MESSENGER Images of Mercury

The Messenger space probe passed by Mercury recently. I hadn’t realized that most of Mercury has never been seen. It’s pretty cool that we get to see images of a new world almost as quickly as the scientists working on it.

That Stupid Bigfoot on Mars

This one has been going around the internet. If you missed it, there’s a rock on Mars near one of the rovers that looks like Bigfoot. The “Bigfoot” thing is pretty silly (although Sasquatch was the first thing I thought when I saw the picture) but that post shows the really cool and huge panorama it came from.

Donald Knuth and LaTeX

I like LaTeX so I found this bit of history about Donald Knuth coming up with the software pretty interesting.

Bioluminescence and Squid Video

I just found out about all these TED talks being online. Pretty handy when you don’t have a TV. This one is about five minutes long and has a bunch of videos of squid, octopuses and things that glow in the depths.

Pulgasari: The North Korean Godzilla

This is another one resulting from not having a TV. Definitely a less than B grade monster movie but it does provide a good comparison to Cloverfield. The story of Kim Jong-Il kidnapping the director and his wife and forcing them to make the thing sounds like a better story than the movie itself (not that it’d take much). For the impatient, there’s decent monster bits around 27:30, 47:30 and 1:03:00.

Soldering Tiny Components

This is a great video tutorial on how to solder tiny electronic components. Really nicely filmed and very closeup. You can really see what’s going on and the guy sure makes it look easy.

NerdKits

A nice idea by a couple college students to sell kits for learning how to use microcontrollers. They “guarantee that you’ll get your first program written and running”. Unfortunately they don’t have a USB version yet. Sort of a homegrown alternative to EasyPic4.

That’s it for now. That was pretty quick and fun to put together so I’ll probably do some more of these in the future. I hope something on there is interesting for other people too.

After seeing it I have to agree, I really enjoyed it and I was on the edge of my seat through the whole thing. I definitely recommend Cloverfield (in the theater if possible). Just one caveat, it’s possible the camera work might disturb anyone with motion sickness although Xiaofen didn’t have any trouble and she gets car sick all the time. I had only seen the (cryptic) trailer and didn’t have any expectations going in and I think that helped so I’m going to leave it at that and follow Wil Wheaton’s example and leave my slightly more detailed analysis in the comments.

Oh if you’re like me and worry that the director is going to stick a little extra on after the credits, there is a little something but it’s not really worth waiting for (only a couple seconds of audio and I’ll link to it below).

Possible spoilers in the comments

After making the WP_MonsterID Wordpress plugin to create a random monster avatar from an assortment of parts for each commenter (based on other people’s code), fruityoaty asked This looks nifty, but how many monster images are available for assigning?

I’d been meaning to calculate this anyway so I did the math and posted it in the comments:

The current part totals are: 17 eyes, 8 hairs, 12 mouths, 15 bodies, 10 legs. That is 244,800 possible combinations. In addition, the body color can range between 20-235 for red, green, and blue. If we count that as 20 distinguishable values for red, green, and blue that adds 8000 possible colors and brings the unique monster count to 2 billion. The only problem is that the algorithm is only using the first 6 digits of the md5 hash of the email which only provides 16 million possible combinations. So I guess the answer is 16 million monsters currently and in the next release I’ll use a few more digits of the hash and increase it to a billion or so. Edit: I did change this so in version 0.3 and later there should be a couple billion possibilities.

Calculating this got me wondering how many unique users it would take before there was likely to be a duplicate monster. For two users it was easy (1 out of 2 billion) but as the number of users increased things got messy since each new monster could match any of the prior monsters. Luckily I remembered enough of my stats class to google for something on calculating the chance of people in a group sharing a birthday.

If you’ve never heard of this problem, stop and take a quick guess for how many people you think it would take for the odds to be better than 50% for two people sharing a birthday. Or as my statistics professor put it, There are twenty-five people in the room will you bet me that no one shares the same birthday?

…

…

Guessed?

Now I know just enough statistics to know betting against a statistics professor is a bad idea but I have to say, at the time, I thought it would have been a fairly good bet. It turns out that I, like most non-statistics professors, underestimated the chance of any two people in a group sharing the same birthday. Actually, if there are 23 people in a room there is a greater than 50% chance that at least two will share a birthday. If there are 47 people in a room, there is a 95% chance that at least one pair share a birthday. This greatly increasing probability occurs because like the monsters each person added to the room can match any of the previous people (the 5th person can match person 1,2,3,4; the 25th person can match person 1,2,3,4,5,6,…,24;…).

All this was interesting in understanding the problem but didn’t really get any closer to finding the probability. Luckily Wikipedia provides an approximation for determining the number of people at a given probability of overlap:

Substituting in 2 billion for 365, results in a probablity of overlap that looks like:

Even with 2 billion monsters there is still a 50% chance of overlap with only 52,000 monsters and a 1 out of 10 chance of overlap with only 20,000 monsters. Most unintuitive to me is that there’s a 99% chance of overlap with only 135,000 monsters. The chances of an overlap really does pile up as the number of already present monsters grow. In the plus side, most normal sized blogs should be safe from monster overlap with only a .1% chance of overlap even with 2000 commenters.

So what does all this mean? Well besides not getting suckered in any birthday betting, it’s a good reminder to be careful about assuming uniqueness among a group just because the chance of a match is rare. For example, if in some application each user was assigned a random key of 4 digits (10000 possible combinations). There would be a greater than 50% chance of overlap after only 1% (117 users) of the keys were assigned.

If any one feels like messing around with the calculations themselves here’s the function in R to calculate the miminimum number of assignments to reach a certain probability of overlap from a total number of possible combinations. I’m sure it would be trivial to convert to any other language. Note that’s natural log not log10. number_assignments=function(total_number,probability_overlap){sqrt(2*total_number*log(1/(1-probability_overlap)))}

I was skimming Simon Willison’s blog (I know his uncle) when I came across this cool idea for automatic avatar generation. Well to tell the truth, I took one look at the title “Visual Security: 9-block IP Identification” and deleted the link from my RSS reader but the next day a link based on that idea came up for generating a unique monster avatar for each user that did catch my interest. After all if it’s got monsters, it has got to be interesting.

Anyway it turns out that Don Park decided to use a commenter’s IP address to generate a random (but persistent for each user) geometric image to associate with each user. This means that without needing external images or sites, each user can have a unique picture associated with them. Even better if several sites were to use the same algorithm for generating the image, the image would stay associated with the user across sites without any cross site communication. Andreas Gohr ran with this idea and decided to generate monsters instead of geometric images and use email addresses instead of IP addresses. So that brings the story here, since these two real programmers had already done all the hard thinking and programming, I thought I would make a quick and dirty Wordpress plugin to incorporate MonsterIDs easily into other blogs. So here is WP_MonsterID. It’s my first real Wordpress plugin so it may not be pretty but it seems to be working OK here (see monsters in the comments below). Edit: If monsters aren’t your thing, I have another plugin using just Don Park’s geometric shapes.

Features

• Monsters
• Dynamically generated avatars for each commenter
• Consistent on any blog
• Gravatar support
• Theme edits no longer necessary

Current Version:

WP_MonsterID v2.12

Installation instructions:

Unzip monsterid.zip. Upload wp_monsterid.php and the monsterid folder. Make sure the monsterid folder is writable. That should be it. Monsters should now appear beside your commenters’ names.

You can add CSS for img.monsterid in your theme’s style.css to adjust the appearance of the images or adjust the size in the MonsterID control panel (your old monsters won’t be deleted until you clear the cache). You can also turn on Gravatar support and clear the MonsterID image cache in the Control Panel.

Tai has translated the installation instructions to Japanese, 5lineas translated them to Spanish, and Dennys has installation tips in Chinese (although these are a bit out of date as of Version 1.0).

Change Log:

• v2.12 05-18-2008:
  • Fixed missing WP 2.5+ builtin avatars
• v2.11 05-17-2008:
  • Fixed recent comment widget double monsters on single pages
  • Added support for WP 2.5+ builtin avatars
• v2.1 03-04-2008:
  • Improved default CSS for MonsterID Recent Comments Widget
  • Added custom CSS editing for widget and MonsterID’s
  • Optimized artistic monsters to only loop through the square region containing the part
• v2.04 2-14-2008:
  • Removed smaller MonsterID option
  • Added Recent Comments (with MonsterID) widget (since default Recent Comment Widget doesn’t provide commenter email)
• v2.02 2-13-2008:
  • Removed monsterid from admin menus when using smaller MonsterIDs
• v2.01 2-12-2008:
  • Add size to img attributes to avoid resizing page as loaded
  • Added option for smaller MonsterIDs on non-post page (like the Recent Comment Widget on the home page)
• v2.0 2-05-2008:
  • Added artistic monsters (thanks to the great artwork of Lemm)
  • Artistic monsters are a bit tough on the server so limited generation time to a max of 5 seconds (unless the user is an admin)
  • Changed to object-oriented monsterid although not completely OOP
  • Added options for greyscale artistic monsters or old fashioned monsters
• v1.02 1-03-2008:
  • Fixed sizing bug (thanks to Daniel)
  • Added size attribute to icons so page doesn’t resize as loaded
  • Removed a couple minor bugs
• v1.01 12-21-2007:
  • Fixed automatic placement in unwanted places (again thanks to Shamus)
  • Switching download link to Wordpress Extends
  • Fixed version numbers in plugin file
• v1.0 12-19-2007:
  • Added option to use show gravatars if they exist and fallback to MonsterID
  • Theme edits no longer necessary (doesn’t hurt if you already did edit it) (This and the previous thanks to Shamus’s nice Wavatar plugin)
  • Cleaned up Options page and error checking
  • Caught possible infinite loop if user selects really dark or light body colors
• v0.61 12-12-2007:
  • Changed to wiki pseudocode version of Mersenne Twister
  • Changed bitshifting to mysql queries since many php versions only have 31 bit integers while Mersenne requires 32
  • Sort part lists to keep things consistent on different servers
• v0.6 12-11-2007:
  • Changed to pure PHP version of Mersenne Twister to allow consistent random numbers across servers
• v0.511-14-2007:
  • Added reminder to clear cache after setting options
  • Added option to switch to white outlines for dark backgrounds
  • Added a few minor parts
• v0.42 8-17-2007:
  • Fixed unintended white background on one pair of legs
• v0.41 8-1-2007:
  • Fixed lower limit in monster_mt_array_rand
  • Readded back.png to parts
• v0.4 7-30-2007:
  • MonsterID’s should now be consistent across servers (by changing rand to mt_rand)
  • Now checks the lightness of body color to make sure monsters aren’t too dark
  • Added some more new monster parts and changed the size slightly on a few older ones
  • Minor bug and WP standards fixes
• v0.3 1-25-2007:
  • Added option to make background transparent. Just set the background color to 0 0 0 for Red, Green and Blue. Note that IE6 does not like transparent png and will turn the background grey.
  • Changed get_bloginfo('url') to get_settings('siteurl') to avoid problems when Options > General > Blog address (URI) is not default
  • Added a few new monster parts and increased the size slightly on a couple of older ones
  • Fixed incorrect link in plugin information
  • Increased length of email hash substring used to generate monster. Should increase possible combinations into the billions.
• v0.2 1-23-2007:
  • Important note: Changed base function from build_monster to monsterid_build_monster for Wordpress function standards (I don’t suppose there’s any other plugins building monsters out there but better safe).
  • Incorporated Adrean’s new extra monster parts and random body coloring and a few parts of my own.
  • Added a random background coloring and the option to set the coloring in the MonsterID menu.
  • Added a test section to the MonsterID menu.
  • Monster building automatically finds monster parts now so the users can add custom monster parts or delete parts they don’t like.
  • Added option to output only image url to monsterid_build_monster: monsterid_build_monster($comment->comment_author_email,$comment->comment_author,false)
• v0.11 1-21-2007:
  • Got off to a pretty inauspicious start with a faulty wordpress page, a couple of immediate small bugs and a faulty file name.
• v0.1 1-21-2007:
  • First version.

For Advanced Users

If you want more control of where MonsterID’s appear, disable the Automatically Add option and find the comments.php of your current theme (it should be in the folder wp-content/themes/[currentThemeName]/). Open it up and look for something similar to foreach ($comments as $comment). Inside this loop there should be code that displays the comment author’s name or metadata like <p class="comment-author"> or <p class="comment-metadata">. Just before all this enter:
<?php if (function_exists("monsterid_build_monster")) {echo monsterid_build_monster($comment->comment_author_email,$comment->comment_author); } ?>

If you would prefer to base the monsters on the commentor’s IP address instead of the commentor’s email just replace $comment->comment_author_email in the above with $comment->comment_author_IP.

Customization:

If you want to customize the monster parts used in your version of WP_MonsterID just go to the wp-contents/monsterid/parts/ folder and delete any parts you don’t like. If you’d like to add your own parts, there is a Gimp file included in that folder containing a layer for each current part which should make constructing new parts easy. Save the new parts following the same conventions bodypartname_initial(s)#.png (e.g. arms_S1.png). If you come up with any good ones, feel free to send them to me and I’ll include them in the package.