Altimeter Grade Graphing ("pain-o-meter")


The altimeter grade is the average grade over roughly 1/10 of a mile, from my altimeter data. This is intended to convey the overall difficulty of the climb, and put the max. grades in a proper context. At this resolution, a 10-foot altitude error (the maximum precision of my altimeter) translates to a 2% grade error.

I don't know the accuracy of this data, but it should give a rough picture of the climbing involved.

The horizontal grid lines are at 10% grade intervals, and the vertical grid lines are at 1 mile intervals.

I linearly interpolated my original altitudes to find a piecewise linear grade before computing the 1/10 mile averages.

Example: Redwood Gulch

I started with my list of distances and altitudes:

Each horizontal line is 100 feet.


Then I linearly interpolated the altitudes:

Each horizontal line is 100 feet.


And took the derivative (slope):

Each horizontal line is 10% grade.


Then I smoothed it using this filter, a gaussian, to get rid of some of the noise in the data. (This is the impulse response, from an instantaneous 50-foot climb.)

Each horizontal line is 10% grade.


And this is the result:

Each horizontal line is 10% grade.


Finally, I subsampled this function at 40 pixels per mile:

Each horizontal line is 10% grade.


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