Remote Height Measurement using DISTO Height Tracking

(Skip the story and go to the step-by-step Height Tracking instructions)

Overhead wires: The enemy of hot air balloonists, kite flyers, and -- as was the case the September morning I rolled up to the intersection above -- flatbed truck drivers everywhere.

As the police arrived to manage traffic (and, no doubt, issue an expensive ticket to the driver) and the city workers arrived to extricate the fork lift from the traffic lights, I glanced over at the DISTO D810 Touch laying in my passenger seat.

It occurred to me that it would have been so easy for the driver, or the city for that matter, to use a E7500i or a D810 Touch to measure the clearance between the road and the traffic lights to avoid this kind of thing and, if they had, I wouldn't be late for work.

I thought "I should take a picture and do a blog post on how to do that", so I grabbed my phone and took some pictures ("See, Boss, I wasn't late. I was working from the road.").  Then I forgot about it for four months, which is how I ended up back at that intersection today just as a snowstorm was blowing out of town.

Less comfortable for me, sure, but there are a lot of jobs where working inside when the weather turns isn't an option.  The cold and blowing snow didn't bother the DISTO, which has an IP54 rating and an operating temperature that bottoms out at 14° (it can be stored at -25°. Apparently, the LCD screen needs to be 14° to function properly). 

It took me less than a minute to use the Height Tracking function to determine the height of the traffic lights, and I did it from the safety of the side of the road. No police detail or helper needed. The camera picked up some glare on the screen, so the video below doesn't do the touch screen resolution justice. But, to show how fast you can get this type of measurement, without playing palying in traffic or freezing any longer than necessary, this video does the job:



The other way to do it...

Cautious truck drivers often use a big pole, called a measuring pole, or, more colloquially, a "height stick" to make sure they can get under wires or a low bridge. We even saw a couple of guys from a fiber optic company using this Flintstone technology to measure wire height near our office. 




For the record, the height that the fiber optics guys were trying to hit was 27' 3" 31/32.

Imagine if the hapless driver who snagged that light with the forklift wanted to use a height stick to see if he could clear that traffic light. This is a busy intersection in the middle of Newport RI. At a minimum, he would have needed a police detail to stop traffic. Not that we want to take OT away from the boys in blue, but the reality is that the DISTO offers solutions that save time and money.

How-To Use Height Tracking

So here is how I took that measurement from the side of the road, with traffic whizzing by, step-by-step. The images below are captured directly from the D810 in the field:

1. Select Height Tracking Mode.    
2. Shoot the reference point on the ground beneath the wires. To be accurate you need to hit a spot that is directly below your target. I used the hash marks in the intersection right below the light. Close enough for my purposes. (2x Zoom)   

3. With the reference set, hit the ON/DIST button again and tilt up. This is where the pointfinder comes into play:  It was windy so the traffic light was moving around. In the image you can see that the crosshair isn't hitting the stabilizing bracket. It was when I first lined it up, but then the wind blew when I took the measurement.

With height tracking you don't have to hit a solid object to get a measurement. The DISTO gets the height measurement based on the spot in the crosshair, in relation to the reference point below. (4x Zoom)

4. Once you have your measurement hold down the blue camera button on the keypad to save the dimensions and the picture that goes with it. This is great for documenting exactly what you measured once you're back in the office.

(All of the screen captures above were captured this way.)


Keeping it Steady

I used a tripod and a Fine Tune Adaptor to get maximum accuracy.

A driver might not need that level of accuracy. In fact, a driver could pull to the side of the road and take a height tracking measurement out the window without even getting out of the truck. Try that with a 30ft pole.

(Of course, if a rough freehand measurement returns a height that is too close for comfort, you would want to get out, set up a tripod, make sure your reference point is below your target, and take the time to do it right.)

In the DISTO screen captures I measured the distance to the lowest light, which was ~15ft. When we shot the video, I measured the height of the nearest light, which is a foot higher than the lowest one in the middle, which is the kind of thing the DOT probably needs to know and, if you are a flatbed truck driver with a big forklift on your trailer, the kind of thing you definitely want to know.