{"id":2337,"date":"2009-12-14T23:23:27","date_gmt":"2009-12-14T15:23:27","guid":{"rendered":"http:\/\/nick.onetwenty.org\/?p=2337"},"modified":"2009-12-14T23:23:27","modified_gmt":"2009-12-14T15:23:27","slug":"stereograms-and-anaglyphs","status":"publish","type":"post","link":"https:\/\/nick.onetwenty.org\/index.php\/2009\/12\/14\/stereograms-and-anaglyphs\/","title":{"rendered":"Stereograms and anaglyphs"},"content":{"rendered":"

I’ve recently been working on various stereographics in preparation for the upcoming Summer exhibition<\/a> (opening next Tuesday at Little Creatures<\/a>). I’ve previously mentioned<\/a> my love for stereographics, but I wanted to write a post with a bit more detail…<\/p>\n

I’m technically inclined, mostly work in digital media, and advocate open source<\/a> software. Accordingly, when trying to generate stereographics, I tried a bunch of open source programs and ended up writing a few small programs (python<\/a> scripts) to solve problems I encountered.<\/p>\n

The two main types of stereographics I’m interested in are anaglyphs<\/a> (red\/blue 3D images) and autostereograms<\/a> (“magic eye” images). I also like crossed stereo pairs, since I find them relatively easy to view as 3D images.<\/p>\n

Autostereograms are generally created from a depth map<\/a> describing a particular viewpoint of a 3D scene, but other stereographics are usually created using a stereo pair of images (representing unique views from two “eyes”).<\/p>\n

I wanted a stereographics creation process that was accessible to 2D artists, and drawing two unique views (and making sure that they match!) seemed like a very difficult task. However, I figured that many 2D artists would be able to draw greyscale depthmaps. So I went about writing a program to generate stereo pairs when provided with a depth map.<\/p>\n

When looking for a depth map to test with, I immediately thought of Kazuki Takamatsu<\/a>‘s work – which I’ve always wanted to see realised in 3D.<\/p>\n

Here’s a sample (image resized and used without permission):<\/p>\n

\"depth\"<\/a><\/p>\n

Fabian Januszewski has written a neat autostereogram generator<\/a> which is conveniently included in the Ubuntu package repositories<\/a>. I used “stereograph” to generate a basic autostereogram of the above depth map:<\/p>\n

\"stereogram\"<\/a><\/p>\n

Generating stereo pairs (and an anaglyph) was a bit more work. There seemed to be heaps of programs that would generate a depth map given a stereo pair, but I couldn’t find anything that would generate a stereo pair from a depth map (the displace<\/a> map in the GIMP<\/a> seemed like it should work, but I couldn’t get it to…)<\/p>\n

I knew that simply remapping the source depth map pixels to stereo images would result in gaps, but I was sure that a simple gap-filling algorithm could be used (rather than having to use splatting<\/a> or other complex point cloud<\/a> rendering techniques).<\/p>\n

Here are the results of my first pass at stereo pair generation:<\/p>\n

\"stereo\"<\/a><\/p>\n

There are a few good guides (such as those by Gale Rhodes<\/a> and Boris Starosta<\/a>) on how to view cross stereo pairs such as the above image. (When you can see it in 3D, it’s pretty striking.)<\/p>\n

One of the biggest problems I encountered with gap-filling was that anti-aliased edges represent erroneous depth data. If you imagine a depth map with a white line on a black background, the white line is near the camera and the black background is far away. When the line is anti-aliased, the grey pixels falsely imply that there are small dots floating somewhere between the (white) object and the (black) background.<\/p>\n

Unfortunately, most of the depth maps that I found online “featured” anti-aliased edges. Fortunately, I should be able to disable anti-aliasing when generating my own depth maps. (Although this apparently isn’t an option<\/a> when using Inkscape<\/a>.)<\/p>\n

The stereo pair looked good enough to attempt generating an anaglyph. I came across this GIMP script (by Steph Parker<\/a>) which made it very easy to do. Here are the results (with the original depth map included along with the red and blue layers):<\/p>\n

\"anaglyph\"<\/a><\/p>\n

I’ve ordered some 3D glasses<\/a>, but they haven’t yet arrived. So I’m not sure if the above image looks alright. (If you have a pair of red\/blue 3D glasses, please let me know how the above image looks in 3D!)<\/p>\n

After reading more about anaglyphs, I’d like to write a script that generates colour (rather than monochromatic) anaglyphs. It looks a bit more involved, but should be worth the effort.<\/p>\n

I hope you enjoyed this write-up! No doubt I will post more about stereographics at some point in future. \ud83d\ude09<\/p>\n","protected":false},"excerpt":{"rendered":"

I’ve recently been working on various stereographics in preparation for the upcoming Summer exhibition (opening next Tuesday at Little Creatures). I’ve previously mentioned my love for stereographics, but I wanted to write a post with a bit more detail… I’m technically inclined, mostly work in digital media, and advocate open source software. Accordingly, when trying … Continue reading “Stereograms and anaglyphs”<\/span><\/a><\/p>\n","protected":false},"author":67,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[1],"tags":[],"jetpack_featured_media_url":"","jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paLsRH-BH","_links":{"self":[{"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/posts\/2337"}],"collection":[{"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/users\/67"}],"replies":[{"embeddable":true,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/comments?post=2337"}],"version-history":[{"count":20,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/posts\/2337\/revisions"}],"predecessor-version":[{"id":2361,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/posts\/2337\/revisions\/2361"}],"wp:attachment":[{"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/media?parent=2337"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/categories?post=2337"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nick.onetwenty.org\/index.php\/wp-json\/wp\/v2\/tags?post=2337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}