<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>tomn</author><text>This is really cool.&lt;p&gt;When I first saw this, I re-did the 3D reconstruction as a bundle-adjustment problem, which resulted in this model:&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;misc.tomn.co.uk&amp;#x2F;lightning&amp;#x2F;out.gif&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;misc.tomn.co.uk&amp;#x2F;lightning&amp;#x2F;out.gif&lt;/a&gt;&lt;p&gt;To do this, I found point correspondences between the two images, and set up a model of the two cameras looking at these points. The camera parameters and point positions were then optimised to minimise the reprojection error (the distance between the real positions of the points in the images and the 3D position projected through the camera models).&lt;p&gt;This was implemented using ceres, which is worth a look if you&amp;#x27;re interested in this kind of thing.&lt;p&gt;It took quite a bit of fiddling to make this work, mostly estimating the camera parameters manually by hunting around google maps for landmarks. There&amp;#x27;s not very much data to work with, so the optimisation tends to get lost quite easily without doing this.&lt;p&gt;The results are kind of similar, but it&amp;#x27;s impossible to say which is closer to the real thing. The reprojection error ended up pretty small (mostly a few pixels), but there were some errors that I was unable to reconcile --- likely due to the difficulty of manually estimating point correspondences for a 3D line in space, possible errors in my constraints, lens distortion etc.</text><parent_chain></parent_chain></comment><story><title>3D Lightning (2013)</title><url>http://calculatedimages.blogspot.com/2013/05/3d-lightning.html</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>dang</author><text>Discussed in 2014: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=7702805&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=7702805&lt;/a&gt;</text><parent_chain></parent_chain></comment><story><title>3D Lightning (2013)</title><url>http://calculatedimages.blogspot.com/2013/05/3d-lightning.html</url></story>