There's pretty much no way to avoid writing a large comment in
response to this. So, with apologies...

It was my focus for a long time to achieve perfectly photorealistic
rendering. I come from a gamedev background, and I've been fascinated
since around age ten about how to get a computer to paint pictures. By
17 I was writing game engines mostly equivalent to quake, and used
this portfolio to get into the industry. The next three years were
spent getting as close as possible to the bleeding edge of real-time
graphics development.

I remember having long debates with a colleague about what
high-dynamic range lighting "meant." "If we spin around in our office
chair, our brains do not suddenly change the overall brightness of
this office. Why should we be programming games to do this? Why is
everyone doing things that way?"

My concerns were of a more fundamental nature as well. What is a
diffuse texture? A diffuse texture is a well-understood concept in
realtime graphics. Anyone with a basic knowledge of shaders should
immediately recognize:

color = lighting * diffuse + ambient

Trouble is, it doesn't correspond to reality even slightly. It's not
even roughly close. It happens to look good to humans, and that's
why we use it. But the trouble was, the further I tried to probe
the mystery of realism in computer graphics, the more I ran against
this phenomenon of "We use X technique because it looks good."

So I turned to research papers. Books. The medical field. Everywhere
that was remotely related to possible breakthroughs in photorealistic
rendering. Research papers are excellent for assembling techniques,
but not results. The books in human vision and color science were more
promising, yet most of the industry seemed (and still seems) to pay
little attention to them. Compare a book about color perception to,
say, http://www.pbrt.org/ and you'll see a stark difference. Flip
through the table of contents and you get transformations, shapes,
primitives, color and radiometery, sampling, reflection, materials,
texture, scattering, light sources, monte carlo integration...

And for what? We know that these techniques simply do not produce
computer-generated videos that a human will identify as a real-life
image. It's not for lack of processing power. There is a disconnect
between the old rules and those that will ultimately result in
real-time realism, and you won't find it in that table of contents.

Now, the trouble with writing all of this is that if I knew how to do
it, I'd have done it already. It's a life-long search, and it's not so
easy to refute an entire industry without being (rightly) dismissed.
But if you wish to know what I suspect are the ways forward, it's
this: Get a camera. Take photos. Compare these photos to the results
of the algorithms you write. Iterate on your algorithms until they are
producing results that match something that already captures nature,
not our beliefs about how we ought to be able to capture nature. "Just
throw in physical models and presto!" has not thus far been true.

You'll notice, for example, that computer graphics in videogames have
plateaued. They get more impressive with each generation, but that
impressiveness does not get them progressively closer to looking
real. Nor should it. A computer game tells a story. The closer it
looks to real life, the more restricted the artists are, along with
the rest of the design of the game.

So we turn to the movie industry for hope. But it's restricted in
exactly the same way. The research papers are all along the lines of
new techniques to try, or studies of existing pipelines and how to
deal with their complexities. It's not fundamental research.

As someone who has spent his life in pursuit of realism in
computer-generated video, my recommendation is this: Read DaVinci's
journal. Pay attention to what each page is saying. He had to discover
from first principles what makes a painting look real, and why. You'll
notice that he spends most of his time talking about human vision and
our perceptions of color.

If someone is going to make this development happen, it's not going to
come from the game industry, and it won't come from the movie
industry. That leaves you. Hopefully this will encourage some of you
to pursue this. Once you accept that most of the computer graphics
industry isn't actually focused on achieving realism, you'll start to
develop your own techniques. My hope is that this will eventually lead
to a breakthrough.