The issue of the accuracy of satellite and orthorectified images of Google Earth is a record question in the search engines, in these days in which confusing precision with tolerance is as easy as losing the GPS in the taxi, it would be good to make a couple of analyzes about the convenience or not of using this data for serious work.
This satellite is called Worldview I, Which will work in conjunction with a Quickbird satellite, the images will have a pixel resolution of 50 centimeters (currently 1 meter) and will be able to capture 600,000 square kilometers per day, which they currently get in a week.
This often misleads those who only concentrate on the final product (maps) and not on the intermediate products of survey and its photogrammetric origin which is what allows us not only to have products but also their level of precision and pertinence. When using Google maps material For local purposes It can be corroborated by the lack of precision, sometimes up to 30 meters, since a satellite image requires a dense network of first order and local checks for its rectification. Not that it's bad, it's for the purpose of Geographical web which is the way Google Earth calls that layer.
For those who still want to do cadastre with ortos of GoogleEarth, here is an example of what will be found:
This is La Jaguita, Comayagua, Honduras; Observe how you see in the splicing of images the repetition of the same complex of buildings, 36.51 meters to the northeast.
We use two GPS Magelan Mobile Mapper, one as a base, another to raise points and after making the differential correction, we compare it with an orthophoto created with aerial photography of three years ago with 5,000 flight; the GPS data matches perfectly with the orthophoto but not with any of the Google Earth images, one of them is 23 meters to the northeast, the other to 19 meters, but the displacement vector has a different angle.
In this respect it is not possible for us to question a system, which is the best that many of our towns can have, where cartographic information will not arrive in the next 10 years, and to top it all is free; What is important is that we are aware of its relevance and limitations.
To meditate I leave you this point of the terms of Google Earth, the one that nobody reads and only presses the "I accept" button:
E) NO ADVICE OR INFORMATION, WHETHER ORAL OR WRITTEN, OBTAINED FROM GOOGLE OR THIRD PARTIES OR THROUGH THE USE OF THE SOFTWARE, GRANT ANY WARRANTY THAT HAS NOT BEEN EXPRESSLY SET FORTH IN THESE TERMS AND CONDITIONS.