"How Camp" <hac### [at] gmailcom> wrote:
> "stevenvh" <nomail@nomail> wrote:
> > This should not be too hard, and the change is limited to saving. (It doesn't
> > involve the render engine, for instance.)
>
> It appears more problematic than you suggest.  As the documentation reflects
> (and Wolf mentioned above):
>
> "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." (3.1.2.2.2)
>
> This behavior was a deliberate choice.  Not that this means the behavior
> shouldn't be reconsidered, just that it isn't arbitrary or accidental.

I guess you're right.
For PNG (and other formats that support it) the alpha channel could be used to
indicate which areas have been rendered. This also makes sense if you look at
the partial image as a common one: the rendered area is opaque, while the rest
of the image would appear transparent.
Alternatively, can't the information be included in the image's metadata. Again,
this may not be a solution for every image format.

Steven

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