Hi all,

Attached is my latest render of an impossible object. Out of the impossible
scenes I have rendered sofar, this one was the least challenging. There was
hardly any need for fancy tricks. Nevertheless, hopefully the resulting image is
still interesting. The grass is made using a texture created by Rune Johansen
(http://runevision.com). Comments and feedback are welcome, as always.

Cheers,
Erwin

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Attachments:
Download 'failure-1_00.jpg' (251 KB)

Preview of image 'failure-1_00.jpg'

Very nice, doesn't look like a failure at all ;)

The shadow on the inner right side of the monument doesn't
seem to match either light orientation. Is that an artefact
of the few fancy tricks you did use?

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Very nice indeed.

There is something about the shadows that need more work though, to make 
this even more convincing, in particular the left hand column.

Thomas

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Christian Froeschlin <chr### [at] chrfrde> wrote:
> Very nice, doesn't look like a failure at all ;)

Thanks.

> The shadow on the inner right side of the monument doesn't
> seem to match either light orientation. Is that an artefact
> of the few fancy tricks you did use?

It is an intentional artifact, intended to look at least at first glance fairly
okay. The problem is that the shadows cannot be entirely consistent because of
the two interpretations of the plane on which the shadow is cast (being nearby
at the top, and far at the bottom). The correct angle of the shadow would be to
match that of the shadow above it, but that would look wrong as well.
Alternatively, I could let the shadow of the front column extend all the way to
the top, but that would look strange as well. The front square pillar should not
be casting a shadow on the back one, given the direction of the light.

Hmm, I could change the alignment of _both_ shadows of the top bar such that
they align. Although still not correct, it may look somewhat better. See the
attached image. Does this look better?

Cheers,
Erwin

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Attachments:
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Preview of image 'failure-variant1.jpg'

Thomas de Groot <tenDOTlnDOTretniATtoorgedDOTt> wrote:
> Very nice indeed.

Thanks.

> There is something about the shadows that need more work though, to make
> this even more convincing, in particular the left hand column.

Okay, assuming you did not mean the shadow cast by the column, but the shading
of the column itself, I spent some time trying to improve this. Attached is an
updated image. I also changed the shading of the right hand column, while I was
at it. Although the difference is fairly subtle, I think it's an improvement.
Hopefully you agree. Anyway, thanks for the suggestion.

Cheers,
Erwin

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Attachments:
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Preview of image 'failure-variant2.jpg'

Eriban wrote:

> Hmm, I could change the alignment of _both_ shadows of the top bar such that
> they align. Although still not correct, it may look somewhat better. See the
> attached image. Does this look better?

I think it doesn't make a lot of difference. What I would expect
to see is just a thin shadow as it would have been cast by the leftmost
column were the object not impossible (I think this is also what Thomas
meant). Gimped version attached for clarity.

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Attachments:
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Preview of image 'failure-1_00.jpg'

Christian Froeschlin <chr### [at] chrfrde> wrote:
> I think it doesn't make a lot of difference. What I would expect
> to see is just a thin shadow as it would have been cast by the leftmost
> column were the object not impossible (I think this is also what Thomas
> meant). Gimped version attached for clarity.

Ah, I understand now. That gimped version finally caused the coin to drop.
Thanks. And yes, in retrospect, that's probably what Thomas meant as well. I had
been trying to fake a shadow of the horizontal top bar, as to me that seemed to
be the most correct, but apparently it did not work very well. It was only
confusing. So I assume the attached image is more to your liking?

Cheers,
Erwin

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Attachments:
Download 'failure-variant3.jpg' (309 KB)

Preview of image 'failure-variant3.jpg'

Eriban wrote:

> So I assume the attached image is more to your liking?

Yes ;)

BTW the shadows are very hard and dark. If the tricks still
work with area light and radiosity you could try these too.

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On 21-8-2011 21:35, Eriban wrote:
> Ah, I understand now. That gimped version finally caused the coin to drop.
> Thanks. And yes, in retrospect, that's probably what Thomas meant as well. I had
> been trying to fake a shadow of the horizontal top bar, as to me that seemed to
> be the most correct, but apparently it did not work very well. It was only
> confusing. So I assume the attached image is more to your liking?
>

Yes, sir! You got it right this time :-)

Shouldn't the shadow of the construction touch also the grass, maybe the 
trees? It is tall enough for that it seems.

Thomas

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"Eriban" <pov### [at] spamgourmetcom> wrote:
> Hi all,...
>  Nevertheless, hopefully the resulting image is
> still interesting.
....
> Cheers,
> Erwin

Being a great Escher fan, I love it. One idea did occur to me that I'd like to
share. Many of Escher's illusions worked all the better for the fact that the
images were either monochromatic or rendered in a limited color palette. The
bright blue background, although appealing for such a scenic image generally,
may be wowrking against the illusion. The high-contrast diagonal between the
land and sea cuts right across the bit where the "trick" occurs and tends to
focus the viewer's attention just in the wrong spot.  As the various landscaping
elements used in the land area are quite attractive, why not use them for the
entire background and allow the illusion bit to blend in? Just a thought - great
image either way.

Best Regards,
Mike C.

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