What are some methods to determine line of sight between ...

What are some methods to determine line of sight between transmission points?

Street Maps: One method is to utilize “street maps”. Street maps are easy to use but provide limited information about RF planning. One needs to determine the location of each site, draw a line between the two locations and measure the distance with a scale.
Topographic Maps: Topographic maps provide information derived from different datum. It also helps provide magnetic offset from the true north. The contour lines provide details about terrain. In general, topographic maps provide a more accurate scale.
Aeronautical Charts: These charts (“sectionals”) are especially useful for locating tall buildings and towers. Furthermore, it details airspace around airports in an accurate fashion. The data is updated frequently. It is important to account for the magnetic offset (subtract for east, add for west).
Web Base Maps: (e.g. Google Maps) Some web based maps may allow for entry of GPS coordinates for the location in question. Additionally, some web based maps provide active GPS coordinates of the location in question.
Path Planning Software: Path planning software often uses a satellite based terrain database. Some popular path planning software programs are EDX, Micropath and Pathloss. The price of these planning software programs range from hundreds to thousands of dollars.