detector's dynamic range.

For uncooled bolometric cameras, the thermal environment significantly impacts the apparent radiance measured by each pixel, and multiple calibration and camera temperatures are used to select the correct responsivity as a function of camera temperature and measured scene radiance.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Radiometric Thermal Camera with SDK

(OP)
Hello IRstuff,

This is a scientific/industrial camera designed to be used with custom built software compliant with genicam, so I'm expecting I can get everything I need (just not in as pretty an interface as what they sell).

I had another discussion on the EEVblog forums and talked through the registers I needed in order to get the metadata. It turns out that you can set the camera in either radiometric or thermal-linear mode. Thermal linear mode then returns an image who's individual pixels have values in K. That mode is possibly best and creates the most useful "images". It should be possible to go between radiometric and thermal-linear mode in post if you know all the coefficients used to calculate the temperatures. I think you can access the calibration info as well through the genicam interface (but don't quote me on that).

As to your comments on accuracy, yes, that's one thing we're realizing that we have to communicate to the researchers is that absolute accuracy is difficult to achieve, especially with varying conditions like those found outdoors. Scientific visual imagery is difficult and we're learning that thermal imagery is even worse since it behaves so very differently.

Cheers,

RE: Radiometric Thermal Camera with SDK

We're actually in the midst of developing an infrared radiometer, and the calibration is a huge deal. The only saving grace is that our operating environment will be very limited, so the calibrations required are somewhat fewer than for a general purpose radiometer.

I would also caution you to check the lens; the commercial uncooled sensor we purchased appears to have either haze or veiling glare in the optics, which can seriously mess with both spatial resolution and radiometric accuracy.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close