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I am trying to calculate % Grade from GPS points. I am using the basic equation of

(Rise/Run)×100

The problem is I am getting spikes in my GPS data (example 1 meter rise for 3 meter run), I am guessing because of the fluctuation of the Vertical Accuracy of the GPS.

Has anyone dealt with this scenario or know of a way of weeding out the anomalies?

KBurnell
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    Yes I have had that issue. Also, very unlikely, but is the precision of the Z info an integer rather than a decimal? If it is an integer value then your values will be in blocks of one meter, rather than centimeters or millimeters – Ryan Garnett Jul 26 '13 at 12:17
  • @KBurnell, how many points are we talking here? Are these straight line analyses? – Clickinaway Jul 26 '13 at 13:10
  • @RyanGarnett No it is 6 point decimal precision. – KBurnell Jul 26 '13 at 13:19
  • @Clickinaway For context it is an application that runs on a mobile device that is gathering lat,lon,and alt (among other values) every 3 seconds . – KBurnell Jul 26 '13 at 13:21
  • FYI: Question also posted in math.stackexchange: http://math.stackexchange.com/questions/452175/calculating-grade-from-latitude-and-longitude – KBurnell Jul 26 '13 at 13:22
  • Seems like the data from the accelerometer could also be helpful in weeding out spikes. – Kirk Kuykendall Jul 26 '13 at 13:24
  • http://gis.stackexchange.com/questions/17014/how-to-get-an-elevation-profile-for-a-gps-track would that be of any help? – Clickinaway Jul 26 '13 at 13:27

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