calibrate.js produces incorrect output

[szulu107]

Describe the bug The calibrate.js file has a draw function for the bottom canvas on the Calibrate page. The function sometimes draws the correct output and sometimes it doesn't.

To Reproduce Steps to reproduce the behavior:

1. Go to 'http://dione.ms.wits.ac.za/index.html'
2. Login
3. Click on 'Calibrate'
4. Click on 'wits_msl'
5. Change value of the select item
6. Scroll down to bottom image
7. See error

Expected behavior The function is supposed to draw a polygon according to the coordinates it receives from the database.

Screenshots Instead of drawing a polygon, it just refreshes the image.