Greetings all:
I agree with Geoff, and now others.
May I bring the perspective of a very new member to this group?
Although I have been studying sundial design for many years now, I only
recently joined.
Sundials are not exactly the main topic at dinner parties and it was a pleasure
to find
, the
dimensions should be correct when measured in pixels.
Now back to perspective correction. Let's say I take a (digital) photo
of a vertical dial up a wall. The location forces me to take an oblique
shot. Let's also say I am sure that the dial (or its frame or setting)
is rectangular
What we see is determined by where we stand. This is a reality in so many
aspects of life.
This applies to sundials. We were all misled a while back by the distortions
from perspective on an excellent sundial design. This was a useful experience.
I have recently be trying to correct
Some well chosen words Roger!
Some time ago I found distortion in some CAD drawings I had printed.
From then
on I put a small square in one corner so I can check the correct scaling
in X and Y.
This can be an aid in pictures as well. Unfortunately, when taking
pictures you do
not always
: Calculating
dimensions from perspective pictures; reverse engineering
The new thread on reverse engineering, and the large
number who have asked me to explain how I calculate dimensions
fromperspective pictures (such as the Kratzer
dial at Oxford), prompt me topost the answer, rather than
The new thread on reverse engineering, and the large
number who have asked me to explain how I calculate dimensions
fromperspective pictures (such as the Kratzer dial
at Oxford), prompt me topost the answer, rather than replying
privately.
Given only a perspective painting or photograph
David Brown
Somerton, Somerset, UK
Email: [EMAIL PROTECTED]
Website: http://www.sundialsculptures.com
- Original Message -
From: J.Tallman [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Saturday, June 07, 2003 9:22 AM
Subject: Circles in perspective = ellipses
Hi John,
A 42° ellipse is a circle viewed from an angle of 42
Dear friends,
I have read your very interesting remarks on perspective.
I also have a Coolpix 990 and I am completely satisfied
with it. I have solved my perspective adjustements with
a Photoshop plugin, the Andromeda Perspective Filter, it
is simply wonderful. You can download a demo from
