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Bring on the Heat: Thermal Imaging with the NXT

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Lookin' Hot!I built a pan and tilt rig for the Dexter Industries Thermal IR Sensor with a great deal of gearing down to allow me to take a lot of measurements as the rig moved around. Initially I had it set for about 40×40 measurements but those didn’t look that great and I wanted a bit more. I reprogrammed it and made it spit out data at a resolution of about 90×80.

The data from the thermal sensor was streamed to the debug output console in ROBOTC from which I copy and pasted it to an Excel worksheet.  I made some 3D graphs from the thermal data and it looked pretty cool.

Excel graph for cold glass Excel graph for candle flame

The left one is a cold glass and the right one is a candle.  I wasn’t really happy with the results of the graphs so I decided to quickly whip up a .Net app to read my CSV data and make some more traditional thermal images.  A few hours later, the results really did look very cool.

Thermal image for cold glass Thermal image for candle flame

Again, the left one is the cold glass and the right one is the candle.  Now that you have a thermal image, you can see the heat from the candle a lot more clearly. I made a quick video of the whole rig so you can get an idea.

A few days after the initial post about my thermal imaging system using the Thermal Infrared Sensor, I made some improvements with both the speed and accuracy of the whole thing. I made the sensor sampling interval time based, rather than encoder value based. This proved to be a lot better at getting consistent sampling rates. I also doubled the horizontal motor speed so I would be more likely to be still awake by the time it was done taking an image.

The left image was made with the old system, the right one with the new system. It’s a lot less fuzzy and there are no black gaps where the number of samples were fewer than the maximum number of samples in a row.

image_thumb7 image_thumb8

Perhaps there are other ways to improve the program but I am quite happy with how this has turned out.

The driver and program will be part of the next Driver Suite version. You can download a preliminary driver and this program from here: [LINK].  The .Net program and CSV files can be downloaded here: [LINK]. You will need Visual Studio to compile it.  You can download a free (Express) version of C# from the Microsoft website.

Written by Xander Soldaat

June 16th, 2011 at 4:47 pm