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post #16 of (permalink) Old 11-30-2011, 07:48 PM Thread Starter
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I'm really wondering about the accuracy now of Google Earth since I just uploaded my data from a Lynn Peak trip the other weekend and if I move my mouse around the area that would appear to be the peak, the highest I can get is 700m. The book says that Lynn Peak is 920 meters. I know that my GPS read that on the peak becuase I remember looking at it when I reached the top. So now I wonder if the elevation readings on Google Earth are off or the maps themselves are off - if I move my cursor in Goodle Earth to the right some (which is way outside the expected accuracy range of a few meters - I mean (like 100-300 off), I get elevations around the 900m range.

Near the supposed top:




Zoomed out:

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post #17 of (permalink) Old 11-30-2011, 07:51 PM Thread Starter
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I'm really wondering about the accuracy now of Google Earth since I just uploaded my data from a Lynn Peak trip the other weekend and if I move my mouse around the area that would appear to be the peak, the highest I can get is 700m. The book says that Lynn Peak is 920 meters. I know that my GPS read that on the peak becuase I remember looking at it when I reached the top. So now I wonder if the elevation readings on Google Earth are off or the maps themselves are off - if I move my cursor in Goodle Earth to the right some (which is way outside the expected accuracy range of a few meters - I mean (like 100-300 off), I get elevations around the 900m range. So I'm guessing that if I were to follow the same process on the $150 Topo maps, I would get better results?

Near the supposed top:




Zoomed out:


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post #18 of (permalink) Old 11-30-2011, 07:52 PM
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Quote:
quote:Originally posted by ubishops

I'm really wondering about the accuracy now of Google Earth since I just uploaded my data from a Lynn Peak trip the other weekend and if I move my mouse around the area that would appear to be the peak, the highest I can get is 700m. The book says that Lynn Peak is 920 meters. I know that my GPS read that on the peak becuase I remember looking at it when I reached the top. So now I wonder if the elevation readings on Google Earth are off or the maps themselves are off - if I move my cursor in Goodle Earth to the right some (which is way outside the expected accuracy range of a few meters - I mean (like 100-300 off), I get elevations around the 900m range.

Near the supposed top:




Zoomed out:


I'm not sure if this would matter but check your datum setting on the GPS unit. What is it currently set to?

FWIW, I have found the Google Maps to be extremely accurate. Whether I take a waypoint from my GPS unit or from an external source (such as Bivouac,) it is almost always placed almost exactly in the right spot on the map.

On the other hand, there are times when my GPS is clearly wrong; especially in dense tree cover or with low batteries.
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post #19 of (permalink) Old 11-30-2011, 08:02 PM Thread Starter
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Quote:
quote:Originally posted by Steventy

Quote:
quote:[i]


I'm not sure if this would matter but check your datum setting on the GPS unit. What is it currently set to?
WGS 84 - not sure if that gets us any closer to the answer but worth checking. I thought it might have something to do with the fact that I don't have any of the purchased maps on my GPS unit but I don't think that should make a difference - GPS coordinates are coordinates. They should line up with what is in Google Earth, and in the city for the most part they do (tested it this morning and as I was going over the Second Narrows bridge, the track followed it perfectly, even the right lane (if I compare that to what I'm getting in the back country, I'd be in the water lol
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post #20 of (permalink) Old 11-30-2011, 08:04 PM
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Perhaps it depends on what you consider to be the "summit".

I believe most books and popular belief is that Lynn Peak is the rock bluff clearing with the views. In Google Earth, that elevation is 920m or thereabouts. That is not the actual "Lynn Peak" though, which is further up and is a treed summit with no views. Elevation there is in the 990's.

Here is my GPS track of this in GE - the dip into the clear spot is the bluff viewpoint, and the end is the peak proper.

-Ryan

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post #21 of (permalink) Old 11-30-2011, 08:07 PM
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Quote:
quote:Originally posted by ubishops

Quote:
quote:Originally posted by Steventy

Quote:
quote:[i]


I'm not sure if this would matter but check your datum setting on the GPS unit. What is it currently set to?
WGS 84 - not sure if that gets us any closer to the answer but worth checking. I thought it might have something to do with the fact that I don't have any of the purchased maps on my GPS unit but I don't think that should make a difference - GPS coordinates are coordinates. They should line up with what is in Google Earth, and in the city for the most part they do (tested it this morning and as I was going over the Second Narrows bridge, the track followed it perfectly, even the right lane (if I compare that to what I'm getting in the back country, I'd be in the water lol
That should work. It isn't a problem with the datum.

Do any GPS experts know if this would matter in the first place? If you change the datum, does it change the way points are recorded, or does it only change the way the GPS unit would place points on a map?
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post #22 of (permalink) Old 11-30-2011, 08:25 PM Thread Starter
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Quote:
quote:Originally posted by Ryan.in.yaletown


Perhaps it depends on what you consider to be the "summit".

I believe most books and popular belief is that Lynn Peak is the rock bluff clearing with the views. In Google Earth, that elevation is 920m or thereabouts. That is not the actual "Lynn Peak" though, which is further up and is a treed summit with no views. Elevation there is in the 990's.

Here is my GPS track of this in GE - the dip into the clear spot is the bluff viewpoint, and the end is the peak proper.

-Ryan

That's a good point - that would explain the Lynn Peak one but the Outhouse Juction and Black Tusk Junction in Garibaldi Lake is a mystery But no worries - won't be long before I'm there again so I'll re-track it and compare. Thanks for the tips Below you can see that the distance between the two points are accurate but being in the Lake is weird. I also marked the Helm Junction which seems to be more accurate.

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post #23 of (permalink) Old 11-30-2011, 09:02 PM Thread Starter
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I'm finding that the new bird's eye view through Bing (http://www.bing.com/maps/) has a much more detailed satellite view than Google Earth. Compare the two photos below:

Google Earth:




Bing: (Bird's Eye View zoomed)




Seems to apply to the backcountry too. If you compare Opal cone in Google Earth and then in Bing with Bird's Eye View, a world of difference (You can't even see half of Opal Cone/Rampart Ponds in Google Earh because it's covered over but can make out a lot of detail in Bing). I think the images from Bing are via Microsoft (MDA Geospatial Service Inc - NAVTEQ).
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post #24 of (permalink) Old 11-30-2011, 09:10 PM
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As for the comment about the CD..
Well the eTrex Vista H I purchased for my GF didn't come with the CD. And I had to use work around to upload mapsource onto her PC.

As for the track off on google earth well I'm not sure what to say ...
But my mapsource to google earth works like a charm...

As you can see I uploaded the same area into google.
mine


Yours



Quote:
quote:Originally posted by ubishops

Quote:
quote:Originally posted by Ryan.in.yaletown


Perhaps it depends on what you consider to be the "summit".

I believe most books and popular belief is that Lynn Peak is the rock bluff clearing with the views. In Google Earth, that elevation is 920m or thereabouts. That is not the actual "Lynn Peak" though, which is further up and is a treed summit with no views. Elevation there is in the 990's.

Here is my GPS track of this in GE - the dip into the clear spot is the bluff viewpoint, and the end is the peak proper.

-Ryan

That's a good point - that would explain the Lynn Peak one but the Outhouse Juction and Black Tusk Junction in Garibaldi Lake is a mystery But no worries - won't be long before I'm there again so I'll re-track it and compare. Thanks for the tips Below you can see that the distance between the two points are accurate but being in the Lake is weird. I also marked the Helm Junction which seems to be more accurate.

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post #25 of (permalink) Old 11-30-2011, 09:13 PM
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Ditto to what Ryan & Seventy said: my tracks always line up properly on Google Earth, except for when the GPS is obviously having trouble (occasionally in deep valleys, indoors etc) in which case you can easily spot the errors as the track randomly takes large jumps. Here's my Lynn Peak track for comparison:



You can see the "typical" error in the difference between the lines from a couple of different trips. In 3D, this looks the same as Ryan's plot.

Something definitely looks wrong as your track is shifted to the west - perhaps a coordinate system error but I'm no expert..?
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post #26 of (permalink) Old 11-30-2011, 09:17 PM Thread Starter
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Camshaft - Thanks for sharing your images of the same area. I'm thinking that perhaps the GPS satellites were "off" for that moment. The two (Outhouse junction and BT junction)are only a few minutes away at a good pace so might have been a blip. Maybe the same reason why on the way home today my GPS was reading -150 meters in North Van My Garmin car GPS sometimes shows my driving speed as 400km/hr lol for a few minutes - either I have a heavy foot or something strange is happening with those satellites Cosmic rays?
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post #27 of (permalink) Old 11-30-2011, 10:27 PM
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Quote:
quote:Originally posted by ubishops


... been reading quite a few reviews that say the TOPO Canada maps for example have lots of errors...
I have topo canada and I find it very good. There are errors but every map has errors. Some have more errors than others, but as far as topo; Topo Cananda is ok.

Now look at the backroads mapbooks, those are horible... do they even drive the roads they publish??? And if you ever get to see the gps maps by them its even worse, looks like baby puke on the screen. I dont think they have hired one geographer in the whole company.

Ok... enough side tracking...

Topo Canada is ok...

as for your your original problem; the other replies seem to be handing it ok.
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