The Heat Map

February 5th, 2013

It’s years ago now, but I remember being really inspired by a long exposure of a street, with a line of light meandering up and down it.  It wasn’t that it was visually exciting, but that the height of the line represented the strength of the local wifi signal.  More than just a pretty picture, this was a graph of something abstract that related directly to the geography, and it was immediately engaging.  I’ve been caught up with the idea of doing something like that myself ever since, and I finally did something about it.


I decided to map temperature gradients visually.  Specifically, in drains.

So, I built something.  It’s a box with temperature sensors (I went through three before I found one responsive and sensitive enough) and a bright colour-shifting light.  It has a few buttons for setting upper and lower temperature bounds, choosing colours for warm and cool extremes, and for pulsing the light for the sake of photography.

The current temperature is read, and based on where it falls between the bounds, the light is set to a corresponding colour between its selected extremes.  So, the idea is that the pattern of lights will transition between colours, bringing the abstraction of temperature shift into concrete visual existence.

In practice, of course, there were hiccups, and things that worked fine in testing didn’t work so perfectly in the field.  Most notably, the gradual shift for some reason became a hard change between the extremes, which was a problem I’d encountered in development but thought was resolved (both through software fixes and using a temperature gauge with higher precision).  Still, I was pleased enough to get a basic result.

It took a few iterations to come up with an approach that was actually visually appealing.  Throwing lights at drains gets complicated rapidly, and doesn’t always lead to pleasant results.  I’ve had a few other suggestions thrown my way while working on this, like mapping surface rather than air temperature, or reflecting drain dimensions visually, but those will take some thought yet.

For all the tedium of experimenting and reworking, it’s good fun.

Probably needs more lasers, though.

2 Responses to “The Heat Map”

  1. Tigzon 05 Feb 2013 at 1:47 pm

    I don’t get it…

  2. Svenon 05 Feb 2013 at 1:50 pm

    Basically, it was slightly warmer inside the tunnel than outside.

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