Re: Bolex 3D

[P3D <CJMCE@xxxxxxxxxxxxxxxx>]

>>P3D Bob Wier <wier@xxxxxxxxxxxxxxx> Writes:
>>I remember the first few times
>>I used a video cam, I had to keep reminding myself that holding down the
>>"shoot" button wasn't costing me $5 a minute...

Larry Berlin said:

>That's about how I feel about the potential of digital imaging. Film and
>processing are pretty expensive by itself and when you shoot stereo you
>shoot two frames or more for each image making it double in cost.

>With a good variable base stereo digital camera you could record as many
>side by side frames as required for each image for practically nothing. On a
>typical outing for pictures instead of running out of film and thnking of
>the enormous developing cost ahead you could come back with hundreds of
>images ready to process however they might be needed, again for almost
>nothing per frame.

>Of course the digital equipment is expensive and to be really practical a
>digital camera needs to be easily hooked up to a computer that is near where
>you are shooting with lots of disk space for storage, but considering that
>computers and laptops are so useful for so many other things it's not like
>setting the equipment aside when done shooting until the next opportunity.
>This is especially useful if your final image needs are for online
>presentations.

>Here's hoping some new stereo photo opportunities arise in the near future
>based on digital possibilities. Maybe one of the digital camera mfg's will
>see the light? 

I've been using some Kodak DCS 460 Digital cameras for about a year now, and I
find that to be exactly correct.  I DON'T have to worry about the cost of the
imagery, I can shoot as much as I want and cull out the bad or useless shots
later in the lab/office.  The "turnaround" is quite gratifying also and most
important at times...

A couple of months ago, I was called to a ship repair yard to do "Hull Offsets"
for a tugboat.  The vessel is about 50 years old, and the owner wants to install
a mid-body bow thruster (steerable).  To accomplish this, a Naval Architect 
must do a stability analysis to see if such a retro-fit is safe.  The vessel did
not have existing plans as to the dimensions (as-built) of the hull, and the
traditional method of obtaining "Hull Offsets" is with a surveyor's crew,
tape measures, electronic distance measuring equipment, theodolites, total
stations, etc., etc.  Furthermore that takes a lot of time and a lot of money...

My objective was to minimize the time spent in the dry dock and still obtain
reliable dimensions of the "Hull Offsets".  I showed up with one DCS 460 camera
and a Naval Architect.  The Tug boat was made available to me in the dry dock at
12:30 PM.  With three men, we used hammers to sound for the bulkhead lines on
the hull ("bong, bong, dink, bong, bong") - the "dink" is where the bulkhead is
found; and small round (1/4 inch diameter) photo targets were then glued onto 
the hull forming lines of white dots going up from the keel to the gunwale.
This process was repeated and repeated until the entire side (one side) of the
vessel was targeted with lines of little white dots representing every bulkhead
in the vessel's hull.  It took four hours, we were finished targeting at 4:30PM.
I then took 15 minutes to survey four (X-Y-Z) control points, and another 15
minutes to take 52 digital photographs (350 Megabytes compressed).

I shook hands, returned to the lab & transferred the imagery to my PC and 
verified the exposures.  I called the shipyard's Naval Architect & told him
he could re-float the vessel; I was finished with it.  Total dry-dock rental
time: 1/2 day instead of the usual 3 days.

Analysis time: one person (me) 12 hours.  Result: accuracy of +/- 0.33 inches on
all targets for (X-Y-Z) coordinates for the entire 125-foot long tugboat.  The
stability analysis was then complete with a report to the owner BEFORE it would
have taken a regular Survey Crew JUST to do the field work alone.

Out of the 52 images I took, I actually used about half.

Digital cameras are nice once you get over the sticker shock...


Clifford J. Mugnier  (cjmce@xxxxxxx)
Topographic Engineering Laboratory
Department of Civil & Environmental Engineering
University of New Orleans
New Orleans, Louisiana  70148
Voice: (504) 286-7095
FAX:         286-5586


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