# Google earth glitches

**URL:** <https://boards.straightdope.com/t/google-earth-glitches/608902>\
**Category:** Factual Questions\
**Created:** [January 9, 2012, 8:00am UTC](https://boards.straightdope.com/t/google-earth-glitches/608902 "2012-01-09T08:00:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![GeddyClaypoolBurton](https://avatars.discourse-cdn.com/v4/letter/g/ce7236/32.png) [@GeddyClaypoolBurton](https://boards.straightdope.com/u/GeddyClaypoolBurton)\
**Post date:** [January 9, 2012, 8:00am UTC](https://boards.straightdope.com/t/google-earth-glitches/608902/1 "2012-01-09T08:00:46Z")

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On rare occasions, I have found roads and other lines on Google Earth (fences, etc.) that do not line up correctly; the road will be going straight, and then when it switches to another satellite image, the road will be shifted over to the side quite a bit. What do you think causes this? Note: If it has to do with imperfect satellite picture stitching, then how/why do these imperfections happen? :dubious:

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**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\
**Post date:** [January 9, 2012, 8:21am UTC](https://boards.straightdope.com/t/google-earth-glitches/608902/2 "2012-01-09T08:21:01Z")

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Google earth is made up of stitched together satellite and aerial photos derived from different sources at different time periods. They don’t take any photos just for Google Earth; they compile already existing but scattered information.

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**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\
**Post date:** [January 9, 2012, 8:59am UTC](https://boards.straightdope.com/t/google-earth-glitches/608902/3 "2012-01-09T08:59:06Z")

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Satellite photos are seldom shot from a position perpendicularly above the subject (you can observe this by looking at the shots of cities - you can often see the sides of the buildings, as well as just the roof)

As a result of this, the photos need to be adjusted - as well as adjustments for the curvature of the Earth (in general and with respect to the non-perpendicular original image). All those adjustments, plus some other more subtle ones, can add up to inaccuracies in registration of map tiles, especially as there will have been a limit on the mathematical precision of the calculations underlying them.

Plus… conventionally, all of those adjustments are done with a view to translating a curved globe into flat maps - Google is then trying to fit those flat maps back onto a curved globe.

On a related (but somewhat separate) topic, image stitching issues also occur in the street-level photographic data, but I think that has a different cause (I believe the streetview data is stitched on the basis of matching similar parts of the edges of neighbouring images) - my favourite example of this appears in Google Maps streetview (as well as its counterpart in Google Earth) - this cafe is near where I work. The sign above the door at [this](http://maps.google.com/maps?q=clarendon+road,+portsmouth&hl=en&ll=50.781347,-1.080309&spn=0.001693,0.003664&sll=37.0625,-95.677068&sspn=34.724817,60.029297&vpsrc=6&hnear=Clarendon+Rd,+Portsmouth,+United+Kingdom&t=m&z=18&layer=c&cbll=50.781347,-1.080309&panoid=LCAp6umMFFUGw_bfpGeoxQ&cbp=12,224.9,,1,1.81)cafe actually (that is, in the real world) says “Big Breakfasts’”