<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi Stuart,<div class=""><br class=""></div><div class="">I’ve just read over the source code of PerspectiveCamera, but do not quite understand it… So I wrote anther version of PerspectiveCamera class and pasted it here: <a href="http://paste.yt-project.org/show/WPJ9EYMeYDyb4oPtgC0z/" class="">http://paste.yt-project.org/show/5243/</a></div><div class=""><br class=""></div><div class="">And here’re the test figures of moving camera through the volume:</div><div class=""><br class=""></div><div class=""><a href="http://pbrd.co/1FWWiLE" class="">http://pbrd.co/1FWWiLE</a></div><div class=""><a href="http://pbrd.co/1FWWpH2" class="">http://pbrd.co/1FWWpH2</a></div><div class=""><a href="http://pbrd.co/1FWWGJT" class="">http://pbrd.co/1FWWGJT</a></div><div class=""><br class=""></div><div class="">Also, in the YT-3 dev version there’re SphericalCamera and StereoSphericalCamera, which will generate 360 degree dome views.</div><div class=""><br class=""></div><div class="">PS. I’m not sure whether there’ll be someone who can fix PerspectiveCamera, or I’ll create a PR…</div><div class=""><br class=""></div><div class="">Best wishes,</div><div class=""><br class=""><div class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">--</div><div class="">Suoqing JI</div><div class="">Ph.D Student</div><div class="">Department of Physics</div><div class="">University of California, Santa Barbara</div><div class="">CA 93106, USA</div></div></div></div></div>
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<br class=""><div><blockquote type="cite" class=""><div class="">On Dec 4, 2014, at 1:08 PM, Nathan Goldbaum <<a href="mailto:nathan12343@gmail.com" class="">nathan12343@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">Hi Stuart,<br class=""><br class="">Looking at the PerspectiveCamera source with "hg blame", it looks like it has seen only superficial changes since January 2013. I bet what you're seeing is due to something else changing in the volume rendering interface underneath it.<div class=""><br class=""></div><div class="">FWIW, the PerspectiveCamera does have tests: </div><div class=""><br class=""></div><div class=""><a href="https://bitbucket.org/yt_analysis/yt/src/5cd6764df8f3fbb981eefa5f19ee9f98b0ed61f6/yt/visualization/volume_rendering/tests/test_vr_cameras.py?at=yt#cl-91" class="">https://bitbucket.org/yt_analysis/yt/src/5cd6764df8f3fbb981eefa5f19ee9f98b0ed61f6/yt/visualization/volume_rendering/tests/test_vr_cameras.py?at=yt#cl-91</a></div><div class=""><br class=""></div><div class="">But the tests only check to make sure the camera works without crashing, and does not verify that the answer is correct. It's entirely possible something has broken in the last two years.</div><div class=""><br class=""></div><div class="">-Nathan</div><br class=""><div class="gmail_quote">On Thu Dec 04 2014 at 1:01:51 PM Michael Zingale <<a href="mailto:michael.zingale@stonybrook.edu" class="">michael.zingale@stonybrook.edu</a>> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">Hi Stuart, I've had a similar experience and haven't looked back at it in about 6 mos. I was planning on waiting until the new renderer is in, and then I was going to try again.<div class=""><br class=""></div><div class="">Mike</div></div><div class="gmail_extra"></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Dec 4, 2014 at 2:55 PM, Stuart Levy <span dir="ltr" class=""><<a href="mailto:salevy@illinois.edu" target="_blank" class="">salevy@illinois.edu</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I know it's being rewritten, thanks to Sam and Cameron and others, but I'm hoping to use some sort of perspective camera for volume rendering. (What I'll eventually want is the dome camera which I know also exists, but wanted to start with a simpler plane-projection perspective camera.)<br class="">
<br class="">
What I get: plausible images from the default orthographic Camera, but reliably blank images from PerspectiveCamera.<br class="">
<br class="">
If I extract the sampler rays from PerspectiveCamera and plot them, they always seem to point in the hemisphere away from the given center point. If I change the sign of Z width, the viewpoint is put on the opposite side of the data region, and the rays still point away from it.<br class="">
Also they're extremely short, like .001 or so of the distance from the viewpoint to the center point - much too short to intersect anything if the viewpoint is outside of the data volume.<br class="">
<br class="">
If I hack the sampler vectors in PerspectiveCamera to (a) reverse their direction and (b) make them many times longer, I do see something.<br class="">
<br class="">
I don't know whether I'm passing nonsense parameters to PerspectiveCamera, or whether its current code is really not right...?<br class="">
<br class="">
A sample program, which contains its own replacement for Camera.snapshot() that allows for tweaking PerspectiveCamera rays, is in:<br class="">
<br class="">
<a href="http://paste.yt-project.org/show/5240/" target="_blank" class="">http://paste.yt-project.org/<u class=""></u>show/5240/</a><br class="">
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</blockquote></div><br class=""><br clear="all" class=""><div class=""><br class=""></div></div><div class="gmail_extra">-- <br class=""><div class=""><div class="">Michael Zingale</div><div class="">Associate Professor</div><div class=""><br class=""></div><div class="">Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY 11794-3800</div><div class=""><i class="">phone</i>: 631-632-8225</div><div class=""><i class="">e-mail</i>: <a href="mailto:Michael.Zingale@stonybrook.edu" target="_blank" class="">Michael.Zingale@stonybrook.edu</a></div><div class=""><i class="">web</i>: <a href="http://www.astro.sunysb.edu/mzingale" target="_blank" class="">http://www.astro.sunysb.edu/mzingale</a></div></div>
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