Network ray tracing slabs?

Network ray tracing slabs?

Post by Jeff Garz » Sat, 16 Nov 1996 04:00:00



I looked around the FTP sites for a POV network renderer and couldn't
find a decent one, so I'm going to write one.  The only part I'm curious
about is picture slices.

POV allows a part of a picture to be specified and rendered, such as
rendering *just* the upper-left quadrant of a complex picture.

How does one put these slabs back together once they are rendered?

 
 
 

Network ray tracing slabs?

Post by Julius Valkenbur » Tue, 19 Nov 1996 04:00:00



> I looked around the FTP sites for a POV network renderer and couldn't
> find a decent one, so I'm going to write one.  The only part I'm curious
> about is picture slices.

> POV allows a part of a picture to be specified and rendered, such as
> rendering *just* the upper-left quadrant of a complex picture.

> How does one put these slabs back together once they are rendered?

Let's assume you use TGA output format.

If every slice consists of complete scanlines it easy, just strip of the 18 bytes TGA header of all slices
except the first one, concatenate al parts, et voila.

If a slice can be any rectangular subset of the whole picture, it's a bit more complicated. When you let
povray render a small 'window' of the final picture, it saves the result as a partial TGA, with complete
scanlines, but the parts of the scanlines that are not part of the rendered area are black.

You'd have to save the information about the size and positition of the rendered area, and use that to put the
pieces back together. It should be fairy easy to to, 'cause the TGA format is so simple, just an 18 bytes
header stating the size of the image, and then each scanline of the image, three bytes for each pixel.

I wrote a little program that allows you to concatenate separate slices of an image, and another one to insert
a rectangular subset of an image into another. If you're interested, let me know.



 
 
 

Network ray tracing slabs?

Post by Gary Pay » Fri, 22 Nov 1996 04:00:00



>> I looked around the FTP sites for a POV network renderer and couldn't
>> find a decent one, so I'm going to write one.  The only part I'm curious
>> about is picture slices.

I take it you have found the PVM version of POVRay 2? I haven't seen
version 3 as yet, but maybe someone is working on it. You CAN get PVM
to run under Windows, as well as UNIX (I can't remember the URL at
this time). This may be a better way to go, since its more of a
standard.

If you do go the DIY route balancing the loads on the processors can
be REALLY bad. You can end up with one processor waiting forever to
finish the most complex part of a scene. Either you need lots of small
slabs, or a better way of specifying a job which samples pixels over
the whole scene.

Either way, don't be scared to get down and dirty with the POVRay
source code, you get a better result and learn how POVRay works at the
same time.

Gary.

 
 
 

Network ray tracing slabs?

Post by Jeff Garzi » Fri, 22 Nov 1996 04:00:00




> >> I looked around the FTP sites for a POV network renderer and couldn't
> >> find a decent one, so I'm going to write one.  The only part I'm curious
> >> about is picture slices.
> I take it you have found the PVM version of POVRay 2? I haven't seen
> version 3 as yet, but maybe someone is working on it. You CAN get PVM
> to run under Windows, as well as UNIX (I can't remember the URL at
> this time). This may be a better way to go, since its more of a
> standard.

I should clarify myself a little bit more.  I am writing a simple batch
processor that divides up parts of a picture into pieces, sends each
piece off to be rendered by POV, and then composites the result into a
whole picture.  It is intended to be a network queue, where someone can
submit a .zip file with a POV 3 .ini file in it, and it will render the
scene or animation.

My program is very simple.  It avoids the [still considerable] overhead
of PVM-like network architectures, and instead goes with a less elegant
solution.

Yes, I did try PVM, but a test run with the current version of my net
batcher proved that my method is faster.  The only downside is that the
rendering is "unbalanced", but I use a number of hacks to guess a
network machine A1's speed, current load, and the complexity of the slab
to be rendered by A1.
--

Spinne, Inc.                        http://www.spinne.com/

   State-of-the-art efficient systems for the Internet.

 
 
 

Network ray tracing slabs?

Post by Kari Kivisa » Sun, 24 Nov 1996 04:00:00




>I haven't seen version 3 as yet, but maybe someone is working on it.

PVMPOV3: Distributed PovRay 3.0 by Cameron MacKinnon
http://www.interlog.com/~mackin/pvmpov3/

--
-----------------------------------------------------------------------
Kari Kivisalo                              http://www.hut.fi/~kkivisal/

 
 
 

1. ANNOUNCE(POV-Ray): Ray tracing of trimmed rational surfaces

 Hello,

  I would like to announce new unofficial version of POV-Ray 3.02. This version
extends latest POV-Ray by ability of ray tracing trimmed rational (bezier)
surface patches. In addition it renders current "bicubic_patch" nearly at same
speed as method from official POV-Ray 3.02 but it does not require big ammount
of precomputed data. You can download source code of this patch from:

     ftp://atrey.karlin.mff.cuni.cz/pub/local/0rfelyus/povray-3.02/

  There are also binaries for Linux and MS DOS(compiled with DJGPP v2). Please
send me your comments, advices or reminders. Also I would like to see beautiful
pictures which you render with this version.

Dan

ps: if you are interested in algorithm I use than look at: Tomoyuki Nishita,
Thomas W. Sederberg and Masanori Kakimoro: Ray Tracing Trimmed Ratinnal Surface
Patches [proceedengs of SIGGRAPH '90; Computer Graphics, vol 24, Num 4, August
1990]

2. Animation Program Wanted

3. POV-Ray and volume ray tracing?

4. Startup/compiling failure

5. Moray bundled with Ray Tracing Worlds with POV-Ray

6. *** Grand Open: News Service for 3D & Multimedia on 3Dup.com ***

7. FS: BOOK - Ray Tracing Worlds with POV-RAY (book+disks)

8. WANTED: canned edge detection routines/graphics libraries

9. Ray-z-Buffer Approach for Ray Tracing

10. Ray tracing: ray-object intersection

11. Ray-tracing using non linear ray...

12. Fastest way to generate eye rays in Ray Tracing

13. ANNOUNCE(POV-Ray): Ray tracing of trimmed rational surfaces