I'm with you on this one. It's way too complicated. We know that Web users have little patience for forms with too many fields, pages that take a second too long to load, text that runs more than a couple sentences, and so on. Try to make them do a complex dance just to get past the bouncer at the door and they're likely to give up and go to a different club.

Agreed... The idea isn't bad, but this particular implementation is.

If the challenge of your captcha is parsing 3D images, there's no need to make the label letters a tiny unreadable magenta. In fact, you don't need letters at all -- this is merely an artifact of the "enter text for an image" structure of current captchas. It would be far better to have clickable target squares in the image, and just use JavaScript to ask the user to click on several targets in succession -- which is maybe even easier than text-based captchas. Using JavaScript has the additional advantage that it won't fit as well within existing captcha-forwarding spammer frameworks.

I'd happily take this over mass obnoxious in-your-face spamming any day.

The example is awkward but could be simplified as "click on the walking man's left arm", and if there were five images 150x150 side by side and only one image had the walking figure the spambot would have to choose the correct image and the correct 15x15 pixel range in that image, so a 1/500 chance of being right.