Topics

1

TopoFusion Pro / DEM gives zero elevation? Can't figure it out.

« on: July 04, 2015, 10:18:24 AM »

What am I doing wrong?

Some tracks can be corrected with DEM but others, or just parts of others will go to zero elevation when using the same feature.  The tracks are a mix of drawn by hand and actual GPS taken from a Garmin 510 unit.

Attached a file that when corrected displays a large chunk of missing elevation if anyone wants to try it and gets different results.

Thanks in advance - Matt

2

TopoFusion Pro / Elevation comparisons between Edge and eTrex

« on: October 03, 2011, 06:07:49 PM »

Went on a ride yesterday with my trusty Garmin Edge 305 and brand new Garmin eTrex 30 to compare the two.  Predicatbly, they roughly recorded the same track over 22 miles.  What I wasn't expecting was the elevation numbers.

When I uploaded to Garmin Connect I got 990 ft (eTrex) and 2427 ft (Edge).  Knowing those numbers never seem to be "correct", I exported to TF and got more confused with 1722 (eTrex) and 4922 (Edge).  I looked here on the forums for awhile and read through the manual, finally found the "Correct elevation using DEM" button and got 1690 ft (eTrex) and 1863 ft (Edge).

So, which is "correct" and why?  Why such different initial numbers from two units?  Playing around with some of my older tracks I see a wide variety of swings from very close to original TF reading to 50% gain and 50% loss using the same process above.

Another anomoly which I have seen before generally when riding in changing weather (I think) is that the start and stop points should have read the same eleveation but instead saw a steady increase in the elevation overall so ended up higher than I started in the exact same spot (disappears after correcting using DEM).  Barometric pressure changes affecting the units?

Thanks for any insight!