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29 Jul 2024 16:28:32 EDT (-0400)
  Establishing scale (Message 1 to 2 of 2)  
From: Anthony D  Baye
Subject: Establishing scale
Date: 22 Mar 2011 15:40:01
Message: <web.4d88fa52415904d4d7f39bd00@news.povray.org>
I'm trying to establish dimensions from a set of photographs.

http://www.postlerferguson.com/work/paper-oerlikon

The pictures are of a model of an Oerlikon 20mm twin anti-aircraft cannon. (Made
entirely out of paper)

I wanted to model it in POV, but I can't find any dimensioning information.

All I know for certain is that the shells, which are contained in the boxes on
top, are 0.8 inches in diameter (which gives the inside diameter of the barrel)
and between 6 and 9 inches in length, depending on type.

I estimate that the Muzzle Brakes are about 18 inches long, but if I'm right
that would make the barrel alone about six feet long (without the Muzzle Brakes)

Any assistance would be appreciated.

Regards,

A.D.B.


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From: Trevor G Quayle
Subject: Re: Establishing scale
Date: 22 Mar 2011 16:05:01
Message: <web.4d8900b2a623187781c811d20@news.povray.org>
"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:
> I'm trying to establish dimensions from a set of photographs.
>
> http://www.postlerferguson.com/work/paper-oerlikon
>
> The pictures are of a model of an Oerlikon 20mm twin anti-aircraft cannon. (Made
> entirely out of paper)
>
> I wanted to model it in POV, but I can't find any dimensioning information.
>
> All I know for certain is that the shells, which are contained in the boxes on
> top, are 0.8 inches in diameter (which gives the inside diameter of the barrel)
> and between 6 and 9 inches in length, depending on type.
>
> I estimate that the Muzzle Brakes are about 18 inches long, but if I'm right
> that would make the barrel alone about six feet long (without the Muzzle Brakes)
>
> Any assistance would be appreciated.
>
> Regards,
>
> A.D.B.

http://military.wikia.com/wiki/Oerlikon_20mm

Based on this the pipe length is ~1.4m (4.6ft), overall length ~2.21m (7.25ft).
Not sure what the reference is of these dimensions, but it sounds like you are
on similar track.

What I tend to do is dimensions everything to a uniform scale that is convenient
(in, mm, pixels).  And then scale the entire maodel after by a known ratio
between the two scales.  E.G., measuring in pixels, the approximate length from
back to front of the barrel is ~501 pixels (416x279), assuming that this is the
total length 2.210m, I would then scale the entire model by 2210/501 to get it
into mm.


-tgq


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