Bob Hughes <inv### [at] aolcom> wrote in message
news:37e14074@news.povray.org...
> Hmmm, to view other camera angles reparsing is needed because of the
> change in rays going to/from objects.  Their profiles are always going
> to be different, well that's my guess anyhow.

So parsing is view angle-dependent, rather than just scene-dependent.

> Parsing was improved as
> I recall for multiple frames or renders of the same scene but think
> you're talking about keeping a memory map of sorts which considers any
> and all changes to camera position.  Of course if a scenes objects,
> etc. change with time then the question is probably moot.
>

My situation is a "fly through" where the camera location/angle change but the
scenes objects do not.

Thanks for the info,

-John VanZwieten

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I'm not totally inner workings savy, but yes, from what I understand
the visible scene is calculated so the other stuff can be dropped out.
That makes for a change in parse I believe even when just viewpoint
changes.

Bob

John VanZwieten <Joh### [at] emailmsncom> wrote in message
news:37e142da@news.povray.org...
>
> Bob Hughes <inv### [at] aolcom> wrote in message
> news:37e14074@news.povray.org...
> > Hmmm, to view other camera angles reparsing is needed because of
the
> > change in rays going to/from objects.  Their profiles are always
going
> > to be different, well that's my guess anyhow.
>
> So parsing is view angle-dependent, rather than just
scene-dependent.
>
> > Parsing was improved as
> > I recall for multiple frames or renders of the same scene but
think
> > you're talking about keeping a memory map of sorts which considers
any
> > and all changes to camera position.  Of course if a scenes
objects,
> > etc. change with time then the question is probably moot.
> >
>
> My situation is a "fly through" where the camera location/angle
change but the
> scenes objects do not.
>
> Thanks for the info,
>
> -John VanZwieten
>
>
>

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On Thu, 16 Sep 1999 14:23:55 -0500, Bob Hughes wrote:
>I'm not totally inner workings savy, but yes, from what I understand
>the visible scene is calculated so the other stuff can be dropped out.
>That makes for a change in parse I believe even when just viewpoint
>changes.

Nope.  But vista buffers are view-angle dependent.  Still, there's not
currently any way to save the results of the parse.  My understanding
is that it wouldn't save as much time as it might seem anyway.

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John VanZwieten wrote:
> 
> Is it necessary for POV-Ray to parse a file separately for each view of the
> same scene?  Is there any way to "save" the result of the parsing to use in
> repeated raytracings from different views?
> 
> Thanks in advance for any help with this.
> 
> -John VanZwieten

There is no simple way how to do this.
POV-Ray is an offline program which reads
its input, computes a pretty output and
terminates. There is an animation loop,
but it is based on reparsing the scene.

I noticed some debates on a binary format
(this is probably what you mean) but it
was never implemented (binary triangle 
meshes are the only exception). Anyway,
a binary format would not lead to a 
significant parsing speedup.

You asked for "any way". OK, there is a 
way how to do a camera animation without 
reparsing the scene. This requires some
programming. You have to write a program
which mimicks POV-Ray but keeps running
unless told to terminate. Such an 
interactive POV-Ray must have an option 
to parse a new file after rendering a
frame, without destroying the original
scene which is still in memory. The new 
file will contain just the new camera.
That's it.

	y.

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Ron Parker <par### [at] fwicom> wrote in message news:37e14498@news.povray.org...
> On Thu, 16 Sep 1999 14:23:55 -0500, Bob Hughes wrote:
> >I'm not totally inner workings savy, but yes, from what I understand
> >the visible scene is calculated so the other stuff can be dropped out.
> >That makes for a change in parse I believe even when just viewpoint
> >changes.
>
> Nope.  But vista buffers are view-angle dependent.  Still, there's not
> currently any way to save the results of the parse.  My understanding
> is that it wouldn't save as much time as it might seem anyway.

Why not?  Parsing on a scene I'm working with takes >1.5 hours.

-John Van

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On Thu, 16 Sep 1999 14:36:02 -0500, John VanZwieten wrote:
>
>Ron Parker <par### [at] fwicom> wrote in message news:37e14498@news.povray.org...
>> On Thu, 16 Sep 1999 14:23:55 -0500, Bob Hughes wrote:
>> >I'm not totally inner workings savy, but yes, from what I understand
>> >the visible scene is calculated so the other stuff can be dropped out.
>> >That makes for a change in parse I believe even when just viewpoint
>> >changes.
>>
>> Nope.  But vista buffers are view-angle dependent.  Still, there's not
>> currently any way to save the results of the parse.  My understanding
>> is that it wouldn't save as much time as it might seem anyway.
>
>Why not?  Parsing on a scene I'm working with takes >1.5 hours.

The reason that was given the last time this came up was that profiling
shows that most of the time parsing is actually spent allocating and
shuffling memory around.  Of course this isn't true for all scenes, but
that's what "they" said.

Now that I have access to a copy of vTune for Windows, maybe I'll find 
a big scene to parse and see for myself.

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In article <37e149fe@news.povray.org> , par### [at] fwicom (Ron Parker) wrote:

> The reason that was given the last time this came up was that profiling
> shows that most of the time parsing is actually spent allocating and
> shuffling memory around.  Of course this isn't true for all scenes, but
> that's what "they" said.
>
> Now that I have access to a copy of vTune for Windows, maybe I'll find
> a big scene to parse and see for myself.

You can try pyramid.pov in the sample scenes. Just increase the recursion
level if you need a scene taking even longer to parse.


    Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany

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But what when you render exactly the same scene at a different resolution?
Then it seems a pity that you have to render again.....

Sander

Bob Hughes <inv### [at] aolcom> schreef in berichtnieuws
37e143e8@news.povray.org...
> I'm not totally inner workings savy, but yes, from what I understand
> the visible scene is calculated so the other stuff can be dropped out.
> That makes for a change in parse I believe even when just viewpoint
> changes.
>
> Bob
>

Post a reply to this message

You might notice that renders (and parses) tend to be quicker when run
the second time.  This of course might be OS platform dependant and
such, don't know.  Possibly it's only because of memory use
effieciency of the OS and nothing to do with POV-Ray itself.

Bob

Sander <san### [at] the-internet> wrote in message
news:37e1573d@news.povray.org...
> But what when you render exactly the same scene at a different
resolution?
> Then it seems a pity that you have to render again.....
>
> Sander
>
> Bob Hughes <inv### [at] aolcom> schreef in berichtnieuws
> 37e143e8@news.povray.org...
> > I'm not totally inner workings savy, but yes, from what I
understand
> > the visible scene is calculated so the other stuff can be dropped
out.
> > That makes for a change in parse I believe even when just
viewpoint
> > changes.
> >
> > Bob
> >
>
>
>

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But skipping the parsing step would also remove the need for all of this
memory shuffling.  Once you've got a scene parsed and allocated in memory,
it would be nice to render scenes of an animation by simply changing what's
already in memory instead of destroying it all and rebuilding it for each
frame.

And, while it wouldn't make much difference for scenes with lots of glass or
media, it could be a noticable speed improvement for other scenes, such as
ones with lots of triangles or ones built using extreme recursion (which POV
is slow at parsing).

And, granted, all those light buffers, vista buffers, and the like would
have to be re-computed each time, but I still think it is something that
would benefit POV.

-Nathan

Ron Parker <par### [at] fwicom> wrote
> The reason that was given the last time this came up was that profiling
> shows that most of the time parsing is actually spent allocating and
> shuffling memory around.  Of course this isn't true for all scenes, but
> that's what "they" said.
>
> Now that I have access to a copy of vTune for Windows, maybe I'll find
> a big scene to parse and see for myself.

Post a reply to this message