For VHF, UHF and uWAVE point to point links, it is necessary to know the exact profile between the two locations.
The exact profile will determine whether there is Fresnel zone clearance and determine free space loss and any obstruction losses. Previously this was done on 1:50K topograpic maps, but nowadays this can be done using digital topographic information.
Splat! is a powerful Open Source program that can be used to plan these point to point links as well as other propagation parameters.