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| Question about official race courses, google maps and garmin (Read 340 times) |
| view log |
posted: 2/10/2008 at 1:34 AM
modified: 2/10/2008 at 1:35 AM |
| Ok, this is probably a dumb question, but I just plotted the race course for the upcoming ING Georgia Marathon on RA google maps, and it showed the course to be more than 27 miles long. Also, I just ran a 10K today, and plotted the course, and it was 6.33 miles long. Also wth the 10K race, my garmin showed it was about 6.33 miles long too. All I can think of is 1) plotting things on Google maps is inherently inaccurate, and you invariably add a little bit of distance to the actual course distance - although an extra mile seems excessive (maybe I made a mistake), and 2) maybe the reason the Garmin showed a longer course than 6.2 miles was that maybe I didn't 'run the tangents' very well or something? Or is the GPS not perfectly accurate either? |
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| view log Funky Monkey |
posted: 2/10/2008 at 2:28 AM |
Okay, so there are loads of ways to measure a route. All methods have error. Only manual measurement with a measuring device such as a wheel or a bike can be used for course certification, but even these can have error. When a course is certified as being a distance, it is actually certified as being at least that distance. So a certified 5k can actually be 3.2 miles. But most try to be right on to about 1% long.
When you map a course using RA.com or another gmap tool, chances are you do not zoom all the way in under satellite view to get as close to the road as possible. As a result, you may not actually follow the true route, but instead take a lot of the curves wide (or short), which can impact the total distance your gmap program calculates. When you do zoom all the way in, it tends to be pretty good.
GPS devices are as accurate as their satellite lock permits. Each device tries to triangulate (polyangulate?) from among the numerous satellites overhead. Trees, hills, buildings, clouds, powerlines, etc can attenuate their satellite lock. The GPS tracing can also take curves wide or narrow even with a good satellite lock, but in the case of a poor lock, this can be worse.
So no methods is perfect, but running the course with a wheel is likely the best. GPS on a good day and gmap if you are careful can be every bit as good. |
| It's all fun and games until the flying monkeys attack. |
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| view log Grand Illusionist |
posted: 2/11/2008 at 2:50 PM |
| Just for S'n'G's, I plotted an overlay using this cite's tool for a certified 5K course and the mileage came out spot on (to within the 10th). There's a little more disparity with longer and longer distances but over all, the tool here is pretty good. Like Trent pointed out, zooming in closer made a big difference and tracing as close to the actual road is key. |
2008 Goals:
Work out cold fusion
Spinx Runfest Marathon, October 25
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| view log Trample the Weak |
posted: 2/11/2008 at 2:53 PM |
| Quote from Trent on 2/10/2008 at 2:28 AM:
So no methods is perfect, but running the course with a wheel is likely the best. GPS on a good day and gmap if you are careful can be every bit as good.
Out of idle curiosity, how was the Monkey measured?
Yes, for real. Yes, I know you've answered this before. But I'm old and forgetful.
I'll bet the answer involves alcohol, a ruler, and your thumb. |
E-mail: JakeKnight2002@aol.com
"The past is nothing but a series of recollections; it does not own you ... if we are prisoners of the past, we are jailer as well."
~~ Jack Kerley, The Hundredth Man
Unedited Running-Related Song Lyrics
You're a runner
but you're chasing yourself
Feel a hot breath on your shoulder.
Oh, wait. That's just Tanya.
~~ DIO
Less thinking, more running. |
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| view log Funky Monkey |
posted: 2/11/2008 at 3:01 PM |
Monkey measures:
11.2 is a certified course. You run that twice, minus a hair.
11.1 x 2 = 22.2
Add Shell Hill, 1.4 miles. Twice.
1.4 x 2 = 2.8
22.2 + 2.8 = 25
Add Luke Lea, 0.6 miles
25 + 0.6 = 25.6
Add the XC field, 0.3 miles, twice
0.3 x 2 = 0.6
25.6 + 0.6 = Hell. |
| It's all fun and games until the flying monkeys attack. |
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| view log Trample the Weak |
posted: 2/11/2008 at 3:04 PM |
Objection. Non-responsive.
Your honor, please direct the witness to explain how exactly he measured the non-11.2 parts of the course.
"Hair?" That's not very precise.
I was right, wasn't I? You were up late one night with a bottle of plum brandy and a protractor. |
E-mail: JakeKnight2002@aol.com
"The past is nothing but a series of recollections; it does not own you ... if we are prisoners of the past, we are jailer as well."
~~ Jack Kerley, The Hundredth Man
Unedited Running-Related Song Lyrics
You're a runner
but you're chasing yourself
Feel a hot breath on your shoulder.
Oh, wait. That's just Tanya.
~~ DIO
Less thinking, more running. |
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| view log Funky Monkey |
posted: 2/11/2008 at 3:14 PM |
RunningAHEAD.com + GPS + car + somebody once went out on a bike and measured the course.
+ brandy.
+ turtles. I like turtles. |
| It's all fun and games until the flying monkeys attack. |
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| view log Trample the Weak |
posted: 2/11/2008 at 3:17 PM |
I'll bet its 27 miles.
I'm telling everybody I'm an ultramarathoner now. Any idea where I can get a t-shirt? |
E-mail: JakeKnight2002@aol.com
"The past is nothing but a series of recollections; it does not own you ... if we are prisoners of the past, we are jailer as well."
~~ Jack Kerley, The Hundredth Man
Unedited Running-Related Song Lyrics
You're a runner
but you're chasing yourself
Feel a hot breath on your shoulder.
Oh, wait. That's just Tanya.
~~ DIO
Less thinking, more running. |
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| view log Funky Monkey |
posted: 2/11/2008 at 3:27 PM |
It is actually 25.9 miles.
You need some plum brandy. Not another shirt. |
| It's all fun and games until the flying monkeys attack. |
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| view log Trample the Weak |
posted: 2/11/2008 at 3:31 PM |
| Quote from Trent on 2/11/2008 at 3:27 PM: It is actually 25.9 miles.
That better not be true. Or I'll complain to the race director. |
E-mail: JakeKnight2002@aol.com
"The past is nothing but a series of recollections; it does not own you ... if we are prisoners of the past, we are jailer as well."
~~ Jack Kerley, The Hundredth Man
Unedited Running-Related Song Lyrics
You're a runner
but you're chasing yourself
Feel a hot breath on your shoulder.
Oh, wait. That's just Tanya.
~~ DIO
Less thinking, more running. |
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