Hi all,

I have been working on another ray-traced optical illusion. Attached is the
current version, which I consider nearly done. I have only a few more finishing
touches planned. Nevertheless, although I cannot quite put my finger on it, I am
not yet entirely happy with the overall composition. So your thoughts on the
image sofar and suggestions for improvement are most welcome, especially quick
wins! :-)

Technical details and credits: No post-processing has taken place on the image
to make the illusion work. This is the 3D scene as it is rendered by POVRay. The
grass is made using macros by Gilles Tran. The palm tree is made using the tree
macro by Tom Aust, modified by Gena Obukhov. The chains are made using a macro
by the PM 2Ring, using catenary calculations by Zdislav Kovarik.

Cheers,
Erwin

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Attachments:
Download 'touristtrap-0_7.jpg' (163 KB)

Preview of image 'touristtrap-0_7.jpg'

This is impressive. Although I can see the transition point, I can't 
figure out how you got the projection and lighting to match up. (It 
looks orthographic, but there's a horizon.)

  - Slime

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> This is impressive.

Thanks :-)

> Although I can see the transition point, I can't
> figure out how you got the projection and lighting to match up. (It
> looks orthographic, but there's a horizon.)

I have used a combination of tricks to make the illusion work. Each helps to
obfuscate the others, so it is indeed not obvious how the image is created. I
don't plan to reveal these tricks though. I believe the image is more intriguing
without the mystery behind the illusion being revealed.

I am happy to share all non-illusion related details of the scene though, should
anyone be interested (e.g. macros for generating the path, for placing the
grass, etc). These are fairly mundane though, so I am not sure if anyone cares.

Cheers,
Erwin

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This is an epic piece of work, both in imaginative concept and execution.

I would say however to pick (after giving you 20-20-20), that my eyes did clue
into something "wrong" with the color / shadows as the image sat loaded in my
browser with only the top half visible.

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"gregjohn" <pte### [at] yahoocom> wrote:
> This is an epic piece of work, both in imaginative concept and execution.

Thanks! Given the time and effort such an image requires, it's always nice to
receive positive feedback of course.

> I would say however to pick (after giving you 20-20-20), that my eyes did clue
> into something "wrong" with the color / shadows as the image sat loaded in my
> browser with only the top half visible.

Thanks for the suggestion. I think I know what you mean. I changed some of the
ambient settings and changed the direction of the light, and it should look
better now. At least, I think it does. I have attached the final image so you
can Judge for yourself. As you can see, I also made some changes to the tower to
make its style more uniform.

Cheers,
Erwin

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Attachments:
Download 'touristtrap-1_0.jpg' (165 KB)

Preview of image 'touristtrap-1_0.jpg'

Picking again, the problem I think is with the left edge. In perspective this
narrow rectangular solid has a left face and right face.  The left face should
have the same color as the main part of building at TOP. The right face should
have the same color as the main part of building at BOTTOM.   You appear to have
made a gradient that does this to some degree, but it's too weak.

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"gregjohn" <pte### [at] yahoocom> wrote:
> Picking again, the problem I think is with the left edge. In perspective this
> narrow rectangular solid has a left face and right face.  The left face should
> have the same color as the main part of building at TOP. The right face should
> have the same color as the main part of building at BOTTOM.   You appear to have
> made a gradient that does this to some degree, but it's too weak.

The reason for the color difference is that it's a different material. I can
make the texture of the left and right edges the same as the rest of the tower,
and the colors will then match up nicely. See the attached image. However, I do
not like this, because it results in an awkward transition at the place where
the orientation of the edge changes from being perpendicular to the wall (at the
top) to being parallel to it (at the bottom). With a different (darker) texture,
the transition is still there, but less distracting, so I prefer that. I like to
hear your thoughts though.

Cheers,
Erwin

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Attachments:
Download 'touristtrap-1_0b.jpg' (165 KB)

Preview of image 'touristtrap-1_0b.jpg'

The part that sticks out to me is the direction of the light/shadows.  The
structure has the light on the left and shadows on the right, however, on the
tree, grass & fence posts the light is on the right w/ shadows to the left.

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"gonzo" <rgo### [at] lansetcom> wrote:
> The part that sticks out to me is the direction of the light/shadows.  The
> structure has the light on the left and shadows on the right, however, on the
> tree, grass & fence posts the light is on the right w/ shadows to the left.

At the top of the picture the light indeed comes from the left, whereas at the
bottom (including the bottom part of the tower) it comes from the right. This is
necessary to keep the main tower walls consistently lit despite their apparent
change in orientation going from top to bottom. Fellow ray-tracers may spot this
immediately and even find it distracting. Most people hardly seem to notice it
though :-)

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