# [Talk-GB] Measuring building height

Neil Matthews ndmatthews at plus.net
Tue Mar 19 20:51:14 UTC 2019

```So, I just tried this and I think it has a reasonable chance of giving a
reasonable result.

Take a photo of a car outside the building. Measure number of pixels for
the car and number of pixels for the building and the height can be
approximated by:

building_pixels / car_pixels * car_height_in_m

I reckon an average of 1.5m might be reasonable for the car height --
otherwise use something more detailed:
https://www.automobiledimension.com/ford-car-dimensions.html

Obviously, the further the car is from the building the less accurate
the measurement will be.

Cheers,

Neil

On 19/03/2019 16:23, Tony Shield wrote:
>
> Hi
>
> Been figuring out how to do this for a while - my solution-
>
> rule - I used 30cm (aka 1 foot), calculator, known length of arm - in
> my case .6m, OSM map to measure distance from target.
>
> With hand holding rule vertically measure the target height against
> the rule for rule height, this is the key measurement, note the
> measurement point. From the map measure the distance from the
> measuring point to the target
>
> With this information and using proportions (which is what a tangent
> is) -
>
> target height = (rule height in metres * distance from measuring point
> to target) / length of arm in metres.
>
> Using this technique I have this morning measured known height of of a
> local landmark, and the unknown height of a building. The known height
> of 50m measured 8cm at a range of 375m. The unknown height of the
> building with 5 floors was calculated to be 20.7 metres which would on
> the face of it be realistic (from 3cm and 414m). (Botany Bay mill in
> Chorley).
>
> TonyS999
>
> On 19/03/2019 09:30, Brian Prangle wrote:
>> There are also theodolite apps for smartphones
>>
>> On Tue, 19 Mar 2019, 00:17 Rob Nickerson, <rob.j.nickerson at gmail.com
>> <mailto:rob.j.nickerson at gmail.com>> wrote:
>>
>>     For building heights why not try using a laser measure? Those
>>     with a Pythagoras Measurement mode should automate the
>>     calculations for you.
>>
>>     Price has fallen a lot over the years. Seems like even a basic
>>     £30 device is sufficient.
>>
>>     Best regards,
>>     Rob
>>     _______________________________________________
>>     Talk-GB mailing list
>>     Talk-GB at openstreetmap.org <mailto:Talk-GB at openstreetmap.org>
>>     https://lists.openstreetmap.org/listinfo/talk-gb
>>
>>
>> _______________________________________________
>> Talk-GB mailing list
>> Talk-GB at openstreetmap.org
>> https://lists.openstreetmap.org/listinfo/talk-gb
>
> _______________________________________________
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-gb
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20190319/978dd049/attachment.html>
```