P3D Re: JPS format images

["Greg Wageman" <gjw@xxxxxxxxxx>]

From: John Toeppen <toeppen@xxxxxxxxxxx>


>The software allows you to open bmps, jpgs, most of what you might have
>as source images and paste them into DDS windows.  You get to crop the
>images in a difficult and tedious way, and finally view them. [snip[


All of this is true only if you run the Windows 95 operating system on
your computer.  No other operating system (Linux, SunOS x86, Mac,
Windows NT, OS/2, etc.) is supported.  I run NT4.0 and Linux and I
cannot use any of VRex's software succesfully.  Oh, it *trys* to run,
but simply doesn't work.  I have reported this to them and their
response was effectively to shrug.  That's their choice, but my wallet
is voting elsewhere.

>You can view JPEG (JPG)images using DepthCharge.  So, any software that
>writes JPEG can be read with DC.  The stereo pair has the right image
on
>the left and left on the right...NOT like a stereo card.  This allows
>crosseyed viewing of any size image on your monitor. Parallel viewing
>does not make good use of your display's pixels. Crosseye is easy and
>good if you know how - I crosseye preview my Realist rolls before
>mounting.


The JPS standard allows for a wide variety of internal representations
such as anaglyph, interlaced, over-under and monoscopic images,
strangely enough, which the JPS "stereo descriptor" accounts for.  In
the absence of said stereo descriptor, the assumed arrangement is a
right image first, side-by-side stereo pair.  So by renaming  a JPG
stereo pair in this format to JPS, one takes advantage of this default
assumption.  But it is not the only possible internal representation by
any means, and software which assumes it is may be in for quite a shock.
I know that you know this, but I wouldn't want to lead anyone astray.
:-)

I recognize that your endorsement of cross-eyed viewing is an opinion,
but I don't agree.  Cross-eyed viewing can be more difficult than
parallel viewing, depending on the image size.  The larger the image,
the more your eyes must cross to fuse the pair and view them in stereo.
A decoupling of this often-severe convergence and the required
accommodation at a much greater than normal distance for that degree of
convergence is also required, and can be difficult to achieve,
especially in older eyes which aren't as flexible as young eyes (says
this 40-year-old from personal experience).

At least many producers of parallel stereo images recognize that there
ARE size limits, and constrain themselves to reasonable dimensions.
Cross-eyed viewing also results in a subjective "liliputianism" not
unlike hyperstereos, which is unrealistic in the average scenic image
case.  While this is probably a physio-psychological phenomenon (where
the extreme convergence is providing an inappropriate distance cue for
the subject matter) and can be overcome with experience, the beginning
cross-viewer (transviewite?) will undoubtedly experience it, with
varying degrees of consternation.

As you might guess, I generally find parallel viewing a far more
satisfactory stereo experience, insofar as I cannot get DepthCharge to
properly interlace my display for use with the Vrex LC shutter glasses.
If Vrex would fix their software to run on NT4.0 successfully, I
wouldn't hesitate to use it and recommend it to all my fellow System
Administrators and consultants here in the SillyCon Valley...

Also, John, I think it is only fair for you to note that Vrex offers a
CD-ROM of your images for sale on their Web site, so your endorsement of
them is not without some profit motive on your part.  Again I'm not
saying there's anything wrong with this, just that it is considered
ethical to divulge such a connection.

     -Greg W. (gjw@xxxxxxxxxx)





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