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	<title>BlackHC's Adventures in the Dev World &#187; CCD</title>
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		<title>Seminar about Motion Retargeting</title>
		<link>http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/</link>
		<comments>http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/#comments</comments>
		<pubDate>Fri, 30 Jan 2009 23:32:20 +0000</pubDate>
		<dc:creator>BlackHC</dc:creator>
				<category><![CDATA[Coding]]></category>
		<category><![CDATA[Maths]]></category>
		<category><![CDATA[University]]></category>
		<category><![CDATA[CCD]]></category>
		<category><![CDATA[Inverse Kinematics]]></category>
		<category><![CDATA[Macros]]></category>
		<category><![CDATA[Motion Retargeting]]></category>
		<category><![CDATA[Particle IK]]></category>
		<category><![CDATA[PowerPoint]]></category>
		<category><![CDATA[Spore]]></category>
		<category><![CDATA[VBA]]></category>

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		<description><![CDATA[<a href="http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/" title="Seminar about Motion Retargeting"></a>Two weeks ago I had to give a presentation about Motion Retargeting, which I want to share with you now. I created it due to me attending a seminar about the latest developments in Computer Graphics at university and my &#8230;<p class="read-more"><a href="http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/">Read more &#187;</a></p>]]></description>
			<content:encoded><![CDATA[<a href="http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/" title="Seminar about Motion Retargeting"></a><p><a href="http://blog.blackhc.net/wp-content/uploads/2009/01/creatureanimationwb.gif"><img class="alignright size-full wp-image-300" title="creatureanimationwb" src="http://blog.blackhc.net/wp-content/uploads/2009/01/creatureanimationwb.gif" alt="creatureanimationwb" width="147" height="110" /></a>Two weeks ago I had to give a presentation about Motion Retargeting, which I want to share with you now.<br />
I created it due to me attending a seminar about the latest developments in Computer Graphics at university and my presentation was about the Siggraph '08 paper "<a href="http://www.chrishecker.com/images/c/cb/Sporeanim-siggraph08.pdf" target="_blank">Real-time Motion Retargeting to Highly Varied User-Created Morphologies</a>" from Chris Hecker et al.<br />
You can check it out on <a href="http://www.chrishecker.com/Real-time_Motion_Retargeting_to_Highly_Varied_User-Created_Morphologies" target="_blank">Chris Hecker's homepage</a> - his website also contains a bunch of other really cool articles and presentations from various conferences, so it certainly is worth taking a look at it.</p>
<p>I've also sifted through quite a lot of IK papers and lectures for my presentation to understand the later part about the IK solver in Spore and I've found a few links that are a nice read:</p>
<ul>
<li><a href="http://www.chrishecker.com/Inverse_Kinematics" target="_blank">Chris Hecker's talk</a> about IK is a nice introduction (you also get an audiostream which is nice, too).</li>
<li><a href="http://ir.lib.sfu.ca/handle/1892/7119" target="_blank">Chris Welman's Master Thesis</a> is nice for reading about some of the common methods to solve IK problems.</li>
<li><a href="http://graphics.ucsd.edu/courses/cse169_w05/index.html" target="_blank">Steve Rotenberg's Computer Animation</a> course is awesome - the slides about IK are nice, but the ones about locomotion are just awesome<a class="annotation" title="they really really are!" href="javascript:;"><strong>&#180;</strong></a>!</li>
<li>Particle IK and particle physics in games are related a lot (the constraint solver is pretty much the same) and for a nice read I can recommend <span lang="EN-US"><a href="http://www.teknikus.dk/tj/gdc2001.htm" target="_blank">Thomas Jakobsen's Advanced Character Physics</a>.</span></li>
<li><span lang="EN-US"><a href="http://www.pixar.com/companyinfo/research/pbm2001/" target="_blank">Pixar's Physically Based Modelling</a> course from 2001 is also nice to get going with physics again - it also explains everything you need to understand the idea behind ODE solvers in rigid body simulations  and also has a very nice explanation of stiffness in ODEs.</span></li>
<li><span lang="EN-US"><a href="http://books.google.com/books?id=2anZacrFaxoC&amp;printsec=frontcover" target="_blank">Principles of Animal Locomotion</a> is a very neat book that is about, well, the principles of animal locomotion, which I have read a bit thanks to Google books and it certainly is quite interesting.</span></li>
<li><span lang="EN-US"><a href="http://www.robotom.de/robi.htm" target="_blank">Numerical Robot Kinematics Based on Stochastic and Molecular Simulation Methods</a> is interesting, too, just to see what's possible with particle IK</span></li>
</ul>
<p>Ive created a huge PowerPoint presentation for my seminar  <img src='http://blog.blackhc.net/wp-includes/images/smilies/icon_smile.gif' alt=':-)' class='wp-smiley' />  It includes a few videos (thanks again to Chris Hecker for uploading them and replying to my emails incredibly fast <a class="annotation" title="he replied to each and every one of them within 20 minutes, which is crazy fast, if you're used to university communication ;-)" href="javascript:;"><strong>&#180;</strong></a>) and two <strong>awesome</strong> IK solvers that I've implemented with VBA macros<a class="annotation" title="VBA is horrible BTW" href="javascript:;"><strong>&#180;</strong></a> to show how CCD and Particle IK solvers work.</p>
<p>You can find a zip with all the videos and high resolution images <a href="http://blog.blackhc.net/wp-content/uploads/2009/01/MotionRetargeting.zip">here </a>(includes both a PPT 2003 file and a 2007 file). I've also uploaded a small version without videos, macros as PPT 2003 file <a href="http://blog.blackhc.net/wp-content/uploads/2009/01/motionretargetingcompat.ppt">here</a>, if you don't feel like downloading the 23 MB .zip file.</p>
<p>Here's a YouTube video of the two IK solvers:</p>
<p><a href="http://blog.blackhc.net/2009/01/seminar-about-motion-retargeting/"><em>Click here to view the embedded video.</em></a></p>
<div class="expandable"><a class="expandable_link" href="javascript:blackhc_replacements_togglediv('blackhc_expandable_1');">Click to expand &#187;</a>
<div class="expandable_text" name="blackhc_expandable_1" id="blackhc_expandable_1" style="display:none">The CCD solver usually works by solving one bone per inner iteration - I only added a max delta angle to create smooth animations (same for the max delta length in the Particle IK solver).</p>
<p>It seems as if the CCD solver could converge faster if it randomly chose the first joint instead of starting with the end effector joint in every outer iteration.</p></div>
<p></div>
<p>I've exported the code into an additional IK Playground presentation which contains just one slide and the two IK solvers with the setup you see in the video above. You can find the PPT 2003 version of it <a href="http://blog.blackhc.net/wp-content/uploads/2009/01/ikplayground.ppt">here</a> and the 2007 one <a href="http://blog.blackhc.net/wp-content/uploads/2009/01/ikplayground.pptm">here</a>.</p>
<p>I've zipped up the macros <a href="http://blog.blackhc.net/wp-content/uploads/2009/01/mr-pptmacros.zip">here</a> if you want to use them in your own slides. I've also written a handy VBA form that allows one to edit everything more easily (the macros are hardly documented though, but if anyone really wants to use them and runs into problems - you can always drop me a line or two in a comment <img src='http://blog.blackhc.net/wp-includes/images/smilies/icon_smile.gif' alt=':)' class='wp-smiley' /> )</p>
<p style="text-align: center;">
<div id="attachment_302" class="wp-caption aligncenter" style="width: 501px"><a href="http://blog.blackhc.net/wp-content/uploads/2009/01/iksolvertool1.jpg"><img class="size-large wp-image-302" title="iksolvertool1" src="http://blog.blackhc.net/wp-content/uploads/2009/01/iksolvertool1-1024x622.jpg" alt="The IK Solver Tool Form" width="491" height="298" /></a><p class="wp-caption-text">The IK Solver Tool Form</p></div>
<p>BTW I'm not sure you know about it<a class="annotation" title="I only learned of it by chance" href="javascript:;"><strong>&#180;</strong></a>, but <a href="http://www.blender.org/">Blender</a> contains an awesome video editor - the UI needs some time to get used to, but the online documentation has improved a lot and with it, it works like a charm. Blender also supports some <a href="http://wiki.blender.org/index.php/Manual/Sequence_Plugins">pretty professional filters</a>, so it's going to be my video editing tool of choice from now on.</p>
<p>Cheers,<br />
Andreas</p>
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