On 5/5/24 06:07, kurtz le pirate wrote:
> Without changing the value of max_gradient (3e10) and just by adding the
> min() in my function, POV finds say : "The maximum gradient found was
>   4235539.500, but max_gradient of the isosurface was set to
> 30000001024.000...".

Alright. Though, that feels to me like too large a max gradient for the 
min() approach! Let me try quickly here.

A truth with isosurface{}s, is that setting higher gradients tends to 
find higher gradients. A reason is often rays glancing off, or just 
catching, the far edges of shapes.

Another truth is that max gradients seen are not constant with respect 
to incoming rays.

---
At 10 (Which for me looks OK. See attached image) I see:

The maximum gradient found was 13.001, but max_gradient of the 
isosurface was set to 10.000. ...

---
At 1e5 (I don't have the patience for more on my little i3) I see:

The maximum gradient found was 18.814, but max_gradient of the 
isosurface was set to 100000.000. ...

I'm unsure what's happening with your version of the scene to see the 
much larger max gradient with min(). Maybe your bounding box is much 
larger than it need be? I don't know.

I'm attaching my version of the scene. I used yuqk, but I don't think 
I've changed anything in the solver which would account for difference 
in max gradients seen.

Do you see differences between your scene and mine which might account 
for the difference in max gradients? I'm willing to do the digging, if 
you'll post your version of the scene. I'd like to understand what I'm 
missing.

Bill P.

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Preview of image 'tmp.png'