William F Pokorny <ano### [at] anonymousorg> wrote:
> On 2/19/26 07:05, Bald Eagle wrote:
> > Any ideas?
>
> Guesses.
>
> Some of what I see in your image can happen when the plane of the camera
> slices into shapes like the torus{}.
>
> That 'emission 1' didn't help much and that you have some apparent
> speckling looks more like solver issues - which could be related to
> geometry of the scene for the image posted and/or the state of the
> 'solver code' itself.

Could be.
The other weird thing is that the yellow torus was not only speckled - but it
was partially transparent as well.
I've seen and mentioned this before in other scenes.

>
> Are you using an orthographic camera?
>
> With the camera set up you have, how are you zooming?

Yes.  Luckily I emailed myself the scene, so I can reference it.

#declare Zoom = 0.4;
camera {
orthographic
location <IR*1.5, 0, -2*IR>
location <IR, 5*M, -2*IR>
//location <IR, 5*M, 0>
right    x*image_width/Zoom
up       y*image_height/Zoom
look_at <IR, 0, 0>
}

>
> Have you tried with both 'sturm' and not? If so, are there differences
> in result?

I didn't yet - but have thought about doing so.

>
> A wilder guess. The ray->surface intersection equations for the torus
> adjust each rays origin prior to creating the equation for the
> solver(s). The origin adjustments are unrolled after roots are found so
> as to get the real intersection positions. It's known that ray origin
> adjustment works less well at larger torus dimensions once the equation
> origin is beyond the first surface.

It's a 150-unit torus.

#declare M = 150;
#declare m = 20;

.....

torus {M, m pigment {rgb 1} translate T_Center}

I'll try perspective and maybe sturm when I get back in.
The really puzzling thing about it, is that all of the other tori render just
fine.

- BE

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