Diane brought along some dresses she has made:
Diane wanted to scan in all her fabric squares that people had drawn and written on at the 2017 Shenzhen Makers Faire:
To do this, she used the Doc-Pi camera rig:
And by closing the glass lid, automaticly kicked off the LEDs and photography process:
Doc-Pi is a Raspberry Pi 2, Raspberry Pi Camera and Display based system. Below is a view of the electronics board and 3D printed stands from behind the RPi:
Once the photo has been taken, a OpenCV based Python script locates the block edge:
this can then be applied to the photo:
Then the internal edges can be excluded:
From the rough block edge outline, you can find each of the four corners (green box):
Next the block image can be cut out, auto-rotated horizontal, resized and saved to a USB flash drive:
A special voltage reference board was used to compare different multimeter's, across four different voltages. The worst meter, was the $7.00 yellow meter, at 0.3%, with the best at 0.05% out. Both are not too bad.