The Visual-Pi-ser a low cost classroom visualiser

In may last post I described my idea for a low cost visualiser based on the Raspberry Pi kit I was sent as part of the Element 14 Raspberry Pi Educators Road Test. I promised i would add more detail so here it is.

The box for the kit is used as a stand to hold the RPi case. The case in the kit has a mounting point for the camera and the arrangement holds the camera steady over the items to be shown. The main issue for this set up using the box is that the camera has a relatively large minimum focal distance so items at the range as out of focus until the camera is modified.

To modify the camera is a fixed focus unit and the lens is held in place with blobs of glue that can be removed with a craft knife to free up the lens (N.B. the lens can be sensitive to static and can be easily damaged so this needs to be done with care).

This modification allows the lens to be rotated and the items brought into focus. It also has the added advantage of slightly magnifying the subject.

The size of the box supplied is ideal for small physical computing projects but a larger box would give a larger field of view for bigger projects. The camera itself is controlled by using the Raspivid command:

raspivid -t 300000 -rot 90

This rotates the video by 90 degrees (as the camera mount is at 90 degrees to the box) and runs the video for 30000 miliseconds (30 seconds). If a longer or shorter time period is required then the number of milisecond can be changed. If you want to terminate the video session you can do so by using ctrl+c

I have created a guide on how to crate you own Visual-Pi-ser on github.