[Leica] Antenna vs. roof

[Peter Klein]

This is sort of off-topic, but does involve photography. Is the top of 
my roof tower a bit higher than my neighbor's roof, as it appears to be? 
Or does my iPhone 7 camera's distortion or where I stood make the 
picture meaningless? This is significant because I'm thinking of putting 
up a directional antenna for VHF (ham radio), and having a unobstructed 
view of the horizon is very desirable.
<http://gallery.leica-users.org/v/pklein/temp/IMG_1036RoofAntennas-w.jpg.html>

If you know of a reasonably easy way to determine this without expensive 
surveyor's tools, please tell. ("Brother, can you spare a Theodolite?")

Background:  When the roof tower was installed, the house on the left 
was a one-story rambler. Now it's a McMansion.

--Peter