Not to sound cynical, but what is it that these 500 MB virtual tours
accomplish that could not be done with a series of panoramic JPEGs
totalling well under 1 MB?

The panos are "well under 1 MB" they are 500 K as in
KILOBYTES not 500 Mb as in MEGABYTES. I make the panos at 700 pixels
high and show them in a 500 pixel high window to maintain some quality
and size for "screen viewing".
Monitor screens only resolve 72 pixels per inch so anything of higher
res is a waste of bandwidth.

It's nice to see these eastern rivers, but personally I would prefer
higher-resolution still images.

Apples and oranges....................;+D

Different strokes for different folks..............;+D

Besides when you stitch together anything shot from a pivoting camera
on a central axis then make it into a 2D flat image you get beacoup
distortion. That should be evident in the 2D thumbnails in the index
page I posted.

There are only a handfull of veeeery expensive film panoramic
cameras that will shoot 180 deg images "without distortion". If you
would like to become a patron of the arts and buy me one and then also
fund the expense of film/processing/printing and scanning I would be
delighted to post single hi res undistorted 2d 180 deg river images
all day long for your viewing druthers..........;+D

You're preaching to the choir when you're talking single flat images
as I come from the Ansel Adams School of photography and I do plenty
of that. The vast majority of all the river images on my website at
loshombresdelrio.com are all 2d images. This is just something new
in addition to what I have been doing for years. I happen to be having
lots of fun doing the virtual panos and add to it that it is a really
great way to "virtually" experience being there. I am even finding
clients that want this kinda work for their architectural and
commercial spaces.

"The times they are a changing"
Bob Zimmerman (aka Bob Dylan)

Regards,

Pepe