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Between Cancer and the Google Earth use for the cadastre

From a good humor moment with a Dutch friend, this day, I rescue some similarity between the process that leads cancer in clinical psychology and Google Earth romance with wrong purposes:

Stage 1: Fright.

google earth precission
A technician goes to field in response to a measurement request of an owner who wants to sell; He checks that there are new buildings that are not seen in the cadastral map. Then comes to the office and sees that the 40 years ago orthophoto only shows vineyards on the periphery, with a great plot in rustic conditions.

He calls the technician who has been there 23 years, aging with a stereoscope hung to the neck and a worn leroy which only makes fonts for letters; after fighting on overlaying one layer on the other, certainly identify there is just in map what is in the picture.

So they decide to resort to the last year novelty; Google Earth has reached 2004 and shows a colorful orthophoto which shows recent buildings.

Then it begins the panic.

The plot coordinates do not match with the map ones; they are offset more than 20 meters.


-Be careful-. The quaternary tells to him. -Ancient aliens did those coordinates, and only they can change them.

Aware that Google can not be so wrong, move its entire cadastral layer to match the image. Then call his superior and impresses him showing the digital terrain model that matches with the cadastral layer that has been exported to Google Earth.

Thrilled with novelty, the commoners commission’s head prompts him to issue plans of each property, in order to sell to all residents at a better price “plots certifications that coincide with Google Earth”… and now in WGS84!… SEO optimized!

Stage 2: Denial

Two years after Google appears with an image that says 2006, the technician assumes that the image is more recent, he realizes that the building location is almost 6 meters shifted in south east direction of where the polygon moved, now drawn in green.

It seems surprising to him that now the printed maps’ coordinates are not good nor with the original maps neither with the Google new image. At this time the hand-drawn maps are abandoned in a bath which became winery since the day the Quaternary was fired.

His fear becomes a denial, because he can not accept that Google is wrong, not this time. So that leaves the property and the entire city where has been moved, hoping that the problem will resolve by itself.

Even knowing this, he decides to issue new certificates based on the new coordinates, with an offset rounded up to 6 meters.

catastro google earthState 3: Acceptance

Three years later Google appears with a new picture of 2009, and as you can see, the detail is much clearer.

He noted that the building has not the shape in the way he had interpreted.

It coincides with the last year location, so that he ends up accepting that his plots are displaced 6 meters… so he decides to issue other certificates with displacement, although this time without rounding.

He is surprised noting that the image has the new building built against the plot, so it comes to the conclusion that there can’t be more accurate information; so he moves all his mapping 6.47 meters at an angle of – 27 degrees.

The old quaternary goes to the office for sales and purchase process and remains scared seeing that the coordinates are strange. Try to make suggestions or find the source but then surrenders when they showed him themed shapes based on the constructive type.

Stage 4: Death

He decide to wait one more year, to 2010, and goes to field to do the property appraised value from the new building which is in the image. And at the same time to brand new wonderful equipment whose advertising is not paid to mention… 19 centimeters of accuracy, without post-processing.

Place the GPS and see that the coordinate is offset, make another test for 15 to 25 minutes and the coordinate confirms that it is … quite moved. Leave the GPS taking a longer reading while greeting the in front property new owner; he invites him to have coffee in the corridor overlooking the GPS that is practically cooking in the midday sun for almost 40 minutes.

The neighbor replied him that had bought the property three years ago, and has already gone to enroll it to the Land Registry, which now requires plans with precise coordinates. UTM WGS84… SEO optimized!

With some fear and desire to pee, he requests the property document and it takes him out of doubts:

cadastre precission

He went to register the plane with the property tax certification that has provided the commoners commission in 2007, and has told them he appreciates they have done an upgrade as it is now certain that the two neighbors’ demand will have no justification because he has a recent plane while theirs has more than 30 years.

Take measures one another, over and over again. Get more accurate device, and finally ends up convinced of the reality:

– Google property measures are displaced 23.87 meters!

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