Stereogram pairs

[Welles]

Speaking of stereograms and other forms of 3D visual creations... I just received a notification of an update to an inexpensive shareware, 3D Maker which creates analyglyphs, stereograms and 3DMF (both Mac and Windows) from common images and pictures. It isn't the most sophisticated but is really cheap and fun. Plus on the web site I'll reference, at the top of the page are three links to pages which are very good introductory descriptions of the technical aspects and/or history of these 3D forms.

http://www.tabberer.com/sandyknoll/m...r/3dmaker.html

[gwpriester]

For what it is worth, next month's Xara Xone Featured Artist Gallery will feature 20 new stereogram images plus a new stereogram tutorial.

I have been using two stereogram creation products, Stereogram Explorer and 3D Miracle. Both produce excellent results.

In the last year, I created and sold over 200 stereogram images. Stereograms are alive and well.

Gary

[simsmj]

Apologies for the delay in posting the .xar file, I had to redo it with a reduced size/resolution bitmap to get the file size down, and decided to re-organise the layers and shapes as part of a more consistent approach. File is only 132K, now.

The top layer contains outlines of the shapes I broke the bitmap into, and the approximate horizontal pixel offsets I used with them.

Since I was working on the left hand image, and viewed the two converged, ie cross-eyed, offsetting, say, a hilltop rightwards a pixel at a time makes it apparently recede into the distance, while leftwards makes it approach the viewer.
Also, as small gaps may then appear between shapes, another copy of the unmodified image is placed below the modified one to act as a background.

Mike

[gwpriester]

Mike

Would it help if you had three images instead of the two? Might make it easier to merge the images.

Gary

[simsmj]

Gary

I'm not sure I follow you, well, actually I am sure, I'm not following you.

Where would you place the 3rd image? Are we talking about a copy of one of the L or R images? It seems to me wherever you placed it you still have to converge an L and an R image into one fused image, and this is easiest to do if the L and R are as closely adjacent as possible.

If the third image is at one side of the current L+R pair, it won't take part in the fusion, and if it was in-between, you would have to move the L+R pairs apart to make room, so the eyes would have to converge further to skip over it, unless that 3rd image was a copy of the L or R, in which case you can lock onto it instead, and so are still overlapping adjacent images anyway.

The real difficulty is the extent that the eyes have to cross over to get the two images to overlap, and the further away the viewer is, or the smaller the images, the less convergence is necessary. Something like Dmitri's mirror stereoscope or other optical intervention is the only other option, I think.

You can do it with a single mirror. In the example diagrammed below, the right hand image must be reversed so that it will be correct when seen in the mirror. I will post an image pair next that can be viewed this way. Look at the left hand image with both eyes as normal, focussing on one spot. Place the edge of the mirror against your nose, and adjust it to reflect the view of the equivalent spot in the right hand image to the right eye so that it comes into line with the spot you were looking at on the left hand image. You won't need to do anything funny with your eyes at all, let the mirror do the work.

Mike

[simsmj]

The right hand image of my original post was flipped, and then the whole pair was flipped because the eyes would see the depth reversed by the new method of viewing.

Mike

[gwpriester]

Here is what I was referring to. I think you need to use the crossed eyes method to view the image. You should see four images not three.

The background photo has been shifted outwards about 4 pixels on the two outside squares. The 3D text has been rotated as your eyes might see it from the same spot, and the three gold spheres should appear to float above all the other elements.

That make any sense?

Gary

[simsmj]

Gary, if I try converging them the depths are back to front. If I go up close to the screen and try a diverging view, then it works as you describe, with correct depth. I can merge L+M, or M+R, and see four images, the two middle ones in stereoscopic 3d. I can converge/merge the outer two images, but this exaggerates the reversed depth, and I cannot diverge/merge the outer two, which should exaggerate the normal depth.

I just had my son look at your post and he sees what you describe easily, he is Diverger, and he tried my mirror suggestion on my post, and got that quite easily, too. But neither of us thought that the third image helped, sorry.

Mike

[gwpriester]

Since this is one of the few topics where people can actually see stereograms...

Gary

[fencepost]

Wonderful tutorial Gary! Thanks for the nice effort. After reading this thread, I purchased the 3D Magic program just to play with. I've been having a blast creating "flat" stereograms (they don't look as good as those produced by the 3D Miracle program, however). I don't use Xara X, because I don't do very advanced type of graphics work, but I may be able to modify your tutorial to work with my graphics program to give my "flat" stereograms some needed depth.
I especially liked the inclusion of floaters and the way you made the background appear to have depth.

Thanks again!

Art