[Radiance-general] Re: Horizontal artifacts in large image

[Mark Stock]

The process ran straight through, with no pauses or restarts.

Another process (another third of the final image), which did
require a few restarts, is here:

http://mark.technolope.org/image/p21c_fish_take_3/redo_smooth_6/timg10_2_tw.jpg

This one contains the same horizontal bands, one at ~35% of the way
down, but a pair at about 85%.

But there's also a weird slightly-darker band 20% of the way down,
and on the center vertical tube.

I'm also noticing thin dark lines on some of the tubes. I marked
them in the following image:

http://mark.technolope.org/image/p21c_fish_take_3/redo_smooth_6/timg10_2_twm.jpg

Sorry about the long URLs. I'd move it to a more root-ward directory,
but stuff has been rendering constantly for 2+ weeks.

----
Georg writes:
You appear to have plenty of disk space, so I'd recommend to
use an ambient file. You may want to play with the ambient
resolution as well if you do this, to keep the size of that
file under control.
----

That's the way I would have done it in the first place, but
once the scene and the ambient file got up to 1.3 GB in RAM
(where I have only 1 GB), it started to thrash, and I'd only
made it to the 4k x 2k version by then. Plus, there were
still splotches from the not-completely-resolved ambient
distribution. Ultimately, with -aa 0, I get a smoother final
rendering, at the cost of a more speckled pre-filtered
rendering.

I'm trying a lower-resolution run right now. Thanks for
the input.

Mark


On Tue, 24 Jun 2003, Greg Ward wrote:
>
> Did you have to restart this rendering process?  The artifacts don't
> _quite_ look like an ambient calculation restart.  I have a competing
> theory, which is that a long integer is getting wrapped in the source
> testing code.  This is really a bug, but I guess it hasn't shown up
> before because no one has testing a light source 2^31 times in a single
> run.  Actually, maybe they have, but just never noticed the problem.
>
> I'll work on a fix for this today, but obviously you're going to have
> to find another way to repair your image to meet your deadline.  Sorry
> about that.  I recommend using the -vl option to rpict and rerendering
> a portion of your image to cover up the problem areas using pcompos.
> Let me know if you need help on figuring these options out.
>
> -Greg
>
> > From: Mark Stock <mstock@umich.edu>
> >
> > Fellow Radiance users,
> >
> > I recently completed a large image (1.4 GB .pic file, 16k
> > by 24k pixels), and it appears like there are two obvious
> > horizontal bands of incorrect values (one 30% from the top,
> > the other ~80% from the top). I pfilt'd the image down to
> > 5% of it's original size to make the image below:
> >
> > http://mark.technolope.org/image/p21c_fish_take_3/redo_smooth_6/
> > timg10_1_tw.jpg
> >
> > The commands that I ran were:
> >
> > rpict -x 16000 -y 24000 -vta -vp 0.2 0.2 -0.01 -vd 0.454 0.891 -0.08
> > -vu 0 0 1 -vh 58.66667 -vv 88 -ab 1 -aa 0 -ad 16 -as 0 -dv -ds 0.1
> > -dj 1.0 -t 600 -o img10_1.pic real.oct
> >
> > pfilt -1 -x /10 -y /10 -r 0.4 img10_1.pic > timg10_1_t.pic
> > pfilt -1 -e +3 -x /2 -y /2 timg10_1_t.pic | ra_ppm | cjpeg -q 95 >
> > timg10_1_tw.jpg
> >
> > Does anyone know where these artifacts originate, or how to
> > prevent them from appearing? I'm running the same image at
> > reduced resolution right now, but final print quality is
> > not going to be as I'd hoped.
> >
> > Mark
>
> _______________________________________________
> Radiance-general mailing list
> Radiance-general@radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>