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Public Lab Wiki documentation



Thermal photography

This is a revision from February 16, 2012 20:17. View all revisions
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Applications

Thermal imaging can be used to document heat/AC leaks from insulation gaps on a building's facade, reveal warmer ground water inflows (either fresh or chemical-laden) or "thermal pollution" from industrial processes entering ocean-temperature waterbodies, as well as identify areas on the human body experiencing infection or stress (includes epidemiological applications).

Community applications so far include both a "heat-busters" program in East Harlem and a "forensic" water quality monitoring program in the Gowanus Canal.

Approaches

There are three prototypes in development:

  • A Thermal Flashlight (described on this page): a RGB LED flashlight with a non-contact infrared sensor that "paints" the temperature of the surface directly on the wall for capture with a second timelapse camera.
  • Thermal Fishing: dragging a thermometer through the water, taking contact measurements mapped to a RGB light, also for capture with a second timelapse camera.
  • A scanning thermal camera on a lego turntable (software also in development) that sweeps back and forth across a scene, recording the temperature variation to build up an image.

Problem

"FLIR" cameras can produce images such as the one below, and are typically used to identify heat leaks, but even low-resolution FLIR cameras can cost thousands of dollars. Our goal is to make this kind of investigation (and the potential savings) cheap, easy, fun, and informative for those of us without $10k in our pockets.

FLIR house

Thermal Flashlight

The first approach results in a kind of "light painting" -- a color heatmap overlaid directly onto the scene. This is the simplest, cheapest, and to date, most effective way we have developed of measuring heat leaks or cool leaks indoors and outdoors. Simply put, the "flashlight" puts out red light if it's pointed at something hot (default 75 deg F or more) and blue light if it's pointed at something cold *(default 60 deg F or less):

To capture the light painting over time, we have been using timelapse photography or GlowDoodle, as seen in the top image on this page.

Building your own

Parts list

Links to purchasing equipment:

Consumable Parts:

If you are starting an electronics kit from scratch:

  • a 40Watt soldering Iron (if you want it to be permanent otherwise duct tape or Velcro works temporarily)
  • hookup wire (solid not stranded- 22 or 24 gauge, you can get this at Radio Shack)
  • pliers called "wire strippers" to get the plastic wrap off the hookup wire (can get at Radio Shack)
  • solder for 40Watt iron, lead-free.
  • a breadboard (1 per flashlight). If you aren't soldering: http://www.adafruit.com/products/64. If you are soldering: https://www.adafruit.com/products/571.
  • a USB cable to connect the arduino to the computer via USB for power 5Volts (can get at Radio Shack)
  • household sponge for cleaning solder off tip
  • 9 volt battery with connector wires (can get at Radio Shack- 1 per flashlight)

Cost: ~$40-$60

These research notes will be integrated into this page to provide instructions on building and using your own thermal flashlight:

Several meetups have been organized to build and test thermal flashlights, at RISD (Providence, RI) and in Brooklyn, NY. We are organizing one now in Somerville, MA:

Thermal flashlight heatmaps