Post-Conjunction at Home Plate North, Getting ready to leave |
Post-Conjunction at Home Plate North, Getting ready to leave |
Dec 15 2008, 07:12 PM
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Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
Conjunction is over, so it is probably a good time to start a new thread.
I just saw this update from Scott via Twitter QUOTE ('marsroverdriver') Out of solar conjunction & planning to drive Spirit again. Woo-hoo! Come on, little hill-climber, you can do it! -------------------- |
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Jan 15 2009, 06:27 PM
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
Well, I don't know if there is a proper name for that style of anaglyph, but "constant-depth" seems to fit. Have a look at the recent official Bonestell stereo pan on this page. (I was looking at the "medium image" version.)
Look for example at the far right side of that stereo pan. The foreground surface and rocks appear set slightly back from the surface of your monitor. An easy way to see this is to place the mouse cursor at the patch of surface in question and then you can see that the surface in the foreground is slightly behind the mouse cursor. Now, still on the far right side of that pan, do the same for Husband Hill. You'll see that Husband Hill appears at the same depth as the monitor surface. (You can also see this by noticing that the two colour channels line up for Husband Hill.) But the background/horizon should appear much farther back than the foreground! So in this case the depth is going the wrong way: in the official Bonestell stereo pan the foreground appears farther than the horizon, at least on the right side of the pan. Compare with James's stunning anaglyph pan. You can see similar effects all over the official pan, and on other official pans. I believe what has been done to the official pans is that a shear has been introduced to one (or both) of the stereo channels to "flatten" the stereo effect over the range of distances from foreground to horizon. Think of what a bare, unprocessed anaglyph would look like that extends from nearby ground to the horizon. If you line the two channels up at the horizon, they get progressively out of alignment towards the foreground. So you could imagine applying a shear to one frame, that leaves the horizon unchanged at the top, but progressively shifts the pixels to the right or left as you move down the frame to the foreground, in just such a way as to keep the two channels always (nearly) aligned. Then viewing the resulting anaglyph would be like looking perpendicularly at a wall. Of course small hills, rocks, ridges, dunes, etc would still stand out in 3D, since the shear you applied is smooth and gradual. It looks like this is being done to official stereo pans. I would guess the reason is to make it easier to view a stereo pan that extends over a great range of depth, foreground to horizon. Basically you compress the "dynamic range" of depth greatly. Some people have a very hard time viewing anaglyphs and the more exteme the depth range the harder, I think. And, like I said, you can still see smaller features like ridges, rocks, etc in more or less proper 3D. But I don't like the result! Sorry about the longwinded response - you can see why I didn't give any details in my previous post! |
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