[Radiance-general] A modern comparison of Radiance and other rendering engines

[Jan Walter]

Hi,

nice that someone still stumbles upon my images and render comparisons ;-)

> I also stumbled upon this comparison website:
> https://www.janwalter.org/RadianceVsYouNameIt/radiance_vs_younameit.html

To compare renderers is a really time consuming task and each renderer
is changing
over time, so one picture rendered today might look different in a 1/2
years time.
And to really be able to compare those renderers with some confidence
you must know
about all their parameters etc. A task which I like to spend my time
on, but still after all
those years doing it, I don't want to publish too many details, but
rather make people
download some files, install renderers and try for themselves.

But here are some thoughts:

- Radiance did have a huge impact on other renderers (and that we have
HDR and OpenEXR).
  That's why I called that comparison somewhat ironically Radiance vs.
YouNameIt. Some people
   got all the fame, but me and some others are old enough to remember
where things came from ...
- Other things which slowely made it into other renderers: Sun & sky
simulations, suddenly with HDR
  you could end up with over- or underexposed images -> exposure
control -> camera controls/settings
  which mimick real cameras etc. In the film world you had LUTs, now
everybody somehow/somewhat
  deals with color correction. All of this makes it hard to end up
with a "similar" image.
- Sure, other renderers are more user friendly, and there is/was some
money to make. I would say
   that integration into a DCC tool is sometimes more important for
the success of a renderer than
   the quality of the resulting images. For my tests I was using
Blender (most of the time):
   https://bitbucket.org/wahn/blender-add-ons (the io_scene_multi
contains Python scripts for
   Arnold, Indigo, Luxrender/PBRT, mental ray, Maxwell, Radiance, and
RenderMan compliant).
   None of this is production ready, I add only things I need
personally to do the next step and render
   the next comparison images ... and Blender has Cycles now, which
changes a lot:
   https://www.cycles-renderer.org/
- I started to collect Blender scenes (and scene descriptions for
various renderers) here:
  https://github.com/wahn/export_multi ... as you may notice some of
those scenes come from
  Radiance. I had to write an importer first, parse Radiance files,
store them in some renderer
  independent format which does not loose the provided information,
bring that into Blender and find
  tricks to e.g. keep primitives like spheres as those in case the
renderer in question can handle those
  directly. Use someheuristics to mimic material settings etc. ...
- After a while the git repository got too big, the files too large,
the scenes/textures too big/many ...
  So now I provide download links for scenes in various formats:
https://www.janwalter.org/download/
  All of them originate from a Blender scene, but I update them from
time to time and all of this is meant
  to make it easier for somebody else to just download the files for a
particular renderer without having
  to deal with Blender etc.
- Finally I started converting PBRT's C++ code to Rust (
https://www.rust-lang.org/en-US/ ) as a
  learning experience. Maybe someone wants to do that for Radiance one
day. Rust seems to be a fun language
  with safe multi-threading etc. Here is the current state (and a bit
of history about last year's development):
  https://www.janwalter.org/jekyll/review/2017/2018/01/01/happy-new-year-2018.html

Anyway, comparing renderers is really hard. Radiance is about being
accurate, others might look good and might be easier to play with. My
interest is in using Radiance (and others) for reference and try to
create similar looking images. Compare rendering times etc. An ever
changing world ... Here I was playing with false colors etc.:
https://www.janwalter.org/jekyll/rendering/radiance/2015/10/02/classroom-radiance_falsecolor.html
But I'm not an expert user of Radiance. Most of the people on this
list know much more about it.

I just wanted to give Radiance some credit for all the things which
made it into other renderers.

My 2 cents,

Jan

On Mon, Jan 29, 2018 at 8:52 AM, Dion Moult <dion at thinkmoult.com> wrote:
> Good morning all,
>
> Apologies if a thread like this already existed, but after searching the
> archives I could not find it.
>
> I am looking for a modern-day explanation as to what Radiance offers that other
> popular rendering engines (Renderman, Cycles, V-Ray, etc) do not. These all seem
> to use ray-tracing, solve the global illumination problem, use physical units
> (albeit sometimes not very obviously, and sometimes require a conversion
> factor), I see hints of illumination falsecolours out there, and can output
> unclipped HDRIs as final results... as you can see, at first glance to an
> inexperienced person it really does seem that these other rendering engines are
> indeed also physically based and can also give the same scientifically accurate
> output that Radiance can (also perhaps not as easily parsable as Radiance
> results). (Assuming that the user doesn't purposely use biased rendering
> techniques)
>
> There seem to be features such as human eye image calibration, or falsecolours
> that are rarer to be found in other engines, but slowly I am seeing mentions of
> these features emerging.
>
> I also stumbled upon this comparison website:
>
> https://www.janwalter.org/RadianceVsYouNameIt/radiance_vs_younameit.html
>
> In that website, it is not obvious how the material and light properties were
> converted for each engine, but in short, the graphical outputs look the same.
>
> I hope that someone on this list can help explain to me in simpler terms what I
> am overlooking :)
>
> --
> Dion Moult
>
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