Video summary

Using Google Earth to find line of sight for fixed point wireless Internet

Main summary

Key takeaways

Educational

Main ideas / concepts covered

  • Purpose: Use Google Earth Pro to determine whether two fixed points (e.g., rooftop-to-rooftop) have a clear line of sight, which is a key requirement for fixed point wireless Internet.
  • Core workflow:
    1. Place markers (“placemarks”) for the transmitter/receiver locations with appropriate altitudes.
    2. Use a View Shed quick check to see what’s theoretically visible within a rough radius.
    3. For more accurate analysis, draw a line and convert/export it so you can inspect altitude and geometry along the path.
    4. Visually “walk” along the line to identify obstructions (trees, buildings, hospitals, etc.).
    5. Iterate by adjusting point heights (and/or choosing different relay locations) until the path is unobstructed.
  • Important caveat: Even if line of sight exists today, it can change over time due to new construction (they note buildings potentially affecting future visibility).

Method / step-by-step instructions (detailed)

A) Prepare tools and resources

  • Have a simple note-taking method:
    • Bring a pen and paper to record multiple candidate locations and points of interest.
  • Install software:
    • Download and install Google Earth Pro (desktop app, not the web version).
    • Have a code/text editor ready for later editing of exported KML/KMZ files:
      • On mac, they mention using Brackets (they also refer to Notepad++ on PC).
  • Hardware compatibility concern:
    • Older laptops may not run Google Earth Pro reliably.

B) Start a clean Google Earth project and find the target area

  • Open Google Earth Pro and start from a blank slate for the trainee.
  • Use the search bar to navigate to the working area (they use Ann Arbor as an example).
  • Get comfortable with navigation:
    • Pan: click-and-drag / mouse gestures / trackpad equivalent
    • Rotate: change perspective
    • If the view gets skewed, use search or reset the view

C) Create placemarks for candidate rooftops/relay points

  • Use the Placemark tool (pin icon).
  • Place pins at meaningful locations on structures (they recommend typically toward building edges/rooftop areas).
  • Determine and enter heights:
    • Initially, placemark position is mainly latitude/longitude, with altitude configurable.
    • For quick work, set altitude relative to ground (they demonstrate values around 40 meters, later adjusting by small amounts like +2 meters to clear edges).
  • Use UI hints:
    • Hovering can show elevation (e.g., feet/meters) to help estimate altitude.
  • Editing placemark details:
    • Right-click placemark → Properties / Get Info (UI differs by Mac vs PC)
    • Adjust:
      • Altitude
      • Style/name
      • Coordinates if needed

D) Quick visibility check using “Show View Shed”

  • Right-click a placemark → Show View Shed
  • What it does:
    • Calculates an approximate visibility area from that point.
    • Uses colors to indicate potential visibility (e.g., green for theoretically visible regions).
  • Limitation:
    • View Shed is not very precise at close detail due to building simplification/visual artifacts.

E) Record candidate locations

  • While exploring, drop additional placemarks for candidate sites (e.g., parks, hotels, hospitals).
  • Use placemarks as a “map notebook” when pen-and-paper alone isn’t enough.
  • Example candidate approach:
    • Look for high areas and potential relay spots (parks/fields on hills, tall structures).
    • Write down location descriptors for later verification.

F) Draw a line to test line-of-sight more precisely

  • Use Show Ruler (top bar option) to draw a line between two points.
  • Extend and place the line in 3D:
    • In altitude/path options:
      • Use relative to ground
      • Use extend path to ground
      • Set altitude/path so the line represents the actual elevated geometry
  • Save/export the path:
    • Right-click the line → Save Place
    • Convert from KMZ to KML so it can be edited in a text/code editor

G) Edit KML coordinates to ensure accuracy

  • Open the exported KML in a text editor (Brackets or a similar editor).
  • Coordinate-editing approach:
    • Find coordinates tags in the relevant section.
    • Extract coordinate sets (lat/long and altitude components).
    • Replace/paste coordinates so the line connects:
      • The chosen relay point / hill placemark
      • The chosen destination (e.g., the 777 building)
  • Troubleshooting tips:
    • Copy/paste can introduce errors (e.g., extra minus signs - or formatting issues).
    • Even a small coordinate mistake can put points thousands of feet off.
    • If something goes wrong, re-search the city to re-center and re-check the line.

H) Inspect the line visually for obstructions

  • In Google Earth, display the line (often in red, with shadow/height overlay).
  • Visually “walk through” the line:
    • Identify intersections with obstructions:
      • Trees near endpoints or along the line
      • Buildings (they demonstrate a failing line going through a hospital)
  • Determine if a “gap” might exist:
    • They mention possible narrow clearings but treat these cautiously.
  • Iterate:
    • Try alternative “test lines” from different start/end points.
    • Adjust the model by changing assumed tower height (e.g., 2 meters to 5 meters) and repeat the line check.

Outcome / lessons emphasized

  • Accuracy requires iteration: the workflow is “quick but inefficient,” relying on repeated manual checks.
  • You’re validating physical geometry, not just map distance:
    • Model altitude and verify obstructions.
  • Environmental change matters: future construction can break current line-of-sight.

Speakers / sources featured

  • Dr Ron Suarez (broadband institute; host/guide)
  • Caleb (volunteer; demonstrates Google Earth Pro steps)
  • Nikki (community broadband manager; the learner during the walkthrough)

Original video