My Tracks off on Google Earth

[+Cobber99]

So my tracks on or off road all seem to be a tiny bit (approx 15 yards) off between what my GPS records and what Google Earth shows. While I have read that this is common, I am curious if there is a way to get the two data sources to align? Here is an example of the phenomenon I'm talking about:

 

[smokingpipe]

I read it somewhere that Google Earth can be off 100 ft. when using GPS. I think it was on the Google Earth web page.

[+Cobber99]

I read it somewhere that Google Earth can be off 100 ft. when using GPS. I think it was on the Google Earth web page.

Yeah, I read that too but I don't have a ton of options on the Mac. Just wondering if there is a way to adjust somehow, but no biggie I guess.

[+allory]

Its a pain, but I have taken the data from the kml file into excel and subtracted a certain amount from both lat and lon to get the track log lined up with what shows on Google Earth. When you're creating a geologic road log for educational purposes its handy to have things look correct.

[robertlipe]

What you're seeing is an imagery alignment error. You should report the details of that in the appropriate forum of the Google Earth Community.

[planewood]

Yep, GE images can be registered badly sometimes. Here at my house it's almost dead on. At my country place, the images are shifted east about 10'-12'. Other places I've see it off by 50' or so. Only way to know for sure is to be able to see a surveyed benchmark or triangulation station in the GE image which requires an image with a high degree of resolution. High res images in GE are usually only found around high population urban areas.

 

But, poor satellite geometry or poor reception can cause your GPSr to be consistently off too. To help eliminate poor satellite geometry, use the Trimble Planning Software (free at the Trimble web site) and only go out when the satellite geometry is good for your area (low HDOP). To help maximize reception, use an external antenna with an unobstructed view of the sky and go out on clear days or nights when the air is crisp and dry and the HDOP is low. Clouds or high humidity can adversely affect reception. Have WAAS turned on too.

 

If your reasonably sure that your coordinates are fairly correct, then download the highest resolution aerial photo's (jpg format) you can find and then 'overlay' them over the GE image and alligned to your coordinates. The USAPhotoMaps software (shareware) is a good way to grab large aerial photo images. It may take a large amount of stretching or squeezing and rotating in GE to get it alligned.

 

Anyone know how GE registers the satellite images? What are they using for a basis or comparator?

[+Cobber99]

Yep - the Google map in my area is indeed shifted. I reported it to them (didn't see a specific section of their forums for it) via email. The USGS maps were dead-on. Thanks for the tip!

 

Quick question:

 

Which format if more universal/preferred for exchanging GE data: KMZ or KML? I want to throw some up on my hiking blog, but want to offer the best format.

[robertlipe]

KMZ is just KML that's compressed.

[+Cobber99]

KMZ is just KML that's compressed.

 

I have started a hiking blog for myself and am going to link to the track for each one in KMZ format in that case. Thanks for the help! I just wanted to be sure that the format would be universal.