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| Author |
GPS Elevation Data, Waypoints, and Tracks
|
|
| Bob Bailey 2007-09-18, 10:33 pm |
| In theory anyway, elevation can be calculated from GPS data. Surveying
is done this way as I understand it.
Can any of the Garmin devices record a waypoint with calculated
elevation? I have a nuvi 350 and it only seems to know about the topo data.
Can any of the Garmin devices record a track, say, every 20 feet or
whatever that includes calculated elevation data?
I apologize for my ignorance and thank you for any help.
....Bob
| |
| Bob Bailey 2007-09-18, 10:33 pm |
| Bob Bailey wrote:
> In theory anyway, elevation can be calculated from GPS data. Surveying
> is done this way as I understand it.
>
> Can any of the Garmin devices record a waypoint with calculated
> elevation? I have a nuvi 350 and it only seems to know about the topo data.
>
> Can any of the Garmin devices record a track, say, every 20 feet or
> whatever that includes calculated elevation data?
One other point: my nuvi 350 calculates elevation and it can be seen on
the Satellite panel (click the Signal Strength bars on the main menu). I
don't see this data anywhere else in the unit.
| |
| Mark Illingworth 2007-09-18, 10:33 pm |
| "Bob Bailey" < bobat@messagebuilder
sdot.com> wrote in message
news:0aOdnZFFH6qspm3
bnZ2dnUVZ_qqgnZ2d@rc
n.net...
> In theory anyway, elevation can be calculated from GPS data. Surveying is
> done this way as I understand it.
>
> Can any of the Garmin devices record a waypoint with calculated elevation?
> I have a nuvi 350 and it only seems to know about the topo data.
>
> Can any of the Garmin devices record a track, say, every 20 feet or
> whatever that includes calculated elevation data?
>
> I apologize for my ignorance and thank you for any help.
>
> ...Bob
Yes. All the Garmin receivers that I have used record the track with
altitude. In the eMap, GPS V, Street Pilot III and 2610 this is GPS
altitude, ie determined by measurement from GPS satellite signals. I think
this is what you mean by calculated. In the eTrex Vista C and GPSMap 60CSx
the altitude is determined by the built-in barometric altimeter. Most of
them have a setting to determine how often (in time or distance) a track
point is recorded, but I usually just leave it on automatic. The 60CSx can
be set to record onto the microSD data card, so it can hold many days
tracks. The StreetPilots struggle to hold one.
| |
|
|
| Bob Bailey 2007-09-21, 10:33 pm |
| Mark Illingworth wrote:
> "Bob Bailey" < bobat@messagebuilder
sdot.com> wrote in message
> news:0aOdnZFFH6qspm3
bnZ2dnUVZ_qqgnZ2d@rc
n.net...
>
> Yes. All the Garmin receivers that I have used record the track with
> altitude. In the eMap, GPS V, Street Pilot III and 2610 this is GPS
> altitude, ie determined by measurement from GPS satellite signals. I think
> this is what you mean by calculated. In the eTrex Vista C and GPSMap 60CSx
> the altitude is determined by the built-in barometric altimeter. Most of
> them have a setting to determine how often (in time or distance) a track
> point is recorded, but I usually just leave it on automatic. The 60CSx can
> be set to record onto the microSD data card, so it can hold many days
> tracks. The StreetPilots struggle to hold one.
Will an eTrex H or Legend record the track with altitude?
| |
|
| On Sep 21, 3:48 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
> Will an eTrex H or Legend record the track with altitude?
Yes, both of those will do so.
| |
| Bob Bailey 2007-09-22, 10:33 am |
| peter wrote:
> On Sep 21, 3:48 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
>
>
> Yes, both of those will do so.
Ahhhhh, Great! Problem, confusion and dilemma solved.
THANKS!
| |
| Jack Erbes 2007-09-22, 12:33 pm |
| Bob Bailey wrote:
> peter wrote:
>
> Ahhhhh, Great! Problem, confusion and dilemma solved.
>
> THANKS!
And here is a good explanation of how the GPS altitude is calculated and
some discussion of reasonable expectations for the accuracy that you can
expect to get with it.
http://gpsinformation.net/main/altitude.htm
When on the ocean in my area (Maine, USA), I expect to see what my
Garmin refers to as the "0" level as being about 15-40 feet higher than
actual sea level. And if I look at specific track points I can see
wildly varying excursions from that number.
If you are interested in it for marine use, some of the Garmin handhelds
come preloaded with a America's Marinepoint Database and that has many
tide reference points in it. Those are seen as small blue/white icons
and you can select and query those with your cursor to get very good
localized, detailed, and accurate tide information.
Jack
| |
| Bob Bailey 2007-09-23, 10:33 am |
| Jack Erbes wrote:
> Bob Bailey wrote:
>
> And here is a good explanation of how the GPS altitude is calculated and
> some discussion of reasonable expectations for the accuracy that you can
> expect to get with it.
>
> http://gpsinformation.net/main/altitude.htm
>
> When on the ocean in my area (Maine, USA), I expect to see what my
> Garmin refers to as the "0" level as being about 15-40 feet higher than
> actual sea level. And if I look at specific track points I can see
> wildly varying excursions from that number.
>
> If you are interested in it for marine use, some of the Garmin handhelds
> come preloaded with a America's Marinepoint Database and that has many
> tide reference points in it. Those are seen as small blue/white icons
> and you can select and query those with your cursor to get very good
> localized, detailed, and accurate tide information.
Jack, Thanks for your help, and previous help as well.
I bought an eTrex Legend yesterday and it does what I want. Expect to
see a flood of questions on the ng as I play with it.
I looked at the article above and found it useful. Specifically, what I
am doing is tracks of bike rides. I want the elevation data to generate
the vertical profile of the ride. Am I correct in assuming that the
error will be consistent throughout the duration of, say, a two-hour
ride? I'm more interested in the up and down slopes than absolute altitude.
....Bob
| |
| Jack Erbes 2007-09-23, 10:33 pm |
| Bob Bailey wrote:
<snip>
> Jack, Thanks for your help, and previous help as well.
>
> I bought an eTrex Legend yesterday and it does what I want. Expect to
> see a flood of questions on the ng as I play with it.
>
> I looked at the article above and found it useful. Specifically, what
> I am doing is tracks of bike rides. I want the elevation data to
> generate the vertical profile of the ride. Am I correct in assuming
> that the error will be consistent throughout the duration of, say, a
> two-hour ride? I'm more interested in the up and down slopes than
> absolute altitude.
I don't think the error will be consistent, the elevation error will
vary as the EPE varies I'd think. The article mentions that altitude
error is "specified to be" 1.5 times the horizontal error so that gives
you some feel for the variations that might be expected.
But I think the GPS elevations in the profiles can work to give you some
useful info though. It will be interesting to see how it goes for you.
I generally only use track in a plan view over mapping, not in profile.
When I recently looked at the profiles of tracks of four to five hour
runs in a boat (at a constant speed and on smooth seas) I saw a lot of
unexpected changes in elevation and variations of 80 feet or so between
the highest and lowest points.
The boat was on a relatively flat, smooth, surface and the variations in
wave heights could not account for more than plus or minus two feet or
so. The geoid or "0" level appeared to be about 25-40 above sea level
but I couldn't account for all the variations.
I look at the GPS occasionally during those runs and always see a WAAS
fix with 10-12 satellites all of the time. Sometimes the GPS receiver
lays in one spot untouched for one or two hours at a time so I don't
think it relates to me handling it occasionally.
You can filter the trackpoints when you look at profiles and that will
smooth out the variations while preserving the trends. That might be
what you'll want to do.
I've not done similar things with tracks collected over hilly terrain,
not sure what that would show. But I wouldn't be surprised to see the
same kind of variations.
Jack
| |
| Larry G 2007-09-24, 7:33 am |
| On Sep 23, 10:24 pm, Jack Erbes <jac...@midmaine.com> wrote:
> Bob Bailey wrote:
>
> <snip>
>
> I don't think the error will be consistent, the elevation error will
> vary as the EPE varies I'd think. The article mentions that altitude
> error is "specified to be" 1.5 times the horizontal error so that gives
> you some feel for the variations that might be expected.
>
> But I think the GPS elevations in the profiles can work to give you some
> useful info though. It will be interesting to see how it goes for you.
>
> I generally only use track in a plan view over mapping, not in profile.
> When I recently looked at the profiles of tracks of four to five hour
> runs in a boat (at a constant speed and on smooth seas) I saw a lot of
> unexpected changes in elevation and variations of 80 feet or so between
> the highest and lowest points.
>
> The boat was on a relatively flat, smooth, surface and the variations in
> wave heights could not account for more than plus or minus two feet or
> so. The geoid or "0" level appeared to be about 25-40 above sea level
> but I couldn't account for all the variations.
>
> I look at the GPS occasionally during those runs and always see a WAAS
> fix with 10-12 satellites all of the time. Sometimes the GPS receiver
> lays in one spot untouched for one or two hours at a time so I don't
> think it relates to me handling it occasionally.
>
> You can filter the trackpoints when you look at profiles and that will
> smooth out the variations while preserving the trends. That might be
> what you'll want to do.
>
> I've not done similar things with tracks collected over hilly terrain,
> not sure what that would show. But I wouldn't be surprised to see the
> same kind of variations.
>
> Jack
I concur with Jack. I use a 76csx in a canoe on rivers.. and most
folks know that rivers usually change fairly gradually in altitude...
and ..lose altitude as they go downstream.
I see elevation data that is not only at odds with topographic maps
but I also see elevation data that show higher elevations
_downstream_... and not just a couple of feet - sometimes 20 or 30 or
more feet.
Most rivers that can be paddled by canoe lose.. on the order of 10 to
30 feet per mile or less.. rivers can be almost dead flat down where
they go tidal.
so.. when I'm 30 miles downstream and seeing an altitude on the GPS
that shows me to be 20 feet higher than when I was 30 miles upstream..
I know it is wrong...
and.. as Jack points out.. It's not consistently wrong.. it can and
does vary considerably...
... and as Jack says also.. if you leave the unit on but don't pick it
up.. it will not "stabalize" to a specific altitude.. but instead will
continue to vary... even though it is not moved at all...
| |
| Bob Bailey 2007-09-24, 10:33 am |
| Jack Erbes wrote:
> Bob Bailey wrote:
> <snip>
>
> I don't think the error will be consistent, the elevation error will
> vary as the EPE varies I'd think. The article mentions that altitude
> error is "specified to be" 1.5 times the horizontal error so that gives
> you some feel for the variations that might be expected.
>
> But I think the GPS elevations in the profiles can work to give you some
> useful info though. It will be interesting to see how it goes for you.
>
> I generally only use track in a plan view over mapping, not in profile.
> When I recently looked at the profiles of tracks of four to five hour
> runs in a boat (at a constant speed and on smooth seas) I saw a lot of
> unexpected changes in elevation and variations of 80 feet or so between
> the highest and lowest points.
>
> The boat was on a relatively flat, smooth, surface and the variations in
> wave heights could not account for more than plus or minus two feet or
> so. The geoid or "0" level appeared to be about 25-40 above sea level
> but I couldn't account for all the variations.
>
> I look at the GPS occasionally during those runs and always see a WAAS
> fix with 10-12 satellites all of the time. Sometimes the GPS receiver
> lays in one spot untouched for one or two hours at a time so I don't
> think it relates to me handling it occasionally.
>
> You can filter the trackpoints when you look at profiles and that will
> smooth out the variations while preserving the trends. That might be
> what you'll want to do.
>
> I've not done similar things with tracks collected over hilly terrain,
> not sure what that would show. But I wouldn't be surprised to see the
> same kind of variations.
>
Thanks Larry and Jack. I'm a paddler also and one of the things that I
might like to do eventually is record river tracks. Although I typically
paddle stuff with more gradient, like 50+ fpm, so leaving the unit out
is not really an option. Or, is it?
Anyway, Jack mentioned filtering. When I tried that in MapSource I could
not see any pattern to the results. Nor did I see any way to control the
filtering in a meaningful way. Can you help me understand filtering a
little bit better?
btw, I also have ExpertGPS and it does not seem to have a filter tool.
Thanks... Bob
| |
| Bob Bailey 2007-09-24, 10:33 pm |
| Jack Erbes wrote:
>
> You can filter the trackpoints when you look at profiles and that will
> smooth out the variations while preserving the trends. That might be
> what you'll want to do.
>
I asked about filtering in another thread. Maybe you can help me
understand how it works and how to manage it. I tried filtering some
tracks and the result was nonsensical.
tia... BOb
| |
| Larry G 2007-09-24, 10:33 pm |
| On Sep 24, 10:28 am, Bob Bailey <bo...@messagebuildersdot.com> wrote:
> Jack Erbes wrote:
>
>
>
>
>
>
>
>
>
>
> Thanks Larry and Jack. I'm a paddler also and one of the things that I
> might like to do eventually is record river tracks. Although I typically
> paddle stuff with more gradient, like 50+ fpm, so leaving the unit out
> is not really an option. Or, is it?
>
> Anyway, Jack mentioned filtering. When I tried that in MapSource I could
> not see any pattern to the results. Nor did I see any way to control the
> filtering in a meaningful way. Can you help me understand filtering a
> little bit better?
>
> btw, I also have ExpertGPS and it does not seem to have a filter tool.
>
> Thanks... Bob- Hide quoted text -
>
> - Show quoted text -
I'll leave the filtering issue to Jack.
in terms of leaving the unit "out".. not sure what you paddle but I do
open boat and I velcro the unit to my center thwart... with a safety
line. The unit has gotten wet often and takes virbrations without ill
effects... You could also afix it to your life jacket with the glisson
case... it'll stay with the satelittes fine.. only time it did not.. I
was right beside a several-hundred feet vertical wall... and only lost
the signals for a few seconds.
but .. in terms of altitude and trying to set up a gradiant profile
for a section of river... hmmm.. maybe you'll have better luck than
me... on my last trip.. the unit showed an elevation higher on a camp
that the camp the day before which was 25 miles upstream... and I
figured there should have been at least 50 foot of drop...
I don't think this is due to Garmin or the 76csx model but rather..
GPS technology in general. Perhaps others .. can further explain.
| |
| peter 2007-09-24, 10:33 pm |
| On Sep 24, 2:25 pm, Larry G <gross.la...@gmail.com> wrote:
....
> I'll leave the filtering issue to Jack.
> ...
> but .. in terms of altitude and trying to set up a gradiant profile
> for a section of river... hmmm.. maybe you'll have better luck than
> me... on my last trip.. the unit showed an elevation higher on a camp
> that the camp the day before which was 25 miles upstream... and I
> figured there should have been at least 50 foot of drop...
The problem with using a consumer GPS for river gradients is that
they're so small that relatively minor errors can be quite significant
or even larger than the actual elevation changes. Using a measuring
tool with an accuracy of +/- 40' to measure something that only
changes by 30' is going to be an exercise in frustration.
OTOH, Bob mentioned a planned use for bicycle routes in hilly terrain
and there the situation is quite different. For example, earlier
today I went on a ride of about 60 miles at elevations ranging from
30' to over 1200'. There were three significant climbs that were each
over 500' and on these the GPS errors of +/- 40' are a reasonably
small percentage. The tracklog, elevation profile, and cumulative
elevation gain of the ride are shown here:
http://www.everytrail.com/view_trip.php?trip_id=4510
Comparing the elevation profile to my recollection of the ride there's
only one obvious glitch and that is right at the start of the track
where it shows an immediate (and fictitious) drop of almost 200'.
That's because the unit was previously used near my home (at about
500' over MSL) and this ride started a few miles away at an elevation
of just over 300'. When first turned on, the unit initially got a 2D
lock and used the previous elevation value but then got a 3D lock and
corrected the elevation which accounts for the spurious drop shown at
the start of the profile.
As to filtering, I've found that most programs that compute elevation
gains from tracklogs appear to do some filtering but they usually
don't give any indication of what algorithm is in use. When I used
Excel spreadsheets to plot elevation profiles I created my own filter
which ignored any little ups and downs until they exceeded a minimum
threshold value that I generally set to 20'. But once the threshold
was exceeded, then the entire altitude gain was counted. So if the
measurements were 20', 30', 25', 20', 15', 25' then no altitude gain
would be counted for that stretch. But if a subsequent measurement
went up to at least 35' (20' more than the previous minimum, then the
cumulative climb would be incremented with the amount by which the
measurement exceeded the previous minimum. Not perfect, but at least
it prevented little random jumps from adding up significantly during a
ride on basically flat terrain while generally not affecting the
results when riding in terrain with substantial climbs and descents.
| |
| Bob Bailey 2007-09-24, 10:33 pm |
| Larry G wrote:
> On Sep 24, 10:28 am, Bob Bailey <bo...@messagebuildersdot.com> wrote:
>
> I'll leave the filtering issue to Jack.
>
> in terms of leaving the unit "out".. not sure what you paddle but I do
> open boat and I velcro the unit to my center thwart... with a safety
> line. The unit has gotten wet often and takes virbrations without ill
> effects... You could also afix it to your life jacket with the glisson
> case... it'll stay with the satelittes fine.. only time it did not.. I
> was right beside a several-hundred feet vertical wall... and only lost
> the signals for a few seconds.
>
> but .. in terms of altitude and trying to set up a gradiant profile
> for a section of river... hmmm.. maybe you'll have better luck than
> me... on my last trip.. the unit showed an elevation higher on a camp
> that the camp the day before which was 25 miles upstream... and I
> figured there should have been at least 50 foot of drop...
>
> I don't think this is due to Garmin or the 76csx model but rather..
> GPS technology in general. Perhaps others .. can further explain.
>
Thanks, Larry. Helps a lot.
I paddle a kayak so carrying the unit on my pfd would not have the
Legend antenna oriented properly. I'm also down in the water more,
surfing, etc, and tend to get wet a lot.
Having read a little bit more about accuracy and having used the Legend
to record tracks on known territory, I'm convinced that the things I was
thinking of doing won't happen casually with gps unless I edit stuff a lot.
Where do you paddle? I'm near DC, paddle in WV and PA mostly.
....Bob
| |
| Larry G 2007-09-24, 10:33 pm |
| On Sep 24, 7:25 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
> Larry G wrote:
>
>
>
>
>
>
>
>
>
> Thanks, Larry. Helps a lot.
>
> I paddle a kayak so carrying the unit on my pfd would not have the
> Legend antenna oriented properly. I'm also down in the water more,
> surfing, etc, and tend to get wet a lot.
>
> Having read a little bit more about accuracy and having used the Legend
> to record tracks on known territory, I'm convinced that the things I was
> thinking of doing won't happen casually with gps unless I edit stuff a lot.
>
> Where do you paddle? I'm near DC, paddle in WV and PA mostly.
>
> ...Bob- Hide quoted text -
>
> - Show quoted text -
I live near Fredericksburg.. and paddle Mid-Atlantic... and further
afield periodically.
| |
| peter 2007-09-24, 10:33 pm |
| On Sep 24, 4:25 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
> I paddle a kayak so carrying the unit on my pfd would not have the
> Legend antenna oriented properly. I'm also down in the water more,
> surfing, etc, and tend to get wet a lot.
I put my GPS inside an AquaPac transparent plastic case when
kayaking. Although the Legend is supposed to be waterproof by itself,
I think the extra water protection of the case is worth it for a few
reasons: 1) some others have had the seals fail on their Legend model,
2) the battery compartment and electrical connectors aren't spec'd by
Garmin to the same waterproofness as the electronics but water getting
in these could still cause problems, and 3) the IPX-7 spec is for 1 m
submersion in *calm* conditions and a wave breaking on top of the unit
may well be a harsher test. The AquaPac case has it's own sturdy
lanyard which I attach to the boat and I also secure it under a set of
bungy deck cords so it's lying flat on the deck with the antenna up.
Only problem I've encountered is that on hot sunny days the unit
sometimes starts to overheat inside the case. Placing something
(opaque but passing microwave signals) over it to shade it for a short
period cures that issue.
| |
| Jack Erbes 2007-09-24, 10:33 pm |
| Bob Bailey wrote:
> Jack Erbes wrote:
>
> I asked about filtering in another thread. Maybe you can help me
> understand how it works and how to manage it. I tried filtering some
> tracks and the result was nonsensical.
I'm probably wrong about the effect of filtering, I should have said "I
guess you can filter...". I'm the guy the generally only uses and
looks at tracks in a birds eye view and they work fine that way.
They are a mess in the profile view.
I messed with some tracks with MapSource and GPS Utility a little and
realize that does not help. I was thinking there was a way to filter
the more erroneous points out and see the ones that were closer to right
but I see now there there is not really anyway to do that.
Jack
| |
| Bob Bailey 2007-09-25, 3:33 pm |
| peter wrote:
> OTOH, Bob mentioned a planned use for bicycle routes in hilly terrain
> and there the situation is quite different. For example, earlier
> today I went on a ride of about 60 miles at elevations ranging from
> 30' to over 1200'. There were three significant climbs that were each
> over 500' and on these the GPS errors of +/- 40' are a reasonably
> small percentage. The tracklog, elevation profile, and cumulative
> elevation gain of the ride are shown here:
> http://www.everytrail.com/view_trip.php?trip_id=4510
Peter, what did you use to generate the elevation profile? Is there a
way to lay a tracklog directly onto a Google map?
btw, I've pretty much ruled out elevation profiles on the river.
tia... Bob
| |
| Bob Bailey 2007-09-25, 3:33 pm |
| peter wrote:
> On Sep 24, 4:25 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
>
>
> I put my GPS inside an AquaPac transparent plastic case when
> kayaking. Although the Legend is supposed to be waterproof by itself,
> I think the extra water protection of the case is worth it for a few
> reasons: 1) some others have had the seals fail on their Legend model,
> 2) the battery compartment and electrical connectors aren't spec'd by
> Garmin to the same waterproofness as the electronics but water getting
> in these could still cause problems, and 3) the IPX-7 spec is for 1 m
> submersion in *calm* conditions and a wave breaking on top of the unit
> may well be a harsher test. The AquaPac case has it's own sturdy
> lanyard which I attach to the boat and I also secure it under a set of
> bungy deck cords so it's lying flat on the deck with the antenna up.
> Only problem I've encountered is that on hot sunny days the unit
> sometimes starts to overheat inside the case. Placing something
> (opaque but passing microwave signals) over it to shade it for a short
> period cures that issue.
>
Thanks for the tips. It just occurred to me that this would be really
useful in Jan/Feb when I go to FL and paddle flatwater and swamps. I
have an AquaPac for my Honda keys and it works well; with the remote
buttons I can lock/unlock without taking the keys out.
....Bob
| |
| Bob Bailey 2007-09-25, 3:33 pm |
| Larry G wrote:
> On Sep 24, 7:25 pm, Bob Bailey <bo...@messagebuildersdot.com> wrote:
>
> I live near Fredericksburg.. and paddle Mid-Atlantic... and further
> afield periodically.
>
We may have run into each other. Or will. Paddling is still a small
community.
| |
| Bob Bailey 2007-09-25, 3:33 pm |
| Jack Erbes wrote:
> Bob Bailey wrote:
>
> I'm probably wrong about the effect of filtering, I should have said "I
> guess you can filter...". I'm the guy the generally only uses and
> looks at tracks in a birds eye view and they work fine that way.
>
> They are a mess in the profile view.
>
> I messed with some tracks with MapSource and GPS Utility a little and
> realize that does not help. I was thinking there was a way to filter
> the more erroneous points out and see the ones that were closer to right
> but I see now there there is not really anyway to do that.
I agree. So far I see no way short of brute force manual to get a decent
profile.
| |
|
| On Sep 25, 11:39 am, Bob Bailey <bo...@messagebuildersdot.com> wrote:
> peter wrote:
>
> Peter, what did you use to generate the elevation profile? Is there a
> way to lay a tracklog directly onto a Google map?
>
> btw, I've pretty much ruled out elevation profiles on the river.
>
> tia... Bob
That www.everytrail.com website accepts tracklogs in .gpx format,
which is supported by MapSource and quite a few other software
programs. So just upload your tracklog file to the website and you
get it displayed on your choice of google map or USGS topos and also
get the elevation profile. One nice feature of that site is that if
you took any pictures with a digital camera along the way it'll place
those in the correct locations on the tracklog based on synchronizing
the timestamps in the tracklog with the camera time data for each
picture.
BTW, you can also view tracklogs using GoogleEarth, either directly
from MapSource or by converting the file to .kmz format
(www.gpsvisualizer.com is good for format conversions). That lets you
playback a ride, hike, paddle, etc. as if you were flying in a small
plane about 1000' above the ground.
| |
| Bob Bailey 2007-09-25, 10:33 pm |
| peter wrote:
> On Sep 25, 11:39 am, Bob Bailey <bo...@messagebuildersdot.com> wrote:
>
> That www.everytrail.com website accepts tracklogs in .gpx format,
> which is supported by MapSource and quite a few other software
> programs. So just upload your tracklog file to the website and you
> get it displayed on your choice of google map or USGS topos and also
> get the elevation profile. One nice feature of that site is that if
> you took any pictures with a digital camera along the way it'll place
> those in the correct locations on the tracklog based on synchronizing
> the timestamps in the tracklog with the camera time data for each
> picture.
>
> BTW, you can also view tracklogs using GoogleEarth, either directly
> from MapSource or by converting the file to .kmz format
> (www.gpsvisualizer.com is good for format conversions). That lets you
> playback a ride, hike, paddle, etc. as if you were flying in a small
> plane about 1000' above the ground.
>
Thanks, Peter, visualizer is awesome!
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