Google Earth vs Professional Surveyors
Google Earth is an excellent software, very powerful, which helps us find places, coordinates, aerial photography, distances, etc., but expert application management does not make the user a land surveyor. These are some of the reasons why we must take with caution the data we obtain through Google Earth:
The UTM coordinates shown by Google Earth are undoubtedly an exceptional help when trying to locate a site, but you must be very careful, these coordinates must be taken as APPROXIMATE COORDINATES. These coordinates should never be taken as true for a professional job or trying to georeference a point or a map, to obtain real and reliable coordinates there are the correct tools like the survey grade GPS.
The images that Google Earth shows are a collection of photographs obtained from various sources such as satellites, planes, drones, etc. that Google acquires in a massive way and that through a powerful algorithm they manage to form a mosaic, but these images are not reliable due to that are not correctly georeferenced or scaled, that is, the photo is moved from the original site and / or does not have the original dimensions, sometimes up to tens of meters, to verify the above, the following exercise can be done, we can mark a point on the image to then change the various photos over time, clearly you can see that the point is staying in various places.
The elevations of the terrain that Google Earth shows us are obtained by analyzing the depth of the photographs, so it helps us to have an idea of the existence of a hill or some material bank of considerable size, but it will be totally useless if what you require is to determine the levels for an architectural project. One way to test it is to put the pointer in the courtyard of some property, this will give us an elevation, now hover over the roof of a nearby home and you can verify that there is no change.
Regarding the measurement of the distances in the images, it turns out that they will not be real because the photos are not scaled correctly and therefore will have errors of several meters in the measured length.
In short, Google Earth is a useful tool for a previous analysis, but if what we want is to know dimensions, areas, levels and / or real coordinates, either to verify the measurements of a land that you want to acquire or to carry out a project contact an expert on the subject, go to a competent Surveyor.
Servicios de Ingeniería Topográfica desde 1992.