Using Google Earth/Maps in the map development process
Posted 26 March 2008 - 01:56 PM
Posted 26 March 2008 - 02:18 PM
Email: email@example.com / Twitter: @redgeographics
Posted 26 March 2008 - 02:35 PM
I once use a G.E. placemarks with all of Quebec's golf courses because it was impossible to obtain GIS data containing all the info. But I still don't know if all the points where exactly at the right place... I was going a little blind on this one...
Posted 26 March 2008 - 03:07 PM
Posted 26 March 2008 - 04:01 PM
I am wondering how reliant cartographers have become on Google Earth/Maps for information and data. Both show satellite imagery and road data of varying resolution and currency. How often is it being utilized in official or - more likely - unofficially - in the creation of maps?
Slightly different angle to the question:
When we develop new layers or maps, you can bet that one place that layer or feature might be fact-checked is in Google Earth. If your map/layer doesn't fit positionally with what the customer sees in Google Earth/Maps, then there's something wrong with your data/map. Who gets the benefit of the doubt on that one? Of course this view is more centered around layer developement, but the implications for cartographic work are strong. I can think of several occasions in the past year where customers wanted to know the positional accuracy of our map features against Google Earth. IMO we aren't necessarily reliant on GE as a direct data source, but we are becoming more bound to it as a resource/reference tool, because our customers are using it. My 2 cents. Any thoughts on this angle? Sorry if I pulled the topic in a slightly different direction. Hopefully it's worth it.
Posted 26 March 2008 - 04:28 PM
Posted 26 March 2008 - 05:06 PM
Erin's post brings up a good point. In mapmaking as in politics, perception is reality. GE is definetely altering geographic perceptions. Whatever GE does every mapmaker's credibility will be matched against it.
Posted 26 March 2008 - 05:21 PM
- There are lots of alignment problems in Google Earth where the seams of images have been blended. This is usually most visible with roads that suddenly jump 20 or 30 meters. If I have ground truth, I can figure out which image is more wrong. If not, I just average them and hope for the best.
- Because of how the images are captured, there is distortion in the images, especially in hilly areas. Imagine that the satellite is directly overhead when it records the image. This will minimize the displacement of roads at different altitudes, because everything looks pretty flat from directly above. Now imagine that the camera is shooting at a 45 degree angle. Any features at an elevated altitude will be projected incorrectly because of this angle, but there's no way to see it in the images - they look correct. I figured this out when mapping my hilly neighborhood, as I was unable to get my recorded tracks to line up with Google Earth imagery, even when allowing for GPS error. It is possible to find the azimuth angle of the shot in Google Earth - it's buried down in the Layers.
- For large areas, I use a program called Stitch Maps (http://stitchmaps.com) which allows you stitch together multiple Google Earth images into a single large JPG for tracing. Very handy.
Hope this helps.
Posted 27 March 2008 - 06:18 AM
Posted 27 March 2008 - 02:03 PM
Posted 27 March 2008 - 11:22 PM
I don't read it that way at all. Copying of copyrighted imagery is prohibited, as is batch geocoding:
But finding out where something is, or confirming its existence/alignment using aerial views is pretty clearly within bounds. Standard US copyright laws apply, by which factual information is considered public domain, but its representation may be copyrighted.
Also, you may not use Google Maps in a manner which gives you or any other person access to mass downloads or bulk feeds of numerical latitude and longitude coordinates.
would seem to me to imply that they don't want you redistributing Google Maps-encoded information outside the organization: that is, you can't screen-shot Google Maps and re-post that screenshot on your web-site. You can only embed Google Maps live using the terms of their API.
For business users, Google Maps is made available for your internal use only and may not be commercially redistributed, except that map data may be accessed and displayed by using the Google Maps API pursuant to the API terms and conditions.
Posted 31 March 2008 - 08:21 AM
US Census Bureau
Posted 08 April 2008 - 11:49 AM
I used images from GE a few times for some projects of mine and I can tell you that they have positioning errors between 20 and 25 meters. I checked this against orthophotos purchased from the gouvernment.
Posted 11 September 2008 - 04:56 PM
I have been using Google Maps more and more. See http://waterquality.lcra.org and http://crwn.lcra.org . The production process is better now that I have figured out how to use ArcGIS server produce tiles to overlay on Google Maps. The watersheds and rivers and streams on the maps originated as ArcMap MXDs.
Hi Rich, This is my first time on this forum but saw your posts and maps you created from ArcMap. I'm looking for a simple way to make a bunch of maps accessible to the public without having to create and manage an internet map service. I'm searching through references on line but need a quick couple of suggestions for a short deadline. Can you tell me briefly where you started and is the google interface a free one? Thanks, Kristal
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