Hi Tsjerk,
Ok, yes, I see your point now. I was unaware of the memory aspects not being helped by the rendering in parts, so I did not catch the deliberate redirection you had done! However, Tom's method would be able to avoid the too large memory issue since if the viewport only 'saw' one little piece at a time and worked on that independently of the rest of the scene (essentially unaware if there is one more tile or a hundred more...) But there are the multiple perspective limitations, etc.
Thanks for clarifying the 'under the hood' part for me and sorry to have then added my own assumptions to the mix!! (as I worried about in my last paragraph!)
-Seth

On Sat, Oct 24, 2009 at 2:41 AM, Tsjerk Wassenaar <tsjerkw@gmail.com> wrote:
Hi Seth,

Rendering in parts does not avoid taking the whole scene in memory.
That is a more important obstacle than the size of the image. That is
why Warren suggested using the hash_max setting, which will alleviate
the memory dependence of the ray tracing, avoiding crashing. The
raytracing in parts that POV ray offers is not about saving memory; a
scene that is too complex to load will still break. It's about CPU
efficiency: you can distribute the calculation over multiple CPUs.
This was particularly important for POV Ray versions <= 3.6 (3.7 will
be able to use multiple CPUs). Also, there's nothing mathematically
tricky about what POV Ray does for partial ray tracing: it only traces
the rays that belong to pixels you want to have rendered. E.g. it will
write a 9000x6000 pixel image (according to the header), but only have
part of the image filled in.

Maybe you can see that I wasn't so much missing the point, or maybe
was deliberately trying to miss it, since it builds on misconception
of what is under the hood. If you want to connect withe the
capabilities that POV ray offers in that regard, which may have some
merits, you may want to suggest Warren to implement partial
renderings, adding startrow, endrow, startcolumn and endcolumn to the
ray command. That might be handy when using pymol for raytracing
scriptwise on a cluster. But you'll be disappointed if you expect it
will keep your scene from crashing Pymol (but then there's the
hash_setting...).

I hope this clarifies things a bit.

Cheers,

Tsjerk

On Sat, Oct 24, 2009 at 8:21 AM, Seth Harris <seth00@gmail.com> wrote:
> Tsjerk,
> I think you are missing the point of Tom's post, which was a suggestion to
> aid someone who's computer could NOT deliver the image in "as high a
> rsolution as you want', so Tom was proposing a way to break the image down
> into bite-size chunks that the computer COULD then handle. So the suggestion
> was to take one scene desired at 9000x6000 which would make the computer
> crash and instead mathematically figure the necessary transpositions to
> render it in tiles such as upper left quadrant, upper right, etc. each at
> 4500x3000 or whatever the computer could handle (and then you could put them
> all back together in photoshop, e.g.). So for someone with deep coding
> skills they could likely teach pymol to ray just the segments they wanted
> and deal with the overall perspective of the whole scene, but for a hack
> like myself I'd likely start the work around of trying to figure out the
> camera position and where I'd have to put it to get just a quarter of the
> scene at a time in the viewport (or an eighth, or whatever). As Warren said,
> you'd likely have to set orthoscopic to get rid of the perspective for
> starters (at least in the hack approach, but there would be more direct
> better ways for the skilled).
>
> As a side point, Povray (if I remember correctly)  in fact allows you to
> break a large rendering job up into tiles pretty much just like Tom
> suggests, so not so crazy of an idea! I think in that case you can specify
> starting and ending x,y pixel coordinates from your large scene. But not in
> Pymol as far as I know.
>
> Sorry if I've now gone stepping in and misinterpreting someone's points
> myself, but it seemed like there was a lot of cross-purpose talk either from
> assumptions or extra politeness!
>
> -Seth
>>
>> > The requested size is 20" by 30". I calculated that it would
>> > correspond
>> > to a 6000 x 9000 pixel image.
>> > How can I create such a large ray traced image without crashing the
>> > computer?
>>
>>
>> Message: 2
>> Date: Fri, 23 Oct 2009 11:27:47 +0200
>> From: Tsjerk Wassenaar <tsjerkw@gmail.com>
>> Subject: Re: [PyMOL] Saving high resolution images
>> To: Thomas Stout <tstout@exelixis.com>
>> Cc: pymol-users@lists.sourceforge.net
>> Message-ID:
>>        <8ff898150910230227k12719cedv8656233c7e67d361@mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Hi Thomas,
>>
>> You can also zoom out to get everything in view. You can also change
>> the field of view. And then you can ray just the way you want, based
>> on what you have in sight, in as high a resolution you want.
>>
>> Cheers,
>>
>> Tsjerk
>>
>> On Thu, Oct 22, 2009 at 9:35 PM, Thomas Stout <tstout@exelixis.com> wrote:
>> >
>> > But isn't it true that only the objects that are visible in the viewport
>> > are what are written to the rendered image file? ?I was proposing rendering
>> > a poster-sized image in "tiles" and stitching them back together post facto
>> > to create a very large, high resolution image.
>> >
>> > something like:
>> > -----------------------
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | render 1 | render 2 |
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > |----------------------
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | render 3 | render 4 |
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > | ? ? ? ? ?| ? ? ? ? ?|
>> > -----------------------
>> >
>> > I feel like I'm missing something important here!
>> > -Tom
>> >
>> > -----Original Message-----
>> > From: Tsjerk Wassenaar [mailto:tsjerkw@gmail.com]
>> > Sent: Thursday, October 22, 2009 11:45 AM
>> > To: Thomas Stout
>> > Cc: pymol-users@lists.sourceforge.net
>> > Subject: Re: [PyMOL] Saving high resolution images
>> >
>> > Hi Thomas,
>> >
>> > The viewport is not important for rendering. You can render at whatever
>> > resolution/dimensions you want with whatever viewport. You can even make a
>> > panorama using a wide angle lens if you want to have something for on your
>> > wall ;)
>> >
>> > Cheers,
>> >
>> > Tsjerk
>> >
>> > On Wed, Oct 21, 2009 at 11:43 PM, Thomas Stout <tstout@exelixis.com>
>> > wrote:
>> >>
>> >>
>> >> Here's a crazy idea: ?if someone out there were clever at both python
>> >> and manipulating orientation matrices, I would bet that a "scene"
>> >> could be quartered or cut into eighths and "translated" such that each
>> >> portion filled the viewport for rendering; then the individual images
>> >> could be spliced back together in one's favorite image handling
>> >> program a la panoramas in photography.... ?Is this way too complex to
>> >> be bothered with? ?I suspect parallax may be a problem...
>> >>
>> >> -Tom
>> >>
>> >>
>> >>
>> >> -----Original Message-----
>> >> From: Eva Vanamee [mailto:Eva.Vanamee@mssm.edu]
>> >> Sent: Monday, October 19, 2009 1:51 PM
>> >> To: pymol-users@lists.sourceforge.net
>> >> Subject: [PyMOL] Saving high resolution images
>> >>
>> >> Hi,
>> >>
>> >> I'd like to save an image in high resolution for a poster.
>> >> The requested size is 20" by 30". I calculated that it would
>> >> correspond to a 6000 x 9000 pixel image.
>> >> How can I create such a large ray traced image without crashing the
>> >> computer?
>> >> Many thanks in advance for the help.
>> >>
>> >> Best,
>> >>
>> >> - Eva
>> >>
>> >>
>> >> ----------------------------------------------------------------------
>>
>
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--
Tsjerk A. Wassenaar, Ph.D.
Junior UD (post-doc)
Biomolecular NMR, Bijvoet Center
Utrecht University
Padualaan 8
3584 CH Utrecht
The Netherlands
P: +31-30-2539931
F: +31-30-2537623