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Scott Watson
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Reged: 05/26/06

Re: Lunar craters inverting illusion new [Re: photonovore]
      #3651676 - 02/27/10 08:48 PM

It isn't so much an optical illusion as an optical ambiguity. I studied this phenomenon in graduate school and found that if you take an image (like a crater) that can be interpreted as either concave or convex and you tell the subject that it is one of the other, they will usually interpret that way. If you don't tell them anything, they will usually interpret it as a crater. It seems we default to the most common interpretation from our previous experience.

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Carol L

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Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W
Re: Lunar craters inverting illusion new [Re: Scott Watson]
      #3659341 - 03/03/10 10:47 PM

Here's another graphic which illustrates the "reversible perspective" illusion (great to see you again, Mardi!).
blister -vs- crater

They look like blisters until you turn the image upside down.


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photonovore
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Reged: 12/24/04

Loc: tacoma wa
Re: Lunar craters inverting illusion new [Re: Carol L]
      #3660055 - 03/04/10 10:36 AM

Hi Carol! Just like old times, mm? That is an excellent illustration of the effect. I made an animated gif of the opposite images just for fun... Crater-dome Illusion

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calibos
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Reged: 11/18/07

Loc: Ireland
Re: Lunar craters inverting illusion new [Re: photonovore]
      #3679932 - 03/14/10 08:22 AM

If only I could switch views as easy on the moon in real life. I was able to switch from blisters to craters very easily without even looking at the image upside down. Pity its not that easy on the moon.

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revans
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Re: Lunar craters inverting illusion new [Re: calibos]
      #3694540 - 03/20/10 09:28 PM

When I have a hard time deciding if I'm looking at a crater or a dome in a photo or on the moon, I usually check the bright areas of the crater rims to see if they are on the right or left. The opposite side will usually be in shadow. The lighting pattern on raised structures like domes is usually the opposite of what it is on adjacent craters. So if craters are bright on the left and dark on the right, then domes or raised structures will be dark on the left and bright on the right. I don't know if this is always true, but I find it to be a help...

Rick


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BillP
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Reged: 11/26/06

Loc: Vienna, VA
Re: Lunar craters inverting illusion new [Re: russell23]
      #3695917 - 03/21/10 03:34 PM

I remember the first time it happened to me...boy was I shocked. I find it is easy to flip also, so many times if I blink my eye and concentrate I can make it reverese at will. Like everything else, it's probably just a perspective interpretation thing with the brain. I've never seen it happen though with the binoviewer, always just in mono mode. Has anyone had this happen to them with the binoviewer??

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photonovore
Moonatic
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Reged: 12/24/04

Loc: tacoma wa
Re: Lunar craters inverting illusion new [Re: BillP]
      #3699919 - 03/23/10 12:20 PM

yes, in a binoviewer. The illusion doesn't seem to be particularly affected by bino/monocular vision. test it on the gif I posted earlier...

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russell23
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Reged: 05/31/09

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Re: Lunar craters inverting illusion new [Re: photonovore]
      #3730416 - 04/07/10 01:32 PM

Ok, I just had another example of this effect. I was reading an article in a magazine that was discussing whether or not there are cougars in upstate NY (reports of sightings are common even though there is no physical evidence confirming them).

So I flipped the page and there was this picture which showed tracks in the snow with a tail print trailing between the footprints. When I first looked at it I saw the same illusion as with the lunar craters. The footprints looked like domes and the tracks left by the tail looked like a raised ridge. I couldn't get the effect to go away until I flipped the magazine upside down.

We were sitting in the dentists office when I saw it and I didn't say anything to my wife until on the way home. I was describing effect as seen on the Moon and then mentioned the picture and she said "Oh - you saw it too! I thought it was just me seeing things wrong."

Dave


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star dropModerator
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Re: Lunar craters inverting illusion new [Re: russell23]
      #3731173 - 04/07/10 07:05 PM

Strange things happen in the dentists office. Oh yes.

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meteorite

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Reged: 01/28/06

Re: Lunar craters inverting illusion new [Re: star drop]
      #4446356 - 03/13/11 10:07 AM

I am happy to have found this thread because this very things happend to me last night. I had just started observing. I was not fatiged. Moon half-full. I was uisng 193x on the moon (somehing I don't normally do) and bam - the craters were elevated. The illusion just kept flip-flopping. It was the strangest thing. At first I thought someting was wrong with my equipment but no, everythig else I observed ws normal.

As soon as darkness falls this evening, I'm going back out! I want to see if this happens again!!!

-Walt


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UmaDog
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Loc: Basel, Switzerland
Re: Lunar craters inverting illusion new [Re: meteorite]
      #4446522 - 03/13/11 11:36 AM

The concave/convex illusion is well known. Here is a classic example:
www.youtube.com/watch?v=0QgoX78q-0Y

Basically, some objects are ambiguous regarding whether they are concave or convex. In these cases the brain makes a choice as to which it is based on what is most likely. This is the case with the face illusion. Viewed from in front, you always see that as a convex face even if you know that it isn't. It's hard or impossible to see it as concave until it has rotated.

The convexity of an object depends upon which way the shadows fall. In other words, on the arrangement of dark and light regions in an image. The weird thing is that you can even see illusory motion if the pattern of light and dark is arranged correctly. The following are coloured but also work as gray-scale. Check it out:
www.ritsumei.ac.jp/~akitaoka/index-e.html
www.psy.ritsumei.ac.jp/~akitaoka/volcanoislands.jpg


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cpsTN
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Re: Lunar craters inverting illusion new [Re: russell23]
      #4451971 - 03/15/11 05:26 PM

This is one of two threads going on now about the same topic. I thought I would repost what I said in the other thread:

I would say that since the Moon is literally only light and shadow with no real perceivable color, it depends upon whether your mind concentrates on the bright parts or the dim parts. Depending upon which part - the light or the dark - your mind sees as the "main" scene will make the other parts look like they are either lower or higher than it is. Have you ever seen the siloettes(sp) of the two faces looking at each other. If you look and the outside colors, you see two faces looking at each other. If you look at the different color separating the two faces, you will see a vase. Sometimes when I am looking at a world map that is only dual color (water and land), I see the water as the main optical piece and can no longer see the outline of the continents. Its all about mental priority!


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Rossmon
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Reged: 07/09/10

Loc: Marin County, CA
Re: Lunar craters inverting illusion [Re: photonovore]
      #6243906 - 12/10/13 12:04 AM

I looked up this thread with a gsearch because it
has been getting more common for me when looking at the
moon. I am not fatigued or anything else just
looking with near perfect seeing and it happens. if I look away or
try looking differently it may go away. using my denk2 bino, 2 Denk 21's
and my 155edf. saw the explanation above. Neat!


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