> "MichaelJF" <mi-### [at] t-onlinede> wrote:
>
>>
>> My first thought was to have a bigger container and multiple translated
>> densities within the media-statement, but the result was annoying too. A close
>> container seems to be necessary. I then merged the Containers and put multiple
>> densities inside (translated alike the containing boxes). May be more to the
>> intent of omniverse - and no scaling needed.
>>
>
> I ran MichaelJF's code example with one of the latest 64-bit 3.7.1 dev builds
> (v3.7.1-alpha.8927145+av352), with and without the enclosing hollow box.
>
> Without the box, I see NO speckles at all, even during an animation with the
> camear moving around. *With* the enclosing box, the speckles appear, as noted.
> But I tried something else-- eliminating that hollow box, and substituting a
> simple thin background box *behind* the scene instead-- just as a large
> background object. With that box in the scene, the speckles are still there. But
> *without* the box, no speckles. (I actually animated the box to get smaller--
> and as the edges of the box 'pass' the individual speckles (from the camera's
> view), they disappear one by one.)
>
> From this simple test, it *seems* that the speckles only appear when there is
> some kind of background surface behind the scene's media containers. I don't
> know if this helps with the problem, but it's interesting.
>
> By the way: In one of the code examples in this post, the camera is like this:
>
> camera {
>  location -4*x look_at 0
>  up y
>  right image_width/image_height*z // z instead of x
> }
>
> I assumed this was just another way of expressing 'handed-ness' in POV-Ray; but
> the results (compared to *x) are not what I expected; it actually creates a
> flipped mirror-image of the scene, left-to-right. (I tried this with a 'text'
> object, and the text is 'backwards.') I've never used *z there before, so I
> really don't know the reason for this.
>
> But here's the test scene, re-done, to show the speckles problem. Either run a
> 150-frame animation (clock 0 to 1), or just eliminate the background box, to see
> the difference.
>
> -----------
> #version 3.7; // or 3.71
>
> camera {
>  location -4*x look_at 0
>  up y
>  right image_width/image_height*z // should be *x
> }
>

What really mather is that the right vector to be perpendicular to the 
up vector, and it's relative length. Also, it should be perpendicular to 
the direction vector. Normally, those are right toward x, up toward y 
and direction toward z.
In the sample camera, direction and right are in the SAME direction, and 
it cause some problem.

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