Chewin' Gum and Bailin' Twine
2013-04-12


My upgraded weather system has gone live.  It took some work to get there.

To summarize, my new home weather station includes a wireless LCD display, like the old one, but with more data fields (wind speed and direction, and precipitation).  Second, our cats frequently knock the data-capture camera out of position, forcing time-consuming recalibration.  The new version of the capture software makes it much easier to realign onscreen elements within the GUI environment.

It took trial, error, and plenty of arithmetic, but I'm getting the capture program fine-tuned, and the data are looking fairly reliable.  I do have to rejig the Humidex and Wind Chill calculation routines.  No biggie.  In the process, I've learned a lot about image processing.  For example, the webcam delivers a colour image, and I find that the green channel is the sharpest; so I use only the green values from the image.

The optical part of the data-capture process was the most time-consuming part.  I completely revamped how the system processes and validates the data from the LCD.  It now compares the average brightness for each character-segment against the brightness of a pre-selected control area for that character.  An adjustable darkness threshold allows tuning between false-negatives and false-positives.  One field is a differential value (current reading minus last reading), and another is a comparitive (select only the darkest of an array of segments).

The sky-observing software now outputs its results directly to the data-capture program, for integration into the data feed to the weather system itself.  Minutes of sunshine are imputed and recorded.

I've been tinkering with the weather software, to ensure it's properly recording and reporting the readings given it.

Looks good, so far.

-Bill