Numbers not adding up...

Marko B's Avatar

Marko B

05 Mar, 2019 06:38 AM

Hello,

I have a 3 Day Backpacking Trip coming up so I was using Caltopo to figure out my elevation gain. When I enter the entire route into the map, it tells me the elevation gain is 5,125ft. However, I wanted to go a step further and see what my elevation gain was for each of the three days specifically. When I entered those in and added them up, I got 6,166. I'm at a loss as to why there's a 1,000ft discrepancy for two numbers that should be the same. Here are the aforementioned routes: https://caltopo.com/m/PNQ1

Thank you,
Marko

  1. Support Staff 1 Posted by matt on 05 Mar, 2019 04:40 PM

    matt's Avatar

    The profile is based on about 300 points, so its accuracy will vary by the size of the line (the profile dialog shows the sampling interval, ie 1 elevation point every X feet). With a pro subscription you can change the sampling interval on the full-page profile dialog, but the bottom line is that generating a precise elevation profile is a tricky subject - if you make the sampling interval too small, there's too much up/down noise from the track not being perfect and essentially making it look to the computer like you're weaving back and forth.

    30+ miles is pretty long for a single line, I would go with the 6k number and you probably don't need to resample the individual lines to a smaller interval.

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