Last winter, I tossed my household’s collection of worn-out holiday lights and forgot about them — until last weekend when I went to hang them up for this season. I found myself facing that age-old question: how many strands of Christmas lights to buy.

It turns out that this is a great task for a drone.

Allowing humans to remain on the ground instead of ascending into dangerous situations is one of the great promises of drones in commercial applications. Precarious spots include wind turbines, scaffolding, and, one of the most dangerous spots for the average citizen, on top of a ladder. With two family members recently suffering serious injuries after falling from ladders, I welcome an opportunity to spend less time on the ol’ tipsy metal triangle.

To figure out how many strands of lights to buy, I needed to measure the part of my roofline that I wanted to light up. I could do this from the ground and estimate, but I like to be more precise than that. For the sake of you, my dear reader, I decide to use both a drone and the old-fashioned method and compare.


Method Ladder + Tape Measure

Phantom 3 Pro + Software

Steps required Setup ladder, start to measure, throw bad tape measure off roof and get another one, finish measuring, put away ladder Setup drone, fly the operation, upload pictures, put away drone
Hands-on time 14 mins 17 mins
Measurement 116 ft 115.43 ft

With a sunny day and a low-pitched, single-story roof, it was actually pretty easy, and not too dangerous, to get up on the roof and measure the segments, adding the total in my head as I go. The most frustrating part was when the tape measure jammed and refused to roll back up. I ended up spending a total of six minutes fighting with it before eventually throwing it off the roof and going to find another one. Not counting those wasted six minutes, it took me 14 minutes to measure 116 feet of roofline.

For the drone method, I used Skyward to check for any temporary flight restrictions over my house (there were none) and DroneDeploy to plot the area and fly the mission.

The flight itself took all of one minute and nine seconds, capturing 14 images. Next, I upload the photos. Once my map was ready, I simply selected the measure tool and drew a multi-segmented line that followed the roofline. My measurement was ready as soon as I finished drawing. 115.43 feet the software tells me. Not counting the wait time, I spent about 17 minutes on this method.

The results between the two methods are remarkably close. I can tell you which one I feel more confident in—it’s the one with the decimal point. It also happens to be the method that keeps my feet firmly on the ground. Since my favorite lights come in lengths of 25 feet, I bought six strands of lights (I always buy one for backup).

Before I hung the lights, I needed to make another important measurement in order to figure out the best place to connect the lights in order to limit the visible wires. With only one available outlet, my choices are limited. I wasn’t around in the 1950s when my home was built, but I imagine the discussion about electricity went something like this:

Electrician: “The service drop will attach to the roof here.”
Builder: “Then it connects to that hard to reach corner in the basement?”
Electrician: “Just how everyone likes it. Do I need to wire any outlets on the outside?”
Builder: “On the outside? Of the house?”
Electrician: “Yeah haha, I guess not. Just kidding around. Who needs that?”

Fortunately for me, a previous homeowner at least extended an outlet to be accessible from the outside. However, it is located right under some windows at the front of the house. Because I don’t want an extension cord dangling in front of our windows, I needed to do some more measuring in order to plan the connection point.

In my manual measurement of the total roofline, I only kept a running total. So in order to figure it out this way, I’d have had to get up on the roof and remeasure. That ladder is cold and heavy and I had a better idea. With the orthomosaic data from DroneDeploy already at hand this was as simple as a few clicks. Treating the measuring tool as though it were a strand of lights proved to be very effective. I found the ideal point at which to connect the lights to the extension cord in no time.  

You’ve probably heard the old idiom, “Measure twice, cut once.” In my case, this has been, “Fly once, measure thrice.” Come spring, I plan on using this same data set to measure the square footage of my lawn so I can buy the precise amount of products I’ll need.

2 responses to “How Many Holiday Lights Do I Need? Use a Drone!

  1. Jonathan, this is terrific! Very well written up article and I sure agree with you – much better by drone! Way to go!

  2. Haha nice, I will have to keep this method in mind next year before buying Christmas Lights. Much safer to use the drone for sure. Thanks for the write up!

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