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Hedgehog camera

Posted on Mon 09 May 2016

I recently built a Raspberry Pi-powered hedgehog camera to view hedgehogs and other wildlife in my garden.

Screenshot

Hardware

Raspberry Pi

I actually tried a Pi 1 model A+ and a Pi 3 model B, and found no great difference in performance in this role, so I stuck with the A+ since it consumes less power and is smaller. You should be able to use any model which has the camera connector (all except the original Pi Zero).

Camera

I used a Raspberry Pi night vision camera - a 5MP infra-red camera module with IR LEDs - perfect for taking pictures at night, and also works well during the day.

Screenshot

WiFi dongle

I used a Long-range WiFi dongle with antenna - this allows the device to get a WiFi signal at the end of my garden so I can connect in.

Housing

After looking at various (very expensive) waterproof boxes, I opted for one from the supermarket - the kind used to store food. The ones with the rubber seal are very waterproof and should protect the electronics against adverse weather conditions.

I drilled a hole at the front of the box to allow the camera lens to fit through (although I left the LEDs inside). I placed blu-tack around the hole on the inside to prevent water ingress.

I also made an adapter which allows the box to be mounted on a tripod, although this probably isn't really necessary since it is fairly easy to position the box without this. I made this with a sheet of aluminium that fit into the bottom of the box, onto which I glued (using epoxy) a nut with the appropriate thread for a standard tripod (1/4-20 UNC). I drilled a hole in the aluminium sheet under the nut, and in the bottom of the box to allow the tripod thread to enter.

Power

I had originally intended to power the device using a large rechargeable power pack I had (10400mAh). This was able to power the Pi A+ and the WiFi dongle just fine for over a day. However, I found that the IR LEDs on the camera module were particularly power-hungry, and the battery would only last around 4-5 hours with those plugged in. I therefore decided to allow the device to be powered from the mains if required, so I made a small hole in the lip of the box near the plastic seal, to allow a USB cable to enter. I then ran this to a mains adapter placed in an appropriate water-resistant location.

Software

I started off by installing Raspbian on a 8GB MicroSD card, and enabled the camera from raspi-config.

pi-timolo

I installed pi-timolo - which stands for Pi Time lapse, Motion detect, Low light. This is an excellent and very configurable program which allows you to take pictures automatically when motion is detected, and/or at regular intervals.

VNC Server

I found the preview version of RealVNC Server for Raspberry Pi to be very useful in setting up the system, since it allows you to connect in and view the live camera image (by running the raspivid command). This allowed me to connect to the device in-situ from a tablet and focus the camera (by turning the lens on the front). This is shown in the following screenshot, which is actually taken on my desktop machine running VNC Viewer:

VNC Screenshot

Here I'm using the raspivid command to show a live preview from the camera:

$ sudo raspivid -t 0 -rot 180 -f

Run "raspivid --help" for a full list of the available options here. The "-t 0" option means to show the preview indefinitely, so use Ctrl-c to stop it when done. Only one application can access the camera at one time, so you must stop raspivid before running pi-timolo, and vice-versa. Note that I used "-rot 180" to rotate the image since I actually mounted the camera upside down due to the cable orientation! Pi-timolo has a similar option (flip horizontal and vertical) to achieve this.

ffmpeg

I found ffmpeg very useful for converting series of timelapse or motion-detection images into a single video file. An example command to do this is:

$ ffmpeg -f image2 -pattern_type glob -i '*.jpg' out.mp4

Use it

I placed the device in a suitable position at the end of my garden, where I had seen hedgehogs in the past. I then powered up the device and made sure the camera was focussed. I also put down some hedgehog food and a dish of water to try and draw in any wandering hedgehogs. I then stated pi-timolo and left it to run overnight!

Results

The following video shows the result of my first attempt at filming hedgehogs:

Please visit the excellent Hedgehog Street website for more information about hedgehogs in the UK and how you can help to support them in your garden.

Updated on 2016-05-26 08:42:12 +0000 | Requested on 2017-06-26 01:43:56 +0000