Quote:
Originally Posted by Highriser_P_28
I compiled some height values obtained with Google Earth which I'd like to submit as corrections eventually. The main issue is that the level of agreement with the published values varies wildly: while a few are (almost) exact matches, some differ on the order of a few meters, and others (especially for older buildings) by even larger amounts.
Since there seems to be some consensus here in using GE as an acceptable source for heights, I ask at which point a published value can be deprecated in favor of ones obtained with GE (such as a cutoff)?
A consideration that might apply is that the 3D area I was working with isn't of quite good quality, and with areas like the ground level close to buildings having small irregularities generated it becomes hard to get heights accurate down to the meter.
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You have to analyze each building, compare heights with surrounding buildings, make calculations, among other things. Then you will be able to figure out which buildings are actually the published height and which ones match Google Earth.
Generally, the height obtained with Google Earth is the actual height of the building, rounded. However, it may happen that there's some element on the roof that Google Earth didn't model, so that height must be estimated.
The differences between the published values and those of Google Earth can be due to several reasons. For example: difference between the projected building and the constructed one; omission of pinnacles, upper technical floors or other elements of the roof when the height was declared; or a simple mistake.
That's the reason why each case must be analyzed separately.
From what I could see in all these years, Google Earth is the most reliable source to know the real height of a building.
The technical drawings don't always show the final project, which may have some unforeseen addition once built, increasing the final height. So you can trust them, but as long as the building looks exactly like the drawing.
Google Earth doesn't give you the exact height, with all the decimals, but it does give you the rounded height, which is the one they often use in commercial publications (with the remarkable difference that, in these publications, they often round up to the next zero, so a building measuring 87 m would be listed as 90 m; Google Earth only rounds decimals, that is, a 86.65 m building will be shown as 87 m).