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  #21  
Old Posted Mar 15, 2021, 3:19 PM
Alpha Alpha is offline
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Is it possible to determine the height of structures from Google Streetview pictures?
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  #22  
Old Posted Mar 15, 2021, 4:51 PM
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Quilmeño89 Quilmeño89 is offline
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No, unless you have a precise reference that allows you to do the rule of three. But for that you need distant photos without perspective and the result will only be an estimate.
Using different resources, I have been able to estimate heights in this way with great precision, but the only way to check it is with Google Earth 3D or with official technical information.
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  #23  
Old Posted Mar 15, 2021, 5:52 PM
Miki1993 Miki1993 is offline
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If the place you're looking at is relatively flat and there are other buildings with known heights nearby, you can also compare shadow lengths for a rough estimate.
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  #24  
Old Posted Mar 20, 2021, 11:51 AM
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Artemco Artemco is offline
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I calculated height of structures in GoogleEarth comparing length of their shadows or themselves if view is much inclined with known structures
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  #25  
Old Posted Aug 20, 2021, 8:25 PM
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Anders Franzén Anders Franzén is offline
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I'm currently redoing some of my drawings I did for San Francisco 6-7 years ago.

Comparing the given height of the buildings with Google Earth, it becomes apparent that the official height in many cases only is the "main roof height", not counting spires, penthouses and other structures that I wouldn't want to leave out of the drawing.

I've already uploaded some drawings. More are to come and I also changed a few of my NY drawings for the same reason. But my lists of Hong Kong buildings I want to draw is still quite long, so it all my take some time. (For that city, I rely almost completely on Google Earth)
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  #26  
Old Posted Sep 25, 2021, 1:47 PM
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Highriser_P_28 Highriser_P_28 is offline
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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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  #27  
Old Posted Sep 27, 2021, 8:51 AM
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Quilmeño89 Quilmeño89 is offline
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Quote:
Originally Posted by Highriser_P_28 View Post
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.
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).
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  #28  
Old Posted Sep 27, 2021, 5:00 PM
mrnyc mrnyc is offline
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i believe to be most accurate you have to first figure out and use the average grade of the building and the land surrounding it and measure the height to the top of a structure from there.

the average grade can of course vary a bit from the site itself and from sea level and it's immediate surroundings.

so how far from the building do you need to go to look around at the grade?

i dk.

i've read anywhere from a few feet from the building to the 'area' around it.

so given that confusion small differences should be expected depending on what is reported.

large differences no though.
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