On 20/03/19 07:51, Neil Matthews wrote:
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.
The further the camera/photo is from the building the better too. Less
camera distortion.
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
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