In preparation for deploying more systems in Iceland this summer – I updated our spare Piksi Multis and did a garden test. It performed very well!
I set them up to fix at 10Hz but report every 5 readings – so its closer to our slow system in Iceland. The fix hopped around within about 1.5cm – which is good for my garden as the sky box is not that wide.
These new dGPS units seem to be accurate to around 2cm as shown in our test. This is for a close baseline (and at the moment doesn’t use GLONASS).
We have deployed a Brinno TLC100 camera to monitor the flow in the outlet river from the glacier we work on, footage from this camera can be seen in a previous blog post. However, whilst being simple to set up the output from the camera is not particularly useful for analysis. It saves the images as an avi file, which is great for the amateur timelapse market, not so good for our purposes.
In order to fix this the file was first run through ffmpeg in order to get separate jpeg files for each image. However, this then let to the problem of how to extract the time stamp from the image. Image processing is not area but fortunately the openIMAJ team is based in the same building as us. I went and had a chat to Jon Hare asking if there was anything suitable available off the shelf, unfortunately the software available did not produce good results. So Jon went away and within a few hours he had written a custom piece of software to perform the OCR for us. I then wrapped this in a python script to process a folder and automatically rename the files with the timestamp and add the relevent data to the database.
Once the script had run we had a collection of about 900 images all the the correct timestamp for the file name, and included in the database to enable us to keep track of what times we had images for.
That was the simple part – the hardest part is yet to come – working out river depth from the images we now have.
Thanks to the daily camera image from the base station’s webcam we can see that the snow is starting to settle on the glacier.