Tuesday, July 29, 2014

Accumulated climb and descent: influence of the data quality

Knowing the problematic that exist with the reliability of the height data recorded in plenty of track routes, IBPindex has launched the “Detector & corrector of profile unevenness” algorithm. 

 A brand new automatic tool for the analysis of the track data of which you probably are already aware if you had the chance to follow our previous communications.

The system analyses the tracks identifying the errors, counting them and evaluation the scale of the deviation. From this moment onwards the tool takes over and corrects the track according to the characteristics and number of the detected mistakes.

There are eight possible degrees of correction:

  • From “0” where there’s no correction available, only optimization
  • To “7” maximum correction applicable

With the data already corrected we classify the track reliability degree according to the following scale:

“A” = Very good
“B” = Good 
“C” = Acceptable
“D” = Bad
“E” = Very bad 

You can check this information in the items 

  • Reliability of the original trail    
  • Level of correction applied to the trail 

You can still see and compare the data without correction following the link “See original analysis (without corrections)”

Now we show some examples that will help you to understand the issue with the recorded height data, on the following pictures you can see  you can see different profiles of the same route:

-  One recorded with a standard / normal GPS device (profile “1”) 
-  Another one with a Smartphone (profile “2”)
The same two profiles but substituting for each point the original height with the information of a DEM (Digital Elevation Model) (profiles “1.1” and “2.1”
-  and one generated by IBPindex applying the “unevenness corrector” (profile  “3”)

First, we would like to draw your attention to the saw tooth profiles present both in the Smartphone recorded track (“profile 2”) as in all profiles obtained by using a digital elevation model (DEM) (profiles “1.1” and “2.1”). Please note that the causes for those saw teeth are different for each of the profiles. 

Comparing the profiles 1.1 and 2.1, we also observe that the one recorded with a Smartphone still accumulates more than 100m of error. This is because the track the number of registered points is bigger.

As always, we look forward to your comments to keep improving our website.