clipka <ano### [at] anonymousorg> wrote:
>
> So the first observation is that we /should/ indeed see a (physically)
> linear gradient.
>
 So what the left height
> field actually shows is that
>
>      I(x)^(1/2.2) ~= x
>      I(x)         ~= x^2.2
>
> which is /wrong/.
>
>
> As for the shadowed side not being absolutely black, this is simply due
> to the default ambient value being non-zero. Try setting ambient_light
> to 0, or explicitly specifying ambient 0 in your texture.

Here is an amended version of the same test according to your suggestions.
Both height fields were created in 3.7. Ambient light in all cases was set to 0.

What I notice, however, in this new rendering is that the border between light
and shadow appears even more unnaturally abrupt. Your expertise in these
matters in absolutley astonishing (was all that off the top of your head?)
but maybe even you would admit that this picture, if someone did not know
what it was of, does not look like a cylinder, as the hf attests.
To my eye it almost looks like a band of white next to band of black.

I'm not really disputing but skeptical and trying to understand.
I've run into a related problem with this mysterious parabola before, where I
least expected to find it -- with so-called "linear perspective" where
it turns out, if you plot a graph of size to distance, you don't get
the famous Brunelleschi vanishing lines but a parabola instead. Which if you
think of a plane cutting through a cone makes sense.

Post a reply to this message

Attachments:
Download 'cylinder_3-6_3-7(2).png' (89 KB)

Preview of image 'cylinder_3-6_3-7(2).png'