Hello everyone,

I have 2 molecular tunnels inside one protein corresponding to two starting points, created by the CAVER plugin. The two tunnels join to form one common tunnel. 

I want to measure

1) The distance between the two starting points of the tunnels

2) The distance from each starting point to the junction

If I follow wizard --> measurements --> distance it asks for atoms to click on, but as the tunnels are empty space when I click on the starting points of the tunnels nothing is recognized. 
What would be the most accurate way of measuring the above two distances?

Thank you

Sajeewa Dewage