Warp <war### [at] tagpovrayorg> wrote:

> > As the horizontal image width (in POV units) as
> > camera_distance*tan(angle/2), a sphere with a radius of 3396.2 units
> > (the planet Mars) should exactly fit into the camera window when viewed
> > from a distance of 9330.982812 units - but instead the planet's disc is
> > still too large for the image (see attachment)!
>
>   Did you take into account perspective? You are not using a disc, but a
> sphere, and perspective will make the half of the sphere closer to the
> camera be larger than the "disc" at that exact distance.
>
>   You should try it with a true disc object instead.

I don't think the spherical shape would have *that much* of an effect. In my
(somewhat little) experience with POV cameras, the camera's direction vector
also has a bearing on the field of view.

The docs (3.3.1 Camera) says for the camera type: perspective, default values
are:

angle : ~67.380 (direction_length=0.5*right_length/tan(angle/2))
direction : <0,0,1>
right : 1.33*x

So you might need to play around with reducing the direction vector, and/or
taking care in the order you specify the parameters (yes, it can have an effect
too!). If you _are_ specifying the direction, try it without, or make sure it's
a vector of length 1 (unit vector), and comes before angle but after location.


Hope this helps

- sooperFoX

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