*It depends on what website you use. My understanding is that each interpolates the same topo data base in its own way. Also, my impression is that each website keeps tuning their algorithms in the hope of greater accuracy. What's not clear is whether any of these sites get access to side information or secondary databases * * * *My own experience is with the Garmin 705 (which has a barometric altimeter) and a VDO MC1.0+ which also has a barometric altimeter but no GPS. I've found that the two tend to report results within about 10% of each other. The VDO which has doesn't have GPS, tends to do more averaging of the barometer readings. * * * *As for websites, I've been using bikeroutetoaster.com and ridewithgps.com. My experience was that a bikeroutetoaster often underestimated the vertical feet in a route by 10-20%. On the other hand, ridewithgps tended to be closer, and occasionally overestimate a little. It seems possible to me that ridewithgps may well have added a correction factor to account for small ups and downs? * * * *In any case, both have been much better than my experiences with mapmyride. However, I stopped using mapmyride 2 years ago, and it is very possible they have changed their algorithms in the meantime. * ...Roy
On Mon, Feb 15, 2010 at 4:10 PM, Eric Norris <campyonly...@me.com> wrote: > Can't compare web to GPS, but I've found over the years that both calculate > more climbing than is shown by an altimeter watch or bike computer. The > altimeter typically shows about 30% less altitude gain, probably because the > mapped versions add up every little up while most altimeters ignore small > gains. > — Eric Norris > www.campyonly.com > www.wheelsnorth.com > [image: Blog] <http://campyonlyguy.blogspot.com>[image: > Flickr]<http://www.flickr.com/photos/35176...@n03>[image: > Web] <http://www.campyonly.com>[image: Web] > <http://www.wheelsnorth.org>[image: > Web] <http://www.groovyboy.org>[image: Email] <campyonly...@me.com> > > > On Feb 15, 2010, at 12:59 PM, doug peterson <dougpn...@cox.net> wrote: > > In mapping out routes, I've noticed big differences in both distance > and elevation gain between GPS and plotting the same route on web > based mapping services. Distances can be off by 5%-10% and elevation > by double. The web based systems are always higher than GPS. Has > anyone else encountered this? It's entirely possible I'm doing > something wrong on the web based systems. > > dougP > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bu...@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bu...@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com<rbw-owners-bunch%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. > -- Roy D. Yates Professor, E&CE Associate Director, WINLAB http://www.winlab.rutgers.edu/~ryates -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
