Hello all,

I have some questions regarding large renderings.
(I'm using the command line version of povray for
linux/unix.)

1) Lets say I have a target size of some 10thousand
pixels height and width, like 40000x30000 pixels.
And I only want to render a part of it at a time
so I can handle the resulting images easier. I can
specify the wanted start/end-row and start/end-column
but povray still creates a image of the *whole* size
with only the rendered part in it. How can I avoid this
and make povray create an image only of the size of the
wanted part? I didn't find an appropriate command line
switch.
Of course I still can cut out the resulting part with
an image manipulation tool, but...

2) When specifying a region in the image, is the first
line called 1 or 0? The man page again doesnt say some-
thing about this. So e.g. if I want to render the first
400 columns, should I specify "+SC0 +EC399" or "+SC1 +EC400"?

3) Is there any limitation to the size of the resulting image?
Part of the image or the whole image?

Thanks and regards,
Leander

Post a reply to this message

"Leander" <nomail@nomail> wrote:
> 2) The man page again doesnt say some-
> thing about this.

Of course not. That is why there is a whole user manual included with
POV-Ray! You may want to read it.

In the online version the answer to all your questions is at:
<http://www.povray.org/documentation/view/3.6.1/217/>

Post a reply to this message

Leander wrote:
> [...]How can I avoid this
> and make povray create an image only of the size of the
> wanted part? I didn't find an appropriate command line
> switch.

There isn't.

The partial images are usable though - i once wrote a small shell script 
that extracts a selected part from such an image:

http://www.imagico.de/pov/img_crop.sh

> 
> 3) Is there any limitation to the size of the resulting image?
> Part of the image or the whole image?

You should turn off display of course but apart from that - no*.  Except 
of course limitations of the file system concerning file size and size 
limits of the image file formats.

*) up to the usual numerical limits of 32bit integers (2.1 billion)

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 14 Mar. 2006)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

Post a reply to this message

Leander wrote:
  > 1) Lets say I have a target size of some 10thousand
> pixels height and width, like 40000x30000 pixels.

40000x30000 is 1.2 billion pixels.  As a 24-bit uncompressed bitmap, 
that would take 3.6 gig of storage.

Certainly the largest image I'd ever come across.

-DJ

Post a reply to this message

> 1) Lets say I have a target size of some 10thousand
> pixels height and width, like 40000x30000 pixels.
> And I only want to render a part of it at a time
> so I can handle the resulting images easier. I can
> specify the wanted start/end-row and start/end-column
> but povray still creates a image of the *whole* size
> with only the rendered part in it. How can I avoid this
> and make povray create an image only of the size of the
> wanted part? I didn't find an appropriate command line
> switch.
> Of course I still can cut out the resulting part with
> an image manipulation tool, but...

The way PovRay handles this is a matter of contention, I for
one an often frustrated by the approach taken. I regularly
(at least in the past) render these sizes and often in strips.
The way it used to work was that while PovRay created a file
with the final dimensions, the actual image data was only the
piece you asked for. Very annoying since this is an illegal
image. One of the ways I used to get around this was to save
as TGA and write mmy own code that joined the bits together,
ignoring the file size header information.

Let me know if this has changed, ie: the image is now black
or equivalent except for the piece requested.

> 2) When specifying a region in the image, is the first
> line called 1 or 0? The man page again doesnt say some-
> thing about this. So e.g. if I want to render the first
> 400 columns, should I specify "+SC0 +EC399" or "+SC1 +EC400"?

0 to 399 I believe.

> 3) Is there any limitation to the size of the resulting image?
> Part of the image or the whole image?

I believe you are limited to 32bit ints for each dimension, haven't
tried to test this though.

-- 
Paul Bourke
pdb(NOSPAM)swin.edu.au

Post a reply to this message

DJ Wiza schrieb:
> Leander wrote:
>   > 1) Lets say I have a target size of some 10thousand
>> pixels height and width, like 40000x30000 pixels.
> 
> 40000x30000 is 1.2 billion pixels.  As a 24-bit uncompressed bitmap, 
> that would take 3.6 gig of storage.
> 
> Certainly the largest image I'd ever come across.

Just visit 
http://earthobservatory.nasa.gov/Newsroom/BlueMarble/BlueMarble_monthlies.html 
and download 86400x43200 RGB images with 3.7 billion pixels :-)

-- 

mat### [at] matweide
http://www.matwei.de

Post a reply to this message