<div dir="ltr">What information do you have? I don't understand what you are trying to do. If you are trying to find the camera position from matched keypoints on different images you need to perform homography and have >= 4 matching keypoints. <a href="http://en.wikipedia.org/wiki/Homography_%28computer_vision%29">http://en.wikipedia.org/wiki/Homography_%28computer_vision%29</a><div><br></div><div>If you are trying to find the distance to a single point you need the camera position and where the X, Y of the point in at least 2 frames. Take a look at epipolar lines, and well as the homography link. There is also an excellent book called multi-view geometry.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 30, 2015 at 3:01 PM, <span dir="ltr"><<a href="mailto:opendronemap-dev-request@lists.osgeo.org" target="_blank">opendronemap-dev-request@lists.osgeo.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Send OpenDroneMap-dev mailing list submissions to<br>
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Today's Topics:<br>
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1. Bundler transformation from image to world coordinates<br>
(Bruno Oliveira)<br>
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Message: 1<br>
Date: Mon, 30 Mar 2015 19:19:02 +0100<br>
From: Bruno Oliveira <<a href="mailto:bruno.manata.oliveira@gmail.com">bruno.manata.oliveira@gmail.com</a>><br>
To: opendronemap-users <<a href="mailto:opendronemap-users@lists.osgeo.org">opendronemap-users@lists.osgeo.org</a>>,<br>
<a href="mailto:opendronemap-dev@lists.osgeo.org">opendronemap-dev@lists.osgeo.org</a><br>
Subject: [OpenDroneMap-dev] Bundler transformation from image to world<br>
coordinates<br>
Message-ID:<br>
<<a href="mailto:CAO-SbSvSd50a_XOoBk80-cJ%2BE09dF_VxNZNrrYYzeshx1gd9VA@mail.gmail.com">CAO-SbSvSd50a_XOoBk80-cJ+E09dF_VxNZNrrYYzeshx1gd9VA@mail.gmail.com</a>><br>
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Hello,<br>
<br>
does anyone know how to do the inverse bundler transform?<br>
This is waht is in the manual (<br>
<a href="http://www.cs.cornell.edu/~snavely/bundler/bundler-v0.3-manual.html" target="_blank">http://www.cs.cornell.edu/~snavely/bundler/bundler-v0.3-manual.html</a>) :<br>
<br>
*P* = *R* * *X* + *t* (conversion from world to camera<br>
coordinates)*p* = -*P* / *P*.z (perspective division)*p*' = *f*<br>
* r(*p*) * *p* (conversion to pixel coordinates)<br>
<br>
<br>
This explains how to transform a world point X to camera coordinates.<br>
<br>
But how do I do the inverse transformation? (for instance, how do I<br>
get thr x point?.....)<br>
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End of OpenDroneMap-dev Digest, Vol 2, Issue 11<br>
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</blockquote></div><br></div>