> Clipka has wrote:
>
> Without the `direction`, POV-Ray has no idea whether you want a
> left-handed or right-handed coordinate system.
>
> Remember, the `look_at` mechanism works as follows:
>
> (1) POV-Ray first sets up the camera as specified by your `up`, `right`
> and `direction` vectors, as if the `look_at` statement wasn't there.
> This defines the handedness of the coordinate system, the aspect ratio,
> and (depending on camera projection) the zoom (unless you also specify
> `angle`).
>
> (2) Once that is done, POV-Ray re-orients the camera (rotating it around
> its location) in such a manner that the `look_at` point is in the center
> of the image (for most projections at any rate).
>
> So specifying `look_at` is no replacement for specifying `direction`.

Thank you for your answer. I have learned something new with your message :-D.
In fact, most of my knowledge related to POVRay come from the following site :
http://users.skynet.be/bs936509/povfr/index.htm

In this site, they explain lot of things, and even if it is based on POVRay 3.6
it is still relevant but there is no sign of what you explain about the camera
in the appropriate section :-(. And there's nothing about radiosity...
By the way... I'm looking for a tutorial that explains in details how radiosity
works (Or is it to complicated ?). My current skills with the radiosity are the
following:
I render a radiosity scene in two pass, a first render with something like :
+W80
+H50
+RFO
+RF"radio_samp.rad"
Output_To_File=Off
Display=Off

Then a render with
+Wfinal width and +Hfinal height
+RFI
+RF"radio_samp.rad"

Of course, I save lot of time by doing this. I don't know much more about
radiosity and I'd like to know the details of this technique :-D.

Thank you.

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