Run Number 57: GPS vs. Ground Truth

I am…the Botendaddy.

Many of you do not know this, but Botendaddy has a B.S. in Computer Science and is halfway to a Masters of Information Science in Big Data. I may shift focus to GIS.

At any rate, I use the ‘Map My Run’ app for tracking my runs while enroute.

There is often significant variance between ‘ground truth’ and the GPS.

But, we have to depend upon whomsoever measured the mile post and whatever system they used: bicycle, unicyclish-roller-thingy, car, etc..

So I went back over my run times this year. Everywhere I showed more or less mileage than the stated distance of the particular time official run, I redacted the distance to whatever the official race distance was. i.e., I had 5.27 on my GPS for a five mile run. So I dropped the mileage to 5.00.

But, I add a transition sentence.

GIS is an interesting science. It depends upon geometric/trigonometric triangulation of location against time. A series of GPS satellites sends out pings to check your location at certain times.

GPS_satellite_constellation

GPS Satellite Orbit Constellation

 

National Oceanic and Atmospheric Administration

But, it has a margin of error, say 10 meters. So if you are running slowly you may get two pings within ten meters and the satellite does not really know where you are so it has to guess.

Slight lateral movements or turns could affect the calculated distance as well. If you are running in a valley, the multi-path signal problem occurs as the ping bounces off of some terrain feature or building until it finds you.

But, it was my third fastest mile, third fastest two mile, third fastest three mile and third fastest 5k of the year.

The problem is that I lost about a third of a mile due to my normalizing of the distances with the stated race course mileage, so now I need to run 6.92 miles before the end of the year. That’s OK, I’ll make it.

I was exhilarated after the run, but I made one mistake. I was not aware of my surroundings. I stopped to record my run on my MapMyRun®™© App. It was the librarian girl from a few weeks ago.

‘Botendaddy. I knew you would be back, but I never imagined you could be so sexy, you big, fat, sweaty, hairy disgusting ape. You, vile, rotting, hulking, super-hot Frankenstein. I didn’t know a fat, hideous, repulsive, monster could run so fast.’

The gorgeous raven-haired librarian was wearing a skin-tight spandex running outfit on her perfect body.

‘Thanks for the complements!’ I said, backing away.

‘I must ask you, do you wish to make love to me, right now, in this parking lot in front of all these people?’

‘Look! A flock of geese!’ I shouted. She turned to look and I made a run for my aged, massive dirt bike. She ran after me for a while, but she tripped in the gravel, making a terrible spectacle of herself, reaching hopelessly towards me in deep yearning.

‘Botendaddy! Come back! I need you!’

I kept pedaling. I was safe for now, but there was hell behind me, the spandex-clad, zombie apocalypse.

Peace be the Botendaddy

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About Botendaddy

Three times voted extreme sexiest man alive...by acclamation. I run because I must...I must!
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