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Article: 15801 of comp.sys.hp48 From: charliep@hpcvra.cv.hp.com (Charles Patton) Date: Wed, 15 Dec 1993 17:35:59 GMT Subject: 3D Graphics (SIRDS / RDA) Message-ID: <-218869982@hpcvra.cv.hp.com> Organization: Hewlett-Packard Co., Corvallis, OR, USA Path: kth.se!sunic!pipex!howland.reston.ans.net!usc!sdd.hp.com!hplabs!hp-cv!hp-pcd!hpcvra!charliep Newsgroups: comp.sys.hp48 Lines: 870 Hi all, I've included, below, an ascii encoded HP48 directory with the random-dot autostereogram stuff in it for your visualization pleasure. The directory contains five things. EXAMP1 & EXAMP2 are standard-sized grobs with simple stereograms on which to practice your viewing. RDAFUN is the main program. It takes a user-defined function of two variables and generates the stereogram on the '48 screen. It takes a while but I have found that you can begin seeing the 3-D effect after it's about 1/3 done. The user-defined function should take screen coordinates ( [1,131]X[1,64] ) and return an INTEGER (!!!) between 0 and 8. This upper limit was experimentally determined as the useful dynamic range - but try messing around yourself. ONEPIX is the routine to "color" a single pixel based on the past history and current function value. RNDLST is a utility to generate a random sequence of 0's and 1's. Beyond the end of the directory, I've included an FAQ regarding RDAs from a usenet notes group. ******************************************************* ** Charles M. Patton ** ** ** ** charliep@cv.hp.com ** ** the usual disclaimers apply ** ******************************************************* @--------------------begin RDA.DIR------------------------------------------------------------@ %%HP: T(3)A(D)F(.); DIR EXAMP2 GROB 131 64 0F1007300CD200E61007B00C710CB0071040B3446F019B788CD344EE01DD11DE4850AD09AD12A6F015B788AD34A678C674AD000317072C1C11E0E80707481C103C181700044D08863044B102AD001D204A504D20202D192A35A8D925CE49267A88D519DA4650E8D4613399899CC89166CC891B1B1D8620D4AB59CE6946739467B42BB294719A3440941519645843A4843A44A15096A0925440302D30A47105A7105A7182D70AA706D140088A203A6181B6181B61C85303B60B5140847029D109CE009CE0096700AD10AD0820850A1B08E8508E8508E81047608E604B10802A0988484C8484C848464229942948407543E21D0790D0790 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 41F26C50855E89AC3665E13B2F895936E2766999204903411605C03826814134054805044100863986622A9111DC8886622AD40A528A403B0B2B169C60B463852B169C3C8C162340 EXAMP1 GROB 131 64 0A8490A8490A8490A8490A8490A8490A002C6C12C6C12C6C12C6C12C6C12C6C12C60855D2855D2855D2855D2855D2855D28550A8C55A8C55A8C55A8C55A8C55A8C55A84078260782607826078260782607826078201CD221CD221CD221CD221CD221CD221C50C07B4C07B4C07B4C07B4C07B4C07B4C070C8384C8384C8384C8384C8384C8384C8306881068810688106881068810688106800D0E20D0E20D0E20D0E20D0E20D0E20D0606D5106D5106D5106D5106D5106D5106D505D10C5D10C5D10C5D10C5D10C5D10C5D10270AF270AF270AF270AF270AF270AF2700064FC064FC064FC064FC064FC064FC0640596D4596D4596D459 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 20AC620A4010A7810A7810A1608A1608A1608A160820977949779497725ED625ED625ED625ED60710B0710B07102C5802C5802C5802C58000185901859018524085240852408524000D8299D8299D826632366323663236632302946529465294494244942449424494240B4D98B4D98B4D3E29D3E29D3E29D3E2950340E4340E43402D0502D0502D0502D0500488FC488FC488F3188F3188F3188F3180080A0080A0080A0080A0080A0080A008020672B8672B8672B8672B8672B8672B86720E7797E7797E7797E7797E7797E7797E7701416314163141631416314163141631410B3B94B3B94B3B94B3B94B3B94B3B94B3302385923859238592385 238592300E5546E5546E5546E5546E5546E5546E55006E8E06E8E06E8E06E8E06E8E06E8E06600A8490A8490A8490A8490A8490A8490A002C6C12C6C12C6C12C6C12C6C12C6C12C60855D2855D2855D2855D2855D2855D28550A8C55A8C55A8C55A8C55A8C55A8C55A84078260782607826078260782607826078201CD221CD221CD221CD221CD221CD221C50C07B4C07B4C07B4C07B4C07B4C07B4C070C8384C8384C8384C8384C8384C8384C8306881068810688106881068810688106800D0E20D0E20D0E20D0E20D0E20D0E20D0606D5106D5106D5106D5106D5106D5106D505D10C5D10C5D10C5D10C5D10C5D10C5D10270AF270AF270AF270AF 70AF2700064FC064FC064FC064FC064FC064FC0640596D4596D4596D4596D4596D4596D4596006134061340613406134061340613406100030100301003010030100301003010030 FUNRDA \<< \-> FFF \<< PICT PURGE { # 0d # 0d } PVIEW 1 64 FOR YY 20 RNDLST 0 # 0d YY 1 - R\->B 1 YY 1 FFF 0 0 DO ONEPIX UNTIL 6 PICK 132 == END 11 DROPN NEXT \>> \>> ONEPIX \<< \-> LST LSTLEN IDX PX PY X Y DX F OLD NEW \<< CASE OLD NEW == THEN IF 'LST (IDX+1)' EVAL THEN PX PY 2 \->LIST PIXON END LST LSTLEN IDX 1 + LSTLEN MOD PX 1 + PY X DX + Y DUP2 F EVAL DX F NEW 4 ROLL END NEW OLD > THEN LST OBJ\-> IDX - ROLL DROP LSTLEN 1 - DUP 'LSTLEN' STO IDX OVER MOD 'IDX' STO \->LIST 'LST' STO LST LSTLEN IDX PX PY X Y DX F OLD 1 + NEW END LST OBJ\-> IDX - 1 + RAND .6 > SWAP ROLLD LSTLEN 1 + DUP 'LSTLEN' STO \->LIST LSTLEN IDX PX PY X Y DX F OLD 1 - NEW END \>> \>> RNDLST \<< \-> L \<< 1 L START RAND .6 > NEXT L \->LIST L \>> \>> END @--------------------end RDA.DIR------------------------------------------------------------@ Here's the FAQ from alt.3d, complete with credits/advertisements at the bottom and code examples in the middle: -- Ken Corey exukenc@exu.ericsson.com 214/907-5841 Speaking for everyone... God may be subtle, but He isn't plain mean. -- Albert Einstein The following is a smattering of info I've collected about SIRDS. It is not too well organized, nor complete, but it answers a lot of FAQs out there. Please submit any updates/changes to me at thale@novell.com. The following sections are covered herein: SIRDS terminology SIRDS FTP Sites Commercial SIRDS Software HOW STEREOGRAMS WORK <-- By popular demand! Stereogram Algorithm <-- Also new (and rough) SIRDS Publications Sample TEXT Stereograms C Code to Generate SIRTS Hope for the Hopeless Commercial SIRDS Posters ----------------------------------------------------------------------- ----- SIRDS TERMINOLOGY ----------------------------------------------- ----------------------------------------------------------------------- SIRDS Single Image Random Dot Stereogram SIRD Single Image Random Dot (not much to view in a dot; used by newbies) SIRTS Single Image Random TEXT Stereogram, also called ascii stereograms Stereogram general, simplified term for SIRDS and SIRTS and even stereo-pairs (occasionally) Autostereogram, RDS, Auto RDS equivalent to a SIRDS RLS Random Line stereograms, instructional in learning stereogram concepts (see Slinker and Burton publication) Wall-eyed viewing Viewing stereograms by focusing past the actual image Cross-eyed viewing Viewing stereograms by focusing in front of the image Focus to infinity Forcing your eyes' lines of sight into parallel, NOT necessary for wall-eyeing SIRDS! ----------------------------------------------------------------------- ----- SIRDS FTP SITES ------------------------------------------------- ----------------------------------------------------------------------- Submissions from E.Thompson@newcastle.ac.uk, kbaum@novell.com, s ftp.uwp.edu /pub/incoming/graphics/rdsdraw.zip EXCELLENT SIRDS painting/generating program. CHECK IT OUT! wuarchive.wustl.edu (128.252.135.4) /mirrors/msdos/graphics/mindim20.zip Several SIRDS (~32) in an RLE format with versatile viewer. GET IT! /pub/MSDOS_UPLOADS/demos/sirdsani.zip Lets you load a 3d object, position it, then generates an animated rotation within stereograms. /pub/xpgs/xpgs.?.? Xwindows stereogram utilities; generator, viewer, mindim rle viewer... /pub/MSDOS_UPLOADS/graphics/dynamic.exe Animated SIRDS (page flipping) /graphics/graphics/mirrors/sugrfx.acs.syr.edu/3d/randot/3drandot.zoo Converts color GIF to SIRDS on screen /mirrors/msdos/graphics/perspect.zip Simple SIRDS paint/view program sunsite.unc.edu /pub/academic/computer-science/virtual-reality/3d/ alt.3d.Z Older archive of the alt.3d newgroups mindimage Stereogram Viewing package, rle images randot Various programs to make random dot stereograms red_blue Graphic files for viewing with Red/Blue glasses stereograms Graphic and Text files of steroegrams ftp.cs.waikato.ac.nz /pub/papers/???.tar.Z Research paper describing sirds, with several improvements (archive??) shimmer.exe Flips through several SIRDS of the same image to create a shimmering effect (related to above research paper) ----------------------------------------------------------------------- ----- COMMERCIAL SIRDS SOFTWARE --------------------------------------- ----------------------------------------------------------------------- STW_DEMO.EXE: the full package will allow RDS creation Approx 40$ N.E.Thing Enterprises P.O. Box 1827 Cambridge, MA 02139 I know there are more! SEND MORE INFO! ----------------------------------------------------------------------- ----- How Stereograms Work -------------------------------------------- ----------------------------------------------------------------------- Let's start with a simple repeating pattern. First we'll examine viewing stereograms wall-eyed (focusing beyond the picture). Adam Adam Adam <-- PERCEIVED IMAGE (3D) \ \ \ \ \ Adam Adam Adam Adam <-- ACTUAL PICTURE (Flat, 2D) \ \ \ \ <-- LINES OF SIGHT FROM EACH EYE \ \ (*) (*) <-- EYES As shown in the above graphic, the lines of sight go through different (but identical) words. The eyes must be directed to just the right level behind the picture to get the two "Adams" to line up. When they do line up, a single "Adam" appears at the level shown behind the picture. This is why it is easiest for some people to look at stereograms behind glass. You simply look at your reflection, which appears to be behind the glass at about the same level as the 3d stereogram image. More on this later. So, why is the second "Adam" in the above image "deeper" than the other two? Since the next two "Adams" that line up are FARTHER apart than the first two, your eyes must diverge a little more to get them to line up. As the eyes diverge, their lines of sight meet a little further away. This causes the next "Adam" to appear deeper in the image. Adam Adam | Adam <-- PERCEIVED IMAGE (3D) / \ / \ / \ Adam Adam Adam Adam <-- ACTUAL PICTURE (Flat, 2D) / \ / \ <-- LINES OF SIGHT FROM EACH EYE / \ (*) (*) <-- EYES The above graphic was crammed into 10 lines of text. If we moved the eyes back (to a more realistic distance), the whole 3d image would appear deeper, and not so spread out. Cross-eyed viewing follows the same principles, but brings the focal point up front of the picture and inverts the image. I'll use the same eyes and picture, but move the eyes back for room to illustrate. Adam Adam Adam Adam <-- ACTUAL PICTURE (Flat, 2D) \ | \| Adam <-- PERCEIVED IMAGE (3D) | \ | \ | \ <-- LINES OF SIGHT FROM EACH EYE | \ (*) (*) <-- EYES Now for the inverse part. Since the next two "Adams" are farther apart, you must cross your eyes MORE (converge instead of diverge your eyes) to get the "Adams" to overlap. This causes the next "Adam" in the image to appear closer than the first one. Adam Adam Adam Adam <-- ACTUAL PICTURE (Flat, 2D) \ / \ / Adam\ / Adam <-- PERCEIVED IMAGE (3D) Adam / \ / \ <-- LINES OF SIGHT FROM EACH EYE / \ (*) (*) <-- EYES Whew. Ascii graphics are a bit too tight to be very technical. By the way, each letter (or pixel) in the 3D image comes from two letters in the picture. Stereograms have blurry edges (right and left edges) because the line of sight from the one eye passes through the picture, but the line of sight from the other eye is off the picture. Examine the wall-eyed example below. Adam Adam Adam <-- PERCEIVED IMAGE (3D) \ \ \ \ \ \ Adam Adam Adam Adam <-- ACTUAL PICTURE (Flat, 2D) \ \ \ \ <-- LINES OF SIGHT \ \ (*) (*) <-- EYES Here, the line of sight for the right eye goes through first "Adam" in the picture, and the line of sight for the left eye is off the picture. (Everything to the left of the first "Adam" in the IMAGE is blurry.) HOW TO GENERATE STEREOGRAMS Random stereograms work the same way; they simple repeat random text or pixels, instead of words like the "Adam" used above. Below, the pattern, "ASDFGHJK", is repeated four times in each line. (I duplicated it for easier viewing.) ASDFGHJKASDFGHJKASDFGHJKASDFGHJK ASDFGHJKASDFGHJKASDFGHJKASDFGHJK ASDFGHJKASDFGHJKASDFGHJKASDFGHJK As you might guess, the image consists of THREE repetitions of the pattern, set back behind the picture (wall-eyed). To add some varying depth to the image, we can simple add a space in the middle; or better, we'll add a different letter, the letter Q. I've also dropped the K off the end to keep it suitable for framing. :-) ASDFGHJKASDFGHJKASDFGHJKASDFGHJK ASDFGHJKASDFGHJKASQDFGHJKASDFGHJ ASDFGHJKASDFGHJKASDFGHJKASDFGHJK Adding the Q has the same effect as adding the space between "Adams" in the previous example. Here it is again for comparison. Adam Adam Adam Adam Adam Adam Adam Adam Adam Adam Adam Ada Adam Adam Adam Adam Adam Adam These two stereograms demonstrate going down a level (deeper, for wall- eyed viewers) by adding a new letter where you want to go down. The image returns back to the original level because the added letter was not repeated down the line; it was essentially deleted again. Hence, deleting a letter causes the image to come forward one level. Lets look at this by deleting a letter before adding any. ASDFGHJKASDFGHJKASDFGHJKASDFGHJK ASDFGHJKASDFGJKASDFGHJKASDFGHJKA ASDFGHJKASDFGHJKASDFGHJKASDFGHJK I deleted an H from the middle row, and added an A on the end to make it flush again. This causes the image to come up a level where the H was deleted, then go back down where the H returns to the pattern. To fully control the ups and downs of stereogram generation, you simply keep track of what's repeating and add and delete letters when needed. For example, start with the pattern ASDFGHJK. If the input for the 3D stereogram image is 00000000000011111222221111111110000, where the numbers represent the levels of the 3D image, you simply delete a letter from the pattern when you go up a level (0 to 1, or 1 to 2), and add a letter to the pattern when you go down a level (2 to 1, or 1 to 0). If you want to go up multiple levels, e.g., from level 1 to 3, delete 2 letters from your pattern. Adding two letters to the pattern likewise causes a two level drop in the image. Start each line by dumping the whole pattern before you start creating the image. Recall that in the examples above, four "Adams" in the picture creates three "Adams" in the image. By dumping the pattern to start, we are simple providing the first "Adam" to build the 3D image from. Now, we start building the 3D image. ASDFGHJK Since the first 12 levels are at level 0, we do no adding nor deleting; just dump 12 more letters from the pattern in order. ASDFGHJKASDFGHJKASDF ^image starts here We now have our first transition, from level 0 to 1. Which letter do we delete? Delete the next one in the pattern. ASDFGHJK ^the next letter in the pattern Since G is next, we delete it. Our new pattern is ASDFHJK, and H is the next letter to be used in the image. ASDFHJK ^the next letter to use in the image Forget about the G. Consider it gone forever. The input now indicates five letters at level 1. Since we made the transition to level one by deleting the G, we simply copy the next 5 letters from the pattern into the image. The next 5 letters in the pattern are HJKAS. (You've noticed by now that we wrap around when we get to the end of the pattern.) I'll lay the input next to our image to make it easier to see where we're at. 00000000000011111222221111111110000 ASDFGHJKASDFGHJKASDFHJKAS { }{ }{ } initial level 0 level pattern 1 To jump up to level 2 from level 1, we delete the next letter in the pattern, the letter D. The new pattern is shown below. ASFHJK ^the next letter to use We have 5 letters at level 2, so we copy the next 5 letters from the pattern, FHJKA, to the image. 00000000000011111222221111111110000 ASDFGHJKASDFGHJKASDFHJKASFHJKA { }{ }{ }{ } initial level 0 lev level pattern 1 2 We must now move down a level, from 2 to 1, by ADDING a letter to our pattern. Where do we add it? Add it as the next letter to use. Let's add an X (randomly chosen letters work better than previously used letters). Since A was the last letter used, S is the next to be used. ASFHJK ^add X here AXSFHJK ^next letter to use Since there are nine letters at level 1, we must copy nine letters from the pattern to the image (XSFHJKAXS). 00000000000011111222221111111110000 ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXS { }{ }{ }{ }{ } initial level 0 lev level level 1 pattern 1 2 Drop another level, from 1 to 0, by adding another letter to the pattern at the current position. AXSFHJK ^add random letter (M) here AXSMFHJK ^next letter to use Since there are four letters at level 0, we copy four letters from the pattern to the image (MFHJ). 00000000000011111222221111111110000 ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ { }{ }{ }{ }{ }{ } initial level 0 lev level level lev pattern 1 2 1 0 WE'RE DONE. Kinda anti-climatic, huh? Let's duplicate the image line to make it easier to view. ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ ASDFGHJKASDFGHJKASDFHJKASFHJKAXSFHJKAXSMFHJ For each new line in the image, start with a new random pattern, and follow the steps above. So, how are graphics stereograms made? The same way, using colored pixel values for input. 3drandot uses RED as the color deepest in the image, with GREEN in the middle, and BLUE as the highest color. The pseudocode below follows this algorithm. If you have any questions, post them in the newsgroup. Let me know if you are interested in C code that follows this algorithm. The C code here in the FAQ follows a different algorithm, the "lookback" algorithm. Enjoy!! thale@novell.com ----------------------------------------------------------------------- ----- STEREOGRAM ALGORITHM -------------------------------------------- ----------------------------------------------------------------------- The following is an algorithm I developed for SIRDS generation. It is functionally equivalent to the look back algorithms, without looking back. It can be used for graphic stereograms, as well as the text stereograms. It simply stores in PATTERN the values we would look back at. The input file is depth data, or a z-buffer (see example input below). The levels available in a picture are the maximum pattern size divided by two minus one. Maximum pattern size should be equivalent to half the distance between the eyes (for easy viewing), which is about 1 1/4 inches. So, for typical text stereograms on an 80 char display, that's about 10 characters for the maximum pattern size and 4 or 5 levels available. However, since 4 or 5 levels is unreasonable, we push the max pattern size to 16 (still less that the 20 character distance between the eyes). This gives us about 7 or 8 levels. If we do allow more than 7 levels when the max pattern size is 16, the repeating pattern (of size max pattern - current level) grows so small that four of them in a row (e.g., of size 7) would also create two double patterns in a row (of size 14), causing floaties (aliasing). I hope I'm making some sense. I'll try to spend some time rewriting this. In addition, I'll integrate answers to any questions that come as a result of this mess! In addition to the information here, we need to add a good description of how they work (that is not covered here). PL : Previous Level value NL : Next Level value INITIAL LEVEL SETTING PL = 0 OPEN INPUT FILE FOR READING WHILE NOT EOF (Y DIMENSION: FOR EACH LINE) GENERATE NEW PATTERN SET PATTERN PTR TO BEGINNING OF PATTERN OUTPUT FULL PATTERN WHILE NOT EOL (X DIMENSION: FOR EACH POSITION) NL = NEXT INPUT LEVEL VALUE IF NL != PL (IF WE'RE CHANGING LEVELS) IF NL > PL (IF WE'RE MOVING UP) DELETE NEXT NL-PL BITS IN PATTERN FROM PTR FORWARD (IF GOING FROM LEVEL 0 TO 2, DELETE 2 BITS IN PATTERN) ELSE (IF MOVING DOWN, AWAY) INSERT PL-NL RANDOM BITS INTO PATTERN AT PTR POSITION (IF GOING FROM LEVEL 3 TO 2, INSERT 1 BIT INTO PATTERN) PL = NL (UPDATE PL) OUTPUT NEXT VALUE IN PATTERN ELSE OUTPUT NEXT VALUE IN PATTERN ADVANCE PATTERN PTR (CIRCULAR PATTERN) ADVANCE INPUT PTR (Redundancy exists to simplify readability.) Assuming spaces translate to level 0, input like this (thanks, Dave Thomas): 22222222222222222 11111111111111111111111 2222222222222222222 11111111111111111111111 22222222222222222222 11111111111111111111111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222222222222222222 11111 2222222222222222222 11111 22222222222222222 11111 Yields output like this: Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D mwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`, 7Z,o:.sw5[rHt&{:7Z,osw5[rHt&{:7Z,osw505[rHt&{:7Zosw505[rHt&{:7Zosw505[rR g"EzQy{lW_3C&B[8g"Ez{lW_3C&B[8g"Ez{lW_3S3C&B[8g"z{lW_3S3C&B[8g"z{lW_3S3y yiQ?fiVF!G{TAtrJyiQ?VF!G{TAtrJyiQ?VF!G{T]TAtrJyi?VF!G{T]TAtrJyi?VF!G{T]s 1`I|r?FLoB#<sf!Q1`I|FLoB#T#<sf!Q1`ILoB#TaT#<sf!Q1`ILoB#Ta#<sf!#Q1`ILoB#T m$LuSD0hh7\qy5:nm$Lu0hh7\x\qy5:nm$Lhh7\x"x\qy5:nm$Lhh7\x"\qy5:-nm$Lhh7\x [#7hrqKUm`/<bic$[#7hKUm`/7/<bic$[#7Um`/7r7/<bic$[#7Um`/7r/<bick$[#7Um`/7 L,'O)X\L&Xu)ZUw(L,'O\L&Xu|u)ZUw(L,'L&Xu|y|u)ZUw(L,'L&Xu|yu)ZUwy(L,'L&Xu| 3`#YPTdg:,;rmy9`3`#Ydg:,;(;rmy9`3`#g:,;(7(;rmy9`3`#g:,;(7;rmy94`3`#g:,;( 1w^N7d;f964U,yml1w^N;f964&4U,yml1w^f964&;&4U,yml1w^f964&;4U,ym{l1w^f964& <>Y8igID(]?"A0+;<>Y8ID(]?"A0+;<>Y8ID(]?"?"A0+;<>Y8ID(]?"?A0+;<O>Y8ID(]?" eRl5hfJx.cD0tscheRl5Jx.cD0tscheRl5Jx.cDeD0tscheRl5Jx.cDeDtscheiRl5Jx.cDe v,r7f6%<)R-AaV^hv,r7%<)R-AaV^hv,r7%<)p)R-AaV^hv,r7%<)p)R-aV^hv>,r7%<)p)R VbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]q `^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v= This uses 16 as the Max pattern size. Notice on the third line of the output (the first line with level changes), the pattern is "7Z ... &{:". When we go from level 0 to level 2, we lose two characters (i.e., ":."). When we go from level 2 back to level 0, we insert two new characters (i.e., "05" after the "osw5"). Any questions? Or better yet, what did I leave out?? I do hope this helps someone!?! ----------------------------------------------------------------------- ----- SIRDS PUBLICATIONS ---------------------------------------------- ----------------------------------------------------------------------- Search library databases with these keywords: Stereogram, Autostereogram, SIRDS (Single ImageRandom Dot Stereogram), RDS. >From E.Thompson@ncl.ac.uk An excellent source of information (sample RDS and source code) is contained in Andrew A.Kinsman - Random Dot Stereograms ISBN 0-9630142-1-8 $13.95 U.S. Published by Kinsman Physics, P.O. Box 22682, Rochester, N.Y. 14692-2682 See the following periodicals: Journal of Imaging Science and Technology, May/June 1992, Vol 36, #3. Slinker & Burton SEND MORE REFERENCES! ----------------------------------------------------------------------- ----- SAMPLE TEXT Stereograms (Not random) ---------------------------- ----------------------------------------------------------------------- From: dthomas@bbx.basis.com (Dave Thomas) O O n n n n n n n n n n n n n n n n f f f f f f f f f f f f f e e e e e e e e e e e e e e e e a a a a a a a a a a a a a a a a a a a a a a a a a a a a a r r r r r r r r r r r r r r r r r r r r r r r r r r r r r g g g g g g g g g g g g g g g g g g g g g g g g g r r r r r r r r r r r r r r r r r r r e e e e e e e e e e e e e e e a a a a a a a a a a a a a t t t t t t t t t t t <<<<>>>><<<<>>>><<<<>>>><<<<>>>><<<<>>>><<<<>>>><<<<>>>><<<<>>>><<<<>>>> d d d d d d d d d d d e e e e e e e e e e e e e p p p p p p p p p p p p p p p t t t t t t t t t t t t t t t t t t t h h h h h h h h h h h h h h h h h h h h h h h h h One more from ... well ... YOU figure it out! _-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~ ! Adam Adam Adam Adam Adam Adam ! "Lawn ! !Spragg Spragg Spragg Spragg Spragg Spragg Spragg! service!" ! ! Adam Adam Adam Adam Adam Adam ! -Stup ! !Spragg Spragg Spragg Spragg Spragg Spragg Spragg! ! ! Adam Adam Adam Adam Adam Adam ! atspragg@ ! !Spragg Spragg Spragg Spragg Spragg Spragg Spragg! ucdavis.edu ! ! Adam Adam Adam Adam Adam Adam ! GO AGS! ! _-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~-_-~ ----------------------------------------------------------------------- ----- C CODE TO GENERATE TEXT STEREOGRAMS ----------------------------- ----------------------------------------------------------------------- Also from Dave Thomas: Now here's a hack of a hack I found on the net. Basically it generates stereograms from ascii diagrams. Here's the program first: #define DEPTH0 16 #define COLS 79 #include <stdio.h> main() { long now; int col; char m[COLS+1],s[COLS+1]; int i,e,c; /* seed random number generator */ time (&now); srand (now); /* print fusion X's */ for (col = 0; COLS - col >= DEPTH0; col += DEPTH0) { for (i = 0; i < DEPTH0-1; ++i) putchar (' '); putchar ('X'); } putchar ('\n'); /* process input image */ while (memset(m,'\0',COLS+1),fgets (m, COLS+1, stdin)) { e = 0; s[COLS] = 0; for(i=0; i<COLS; ) { e = 0; while (i >= DEPTH0 && i < COLS && (c = m[i - DEPTH0]) >= '0' && c <= '9') { e = 1; s[i] = s[i-DEPTH0+c-'0']; ++i; } s[i++] = (e || i < DEPTH0) ? randasc() : s[i-DEPTH0]; } puts (s); } } randasc() { /* large set of random characters */ return ('!'+rand()%92); /* lowercase random letters */ /* return ('a'+rand()%26); */ } Try passing it this file as the standard input: 22222222222222222 11111111111111111111111 2222222222222222222 11111111111111111111111 22222222222222222222 11111111111111111111111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222 22222 11111 22222222222222222222 11111 2222222222222222222 11111 22222222222222222 11111 You'll get output like this: X X X X "i`<$$Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D(v"i`<$$Co6&`R(D dZ<$wamwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`,QFdZ<$wamwBy&>`, rHt&{:7Z,o:.sw5[rHt&{:7Z,osw5[rHt&{:7Z,osw505[rHt&{:7Zosw505[rHt&{:7Zosw505[rR 3C&B[8g"EzQy{lW_3C&B[8g"Ez{lW_3C&B[8g"Ez{lW_3S3C&B[8g"z{lW_3S3C&B[8g"z{lW_3S3y {TAtrJyiQ?fiVF!G{TAtrJyiQ?VF!G{TAtrJyiQ?VF!G{T]TAtrJyi?VF!G{T]TAtrJyi?VF!G{T]s #<sf!Q1`I|r?FLoB#<sf!Q1`I|FLoB#T#<sf!Q1`ILoB#TaT#<sf!Q1`ILoB#Ta#<sf!#Q1`ILoB#T \qy5:nm$LuSD0hh7\qy5:nm$Lu0hh7\x\qy5:nm$Lhh7\x"x\qy5:nm$Lhh7\x"\qy5:-nm$Lhh7\x /<bic$[#7hrqKUm`/<bic$[#7hKUm`/7/<bic$[#7Um`/7r7/<bic$[#7Um`/7r/<bick$[#7Um`/7 u)ZUw(L,'O)X\L&Xu)ZUw(L,'O\L&Xu|u)ZUw(L,'L&Xu|y|u)ZUw(L,'L&Xu|yu)ZUwy(L,'L&Xu| ;rmy9`3`#YPTdg:,;rmy9`3`#Ydg:,;(;rmy9`3`#g:,;(7(;rmy9`3`#g:,;(7;rmy94`3`#g:,;( 4U,yml1w^N7d;f964U,yml1w^N;f964&4U,yml1w^f964&;&4U,yml1w^f964&;4U,ym{l1w^f964& ?"A0+;<>Y8igID(]?"A0+;<>Y8ID(]?"A0+;<>Y8ID(]?"?"A0+;<>Y8ID(]?"?A0+;<O>Y8ID(]?" D0tscheRl5hfJx.cD0tscheRl5Jx.cD0tscheRl5Jx.cDeD0tscheRl5Jx.cDeDtscheiRl5Jx.cDe -AaV^hv,r7f6%<)R-AaV^hv,r7%<)R-AaV^hv,r7%<)p)R-AaV^hv,r7%<)p)R-aV^hv>,r7%<)p)R IRW)ytVbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]qi(IRW)ytVbWqd^]q BX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v=[gBX(Aqq`^Y-z8v= ----------------------------------------------------------------------- ----- HOPE FOR THE HOPELESS :-) --------------------------------------- ----------------------------------------------------------------------- From: wchaga@vela.acs.oakland.edu (William C. Haga) Being one who has used wide-eyed vision on chain link fences ever since I was a kid, I was able to see the images in SIRDS right away. But I've had difficulty explaining the technique to friends. Today I had the latest Games magazine with me at my parents house. Games is running another contest using SIRDS, so there are three in the latest issue. This time I thought of the reflection idea. So I opened mom's china cabinet, put the magazine against the glass in the door, and told mom to keep looking at her own reflection in the glass until the image appeared. It took less than thirty seconds. When she saw the 3d train engines, I was subjected to a squeal of delight that I hadn't heard from her for a long time. "EEK! IT'S COMING OUT AT ME! IS THIS EVER NEAT!". Dad tried for about a minute but gave up. About an hour later, mom and I heard a shout. We went to the dining area, and there was dad with the magazine against the glass in the door. "Isn't that just the most amazing thing!", said he. Later they were making jokes about teaching old dogs new tricks. ----------------------------------------------------------------------- ----- COMMERCIAL SIRDS Posters ---------------------------------------- ----------------------------------------------------------------------- From: thale@novell.com (Todd D. Hale) For those who do not have a local SIRDS distributor (i.e., the poster cart at the mall), here is one company you can order them from. The following posters are all certifiably cool with lots of great details, and come in nice colors. They are (I believe) designed by NVision, or something like that, and distributed here by Axis Corp. Posters:$25 Dinosaurs $25 Discovery (Space shuttle and planet) $25 Lady Liberty (U.S. Statue of Liberty) $25 B-2 Stealth Bomber $25 F-117 Bomber $25 Nature's Majesty (Eagle with fish in talons, pine trees in bkgrd) $30 Calypso Reef (Ocean Scene--new design, more detail) Many more now, including small, $15 posters. Address:Axis Corp. 1732 S. 790 W. Salt Lake City, UT 84104 USA Phone: (801)977-8816 You must include $5 for shipping and a poster tube. (The guy quoted me that price for shipping to Australia.) Or, you can pay $17 for a tube in a box. Although they haven't had any problems shipping in the poster tubes, they only guarantee safe delivery in a well-packed box. Since I'm writing from the U.S., all currency mentioned here is in U.S. dollars. And, by no means am I associated with these guys at all, except I spend a lot of time enjoying their posters! (i.e., this is not an ad, but a response to a request for SIRDS access.) ANOTHER SUPPLIER: Infix Technologies PO Box 381 Orem, UT 84057-0381 (801) 221-9233 Shipping now: 18x24 Earth (mercator projection of the Earth's altitudes) 18x24 Salt Lake LDS Temple Centennial Later this week?: 18x24 Beethoven (others are coming soon, too.) Retail price for the 18x24 inch prints is $20 plus $3 s/h. Utah residents add 6.25% sales tax. Wholesale and distributor discounts are available. Quotes for custom work are also available. Cost and minimum order varies, based on content. John M. Olsen jolsen@nyx.cs.du.edu Todd D. Hale thale@novell.com halet@ernie.cs.byu.edu --------------------------------- _ /X\ ------------------ Unofficially speaking, of course. :^/_/__// \\_ relax! ----------------------------------------- \__ --------------------------