"tcgetattr" <tg### [at] getattrinvalid> wrote in message 
news:4aeae4a5@news.povray.org...
> tcgetattr wrote:
>> Hello.
>>
>> I've got a bunch of satellit pictures like this one
>> http://foo.buvette.org/trucs/nuages.jpeg and I want
>> use them to make an animation of the earth.
>>
>> How can I process this pics to make them usable as
>> an image_map ?
>
> I think that i need this sort of pictures :
> http://earthobservatory.nasa.gov/Features/BlueMarble/BlueMarble_monthlies.php

There are some immediate problems apparent with this that could make life a 
little complicated. I'll just start throwing a couple of ideas in the air to 
get things started:

The cloud image you have only covers a small part of the planet whereas the 
BlueMarble images cover the whole planet, so, unless you have images from 
other multiple geostationary positions (or unless it's not stationary) then 
you can't cover the entire globe. If you do have other images then you have 
the problem of mosaic'ing them together.

Mapping the cloud cover image precisely to the projection of the BlueMarble 
images is likely to be tricky (if you need to do that). You may be able to 
get something approximate by using your cloud images with a flat projection 
onto a sphere and then using a spherical camera in the middle of the sphere 
to generate an image that would approximately overlay the BlueMarble images. 
If you want to overlay the clouds onto the BlueMarble images you could 
probably achieve this with a single pass in POV-Ray by using a spherical 
projection to project a BlueMarble image onto a slightly larger sphere that 
would show up as being behind the cloud sphere when the camera is in the 
middle of the two concentric spheres.

You could maybe use a filter on the image to  make the darker green parts 
transparent so that you could overlay the image onto a BlueMarble image (if 
you need to overlay the images). This could be done in an external graphics 
editor (e.g. Photoshop). If you wish to add tranparency that POV-Ray can use 
then you'll probably need to convert the cloud images into one of the 
formats that the filter option on the image_map supports (e.g. png or gif).

Regards,
Chris B.

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