Am 22.01.2011 12:19, schrieb Mr:
> Hi,
> We are trying to implement partial output (border render) into blender's
> exporter.
> What happens is that we got it working except opening the output image crashes
> blender. I suppose it's due to this fact mentioned in povray doc:
>
> """
> When rendering a subset of *rows* (+sr/+er) POV-Ray writes the full height into
> the image file header and only writes those lines into the image that are
> rendered. This can cause problems with image reading programs that are not
> checking the file while reading and just read over the end.
>
> If POV-Ray wrote the actual height of the partial image into the image header
> there would be no way to continue the trace in a later run.
> """

As far as 3.7 is concerned, that section of the docs is actually 
outdated: POV-Ray will /always/ write a complete image, with pixels 
outside the rendered region filled with black. (This could be improved 
for images with alpha channel, as I think it would make more sense to 
set the "outside" pixels to all transparent there, but that's a 
different topic.)

So maybe you should first investigate what blender actually /expects/. I 
wouldn't be surprised if it would expect the rendered image to be 
trimmed to the rendered region's size, rather than padded.

While it would definitely be possible to add a switch to POV-Ray to 
change that behaviour, it doesn't make much sense to implement it right 
/now/: There are currently plans for certain internal changes to how 
POV-Ray buffers the output image during rendering, which will also 
affected the very same portions of code that would have to be modified 
for "your" feature; so chances are it won't be implemented before those 
planned changes.

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