Rosetta Comet Update Aug. 10 – See It In Cross-eyed Stereo

Two pictures of comet 67P/Churyumov-Gerasimenko taken two days apart. Sit back about a foot (0.3-meter) from the screen and slowly cross your eyes until you see the third stereo image appear between the two. Careful not to fall in any holes! Click to enlarge. Credit: ESA/Rosetta/NAVCAM

Here are a few new photos for your supermoon-drenched eyes today showing comet 67P/C-G in stereo as well as in fresh views from different angles made on August 8th and 9th.

The comet from 50 miles (81 km) on August 8, 2014. Assuming a length of about 2.5 miles for the comet nucleus, I estimated the largest boulder in the boulder field (center-left) at roughly 115 feet (~35-m) across. That’s about 3 school buses parked end to end. Credit: ESA/Rosetta/NAVCAM
What I call the Star Trek Enterprise angle on comet 67P/C-G from August 9, 2014 from 61 miles (99 km). Credit: ESA/Rosetta/NAVCAM

19 Responses

  1. Brian

    Hi Bob, I found that to view the stereo image one has to use the “parallel viewing method,” ie. the eyes diverge until the left eye is centred on the left image and the right is centred on the right image and then focused. If the two images were reversed, then one could use the cross-eye method, where the eyes converge and the left eye is centred on the right image and vice versa.

    1. astrobob

      Interesting. I tried what you suggested but can’t get it to work. I have better results by slightly crossing my eyes to create the third, 3D image.

      1. Brian

        The parallel-viewing method I wrote about is more difficult to do and involves relaxing the eyes so the lines-of-sight of the two eyes becomes parallel. (Kind of like what happens when a person daydreams.) But then one must force their eyes to focus on the image.

        If you can swap the left and right images in a photo editing program, then the cross-eye method will work fine. There is an outcrop (?) on the lower-right nodule (?) that is directed toward the observer that really stands out!

        P.S. Hope you enjoyed the perigee-syzygy yesterday!

          1. Giorgio Rizzarelli

            Bob, there’s possibly some misunderstanding in the messages above. Brian is right… I have some stereograms books which I had showed to various friends and I noticed that most people use the cross-eye system, that is, the right image seen by left eye is made to overlap with the left image seen by right eye (one sees 3 images: left image of left eye, overlap, and right image of right eye, but only focuses attention on the middle overlap). After crossing eyes one has to relax a few seconds and will see the object popping out in front of the screen. To make this work for this comet image the two photos should be swapped. I did this here and it works (and very good for this image by the way).

            If a couple of images is designed to be watched, say, with the cross eye system, and one uses the parallel eye system, he sees it reversed forward-back or inside-out and, if I remember right, behind the screen plane instead of popping out in front. This z-coordinate reversal often works with artistic stereograms, but not with a real 3D object as in this case, which if seen inside-out, is unrealistic so the brain doesn’t trigger it and sees nothing.

            I suggest you pay attention to the difference of the methods. Reading your messages exchange I suspect that what you call cross eye system is really the parallel eyes system.
            I noticed that most persons, if use no glasses or myop glasses, use the cross eyes method, while a minority of persons, generally those who use glassed for reading, tend to use the parallel eyes method. It’s difficult to make people who use one system to try use the other one. Probably the better thing when posting a stereogram of a real object would be to post both versions, but the most used (as published in stereogram books and usually on web) is the one for the cross eye system. Hope this helps 🙂

          2. astrobob

            Hi Giorgio,
            OK, I tried your reversed image panel out and it really does work better! Both the original from ESA and your swap give a 3D impression when ‘eye crossing’ but the swap is far better once the eyes are very relaxed. The crater walls show up in striking relief. I’m going to substitute the reversed image now in the blog. Thanks!

          3. Giorgio Rizzarelli

            You’re welcome Bob. The most important thing is that we don’t all become like Marty Feldman in Frankenstein Jr 😀

  2. Norman Sanker

    That is some major, dizzying 3-D! How do you do on Magic Eye pictures? Love the NYC scale shot. Easy to see that, if an object this size hit the Big Apple, there would be nothing left.

  3. Bruce Elliott

    Thanks for putting together the two halves of the stereo view! I was searching for such images, and so far I’ve only come across yours. Actually – the ESA site does have a red/green stereo image, but I don’t happen to have any glasses with me, so it’s no good to me.

    About the divergent vs. convergent stereo viewing (or cross-eyed vs. parallel, as they are described above) – I’ve been a big fan of stereograms for years, having first generated them for my own amusement back in the late ’80s. I’ve learned to do both the convergent (cross-eyed) and divergent (parallel) techniques, and for me the convergent method is far easier, possibly because that’s the direction my eyes go when they relax – I imagine that’s a physiological thing that varies from one person to the next. For that reason, I do better with the original version of your image, which is what came up in a Google search.

    One advantage of the convergent version is that it works with any size image, limited only by your ability to cross your eyes. With the divergent images, it’s very difficult to get your eyes to aim wide enough if the images are too far apart. In the case of these images, I had to set the zoom factor in my browser to 50% before I could form the image. I guess for people who are naturally wall-eyed, this won’t be a problem!

    Thanks again.

    1. astrobob

      Hi Bruce,
      Thanks for an excellent explanation of the two techniques. I found that the reversed stereo view (not the one first issued by ESA) works much better for me, but I’m sure I’m crossing my eyes when I look at it rather than using the divergent method. ???

      1. Bruce Elliott


        I misread one of your earlier replies and thought that you had swapped the two sides of the image – or maybe you did, and I never saw the original (divergent?) version. The version I see up above is definitely a convergent or cross-eyed image.

        In any case, it’s not too hard to figure out which method is appropriate for a given pair of images, if you can tell the difference between them (it’s not always obvious). If you examine the two images above, you can see that the one on the left is from a viewpoint slightly to the right of the one on the right. This is clearest with the dark hollow at the lower right of the comet. That means that you want your right eye to aim at the left image and your left eye to aim at the right image – i.e. cross your eyes.

        If the images were reversed, you’d want your left eye aimed at the left image and right eye aimed at the right image, which means that they’re actually focused on a point some distance behind the screen (or paper). I usually approach these images by imagining that the screen is a window pane and I’m trying to look at something several inches on beyond the glass.

        Hope that helps!

          1. Bruce Elliott

            The verdict is:

            I could stare at that for hours, except that I keep hearing this voice in my head saying, “If you don’t stop that, your eyes will get stuck that way forever!”

            Yes – cross-eyed convergent stereogram. And absolutely amazing detail on the comet! The pits and pocket are just so much deeper than I’d imagined. It looks like a snapshot of a mud puddle in the rain.

          2. astrobob

            Aha! I figured it was cross-eyed convergent, since I’ve been crossing my eyes since I was a kid. My reaction was a the same as yours – the image is so sharp and real, better in a way than a 3D anaglyph.

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