GM7VEC HebCam

A delightful look into the skies above North Uist

I want to share with you Hebcam http://hebcam.uk/

Hebcam is something of a labour of love….no not for me, although I do love watching it, but for Stuart GM7VEC and Peter G7RPG.
For Stuart, it was his desire to share the wonders of our skies and weather systems and for Peter the challenges of learning new technologies to make it all possible.

So why did Stuart create the hebcam? Who better than Stuart himself, to explain his vision.

Well years ago I use to take stills of clouds with Infrared film and when I started doing timelapse last year I was reminded how fascinating cloud formation was especially at 30fps.
I bought a security camera and set it up at the cottage to just do still images but really wanted to add timelapse.
I chatted with Peter G7RPG and even using my Mac it wouldn’t process the images quick enough, up to 20mins in 4k on my Mac and that’s just for a 3min timelapse.
Anyway, Peter suggested renting a commercial server on Linux to do the hard work and with Peter finding the software lines it’s now working flawlessly.
People notice clouds every day but hardly give them a second thought.
But when you see the band’s of rain moving over the sky or the different direction the clouds move at different heights it makes it more interesting.
You’ll also notice the different forms of cloud and at speed see the influence the jet stream has on our weather.
Most of the storms come over from the west and northwest Atlantic because the sea is usually a constant temperature and that creates the energy in the winds we get from the west.
This link may explain the clouds and the heights that they form at.
https://scied.ucar.edu/webweather/clouds/cloud-types.
Finally, you get the odd ‘ Daylight Shooting Star’ vapour trail, which again you only normally notice for a moment when you look up.

Stuart GM7VEC

Not only is hebcam a source of some amazing sunsets and cloud formations but it is also very educational. You can observe how clouds at different heights move in opposite directions, as influenced by the jet streams.

While we all gaze lovingly at the amazing images, what we don’t realise is what goes on behind the scenes. I caught up with Peter G7RPG who explained the setup and software that makes hebcam look as amazing as it does.

The hebcam is a Hkivision 4K wide angle PoE camera. The website is hosted on a Linode VPS in a London DC (Data Centre). All the back end is done with bash scripts that run as systemd units so they can be started and stopped at given times. The first part of the process is to grab a single jpg frame from the camera using wget, these go into a folder and each image is time date stamped as the filename. This happens every 3 seconds in a loop. The next script runs in a 15minute loop to create the 15-minute stills throughout the day. It picks the last but one single frame from the image folder passes it through mogrify (part of ImageMagick) to correct the barrel distortion of the wide angle lens, overlays a transparent privacy layer to hide the road and car park and finally annotates the image along the bottom of the image. The time-lapse videos are made using another script that deletes files in the single image folder older than 2hours, then runs ffmpeg to make an mp4 video from the stills. ffmpeg is also passed a parameter to correct the lens distortion and adds the privacy overlay. All the scripts are controlled by the sunrise/sunset times which is generated each day using a little free utility called Sunwait.
The camera updates a noip.org dynamic DNS hostname so the server can find the camera.
At the end of each day, all the videos and 15min stills are moved to an archive and the remaining stills are deleted.

Peter G7RPG

This is the raw unprocessed image from the camera with no lens correction or privacy mask.

Raw unprocessed image direct from the camera

And here is what it looks like after all of the processing

As seen on the live site with privacy mask and correction

So as you can see, a lot of work goes on behind the scenes to make the images look as perfect as they do. I want to take this opportunity to say thanks to Stuart and Peter for their work on hebcam, I hope many people find joy and education from it.