message de news:3f8ad0f5$1@news.povray.org...
> calculations are unneeded; POV-Ray just wraps the image map around my
> airplane fuselage cylinder and then creates a "hole" wherever a light ray
> strikes a transparent pixel in the alpha channel of the image map... is
that
> a fair approximation of what's happening?

Other people will explain the details, but differencing many objects from a
main one is not very efficient and leads to long render times. The trick is
to cut the object in several pieces, have 1 or 2 difference per piece and
then union{} the pieces. Of course, this is not always possible but any
repeating objects such as windows should be treated that way whenever
possible.

> (2) Here's something I really don't understand: Obviously the trade-off of
> *exactly* the same as when I was using a 1000x1000 PNG file. The amount of
> memory used jumped considerably, of course, but the average rendering time
> between the 1000x1000 and 4000x4000 image maps was essentially unchanged.
Is
> that about right?

Experience shows that image_maps are very efficient so it's not really
surprising. The worse that can happen is RAM trouble.
About the jaggies, did you try interpolate 2 on the maps ? It can help
sometimes.

G.

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