[tech-3d] Re: Stereo Base Calculation With a $20.00 Handheld

["Michael K. Davis" <zilch0@xxxxxxxxxxxx>]

Hi Allan,

>Date: Fri, 17 Nov 2000 21:51:16 +1100
>From: "Allan Griffin" <agriffin@xxxxxxxxxx>
>Subject: Re: Stereo Base Calculation With a $20.00 Handheld
>
>Mike,  would you kindly explain this point to me:  "Are you proposing that
>the fixed separation provided by the stereo cameras used by the bulk of us
>for general subject matter (subjects other than macro or hyper) be discarded
>in favour of a continuously variable inter-lens separation"?

I haven't made an argument against using fixed-base stereo cameras.  The
very title of my article makes it clear that it is about calculating stereo
base, which is entirely irrelevant if you can't vary the separation.  It's
as if I wrote an article about a great way to adjust the chain on a
bicycle, but you are suggesting I object to the use of unicycles.   For the
record, I have no objection to your use of fixed separation stereo cameras. 

>If not, then may I assume that you are talking here solely with reference to
>macro and hyper subjects and not the wide mid-field?

Your assumption suggests you are convinced that a fixed separation camera
satisfies your requirements for "mid-field" subjects.  I personally don't
find this approach satisfying, but let's agree to respect each other's
tastes.  It is my personal preference to use a variable base, following the
General Solution, for nearly every situation, including the mid-field.  Can
you say, "There is no right or wrong..." as I did in my original article?
There's no need to debate subjective aesthetics.

>At the end of this unduly long adventure into so called simple math, you
>say:  "I encourage review, not just for my edification etc. . . . . . . . .
>. ."
>
>Thats an interesting point.  If what you have written is theoretical, it
>would be appreciated if you were to back it up with practical stereo pairs
>demonstrating the statements made and post such on a website to which we
>could have access.

Allan, your challenge will go unrequited.  I don't have a scanner.  I don't
have a web site.  I don't have the energy, the time or the interest to
defend my approach to stereography.  I might be wrong, but from my
perspective, your invitation smells like a simple dare.  Fortunately, I can
rest assured that not everyone will leap to the narrow conclusion that my
refusal to participate warrants impeachment of all that I have written.  

The math speaks for itself.  It fits the geometry perfectly.  I'm not much
of a mathematician really - all I did was migrate the formula John
Bercovitz uses into a $20.00 calculator.  I think it's a very neat way to
handle the calculations in the field and I suspect my intended audience
(those who don't use fixed-base cameras) would enjoy trying it. 

My essay on how the 1/n rules do not closely conform to the General
Solution was equally irrelevant to users of fixed-separation stereo cameras.

>Kindly respond, Mike.  I see that you implicate John Bercovitz and Steve
>Spicer in your theories.  It would be of particular interest to me if these
>fine stereo workers could, in a relatively short amount of space, either
>confirm support or otherwise.

I would prefer to say that my theories embrace rather than implicate these
gentleman, but yes, it would be interesting to receive feedback from
someone willing to critique the technical aspects of my article.

Let me close by quoting my original article:

"...I'm convinced there is no right or wrong in how you go about
determining stereo base as long as the results you get are pleasing to your
eye and hopefully to your audience.  If the method(s) you choose allow you
to accurately pre-visualize the results you desire, terrific - you must be
doing something right."

Mike

>
>Allan
>        *************************************
>
>Sent: Friday, November 17, 2000 6:29 PM
>Subject: [tech-3d] Stereo Base Calculation With a $20.00 Handheld
>
>
>Mike, you wrote:
>> Here's an easy way to calculate the General Solution for stereo base (that
>> which John Bercovitz and others use), with a $20.00 calculator (the HP 30S
>> Scientific) that prompts you for each variable, allowing you to overwrite
>> only those you wish to change, before calculating the stereo base in
>> millimeters.  Using this document to program the HP 30S, you can get base
>> figures in less than fifteen seconds after turning it on.  The Hewlett
>> Packard 30S is a thin, light, two-line calculator that fits the bill
>> perfectly.
>>
>> If you oppose the General Solution approach to calculating base, you might
>> want to skip down to the section I call "Comments Regarding the Percent of
>> MAOFD Desired."  As old as the debate is, I believe I have shed some new
>> light on the subject of the 1/30 Rule vs. the General Solution and you'll
>> even be pleased to find I make a case for using the 1/15 Rule.
>     ***********
>Material in this area deleted.  Please refer to original posting.   Allan
>      ***********
>>(Yes, I'm new to this sport, but quite obsessed!)
>
>> I vigorously encourage critical review of this article, not just for my
>> edification, but for the people I hope it will serve.
>
>> Mike
>>
>>
>>
>> >
>


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