<meta http-equiv="Content-Type" content="text/html; charset=utf-8">Hi Suoqing,<br><br><div>I agree, this would be great to add, and we can thread it through to the new VR framework once it gets merged.</div><div><br></div><div>Great job!</div><br><div class="gmail_quote">On Fri Dec 05 2014 at 3:06:15 PM Stuart Levy <<a href="mailto:salevy@illinois.edu">salevy@illinois.edu</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Wow, this is wonderful! I was thinking to just rewrite it, which
seemed easier than trying to understand the existing code, but
you've done it so quickly - thank you!<br>
<br>
I haven't had a chance to try your new PerspectiveCamera yet but
will do. It looks like a perfectly sensible computer-graphics
camera, with field-of-view equal to 2*atan(0.5*width[0]/width[2])
and 2*atan(0.5*width[1]/width[2]).<br>
<br>
thanks again</div><div bgcolor="#FFFFFF" text="#000000"><br>
<br>
Stuart</div><div bgcolor="#FFFFFF" text="#000000"><br>
<br>
<div>On 12/5/14 1:07 AM, Suoqing JI wrote:<br>
</div>
<blockquote type="cite">
Hi Stuart,
<div><br>
</div>
<div>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/" target="_blank">http://paste.yt-project.org/show/5243/</a></div>
<div><br>
</div>
<div>And here’re the test figures of moving camera
through the volume:</div>
<div><br>
</div>
<div><a href="http://pbrd.co/1FWWiLE" target="_blank">http://pbrd.co/1FWWiLE</a></div>
<div><a href="http://pbrd.co/1FWWpH2" target="_blank">http://pbrd.co/1FWWpH2</a></div>
<div><a href="http://pbrd.co/1FWWGJT" target="_blank">http://pbrd.co/1FWWGJT</a></div>
<div><br>
</div>
<div>Also, in the YT-3 dev version there’re
SphericalCamera and StereoSphericalCamera, which will generate
360 degree dome views.</div>
<div><br>
</div>
<div>PS. I’m not sure whether there’ll be someone who can
fix PerspectiveCamera, or I’ll create a PR…</div>
<div><br>
</div>
<div>Best wishes,</div>
<div><br>
<div>
<div style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word">
<div style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word">
<div style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word">
<div style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word">
<div>--</div>
<div>Suoqing JI</div>
<div>Ph.D Student</div>
<div>Department of Physics</div>
<div>University of California, Santa Barbara</div>
<div>CA 93106, USA</div>
</div>
</div>
</div>
</div>
</div>
<br>
<div>
<blockquote type="cite">
<div>On Dec 4, 2014, at 1:08 PM, Nathan Goldbaum
<<a href="mailto:nathan12343@gmail.com" target="_blank">nathan12343@gmail.com</a>>
wrote:</div>
<br>
<div>Hi Stuart,<br>
<br>
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><br>
</div>
<div>FWIW, the PerspectiveCamera does have
tests: </div>
<div><br>
</div>
<div><a href="https://bitbucket.org/yt_analysis/yt/src/5cd6764df8f3fbb981eefa5f19ee9f98b0ed61f6/yt/visualization/volume_rendering/tests/test_vr_cameras.py?at=yt#cl-91" target="_blank">https://bitbucket.org/yt_analysis/yt/src/5cd6764df8f3fbb981eefa5f19ee9f98b0ed61f6/yt/visualization/volume_rendering/tests/test_vr_cameras.py?at=yt#cl-91</a></div>
<div><br>
</div>
<div>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><br>
</div>
<div>-Nathan</div>
<br>
<div class="gmail_quote">On Thu Dec 04 2014 at 1:01:51 PM
Michael Zingale <<a href="mailto:michael.zingale@stonybrook.edu" target="_blank">michael.zingale@stonybrook.edu</a>>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">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><br>
</div>
<div>Mike</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Dec 4, 2014 at 2:55
PM, Stuart Levy <span dir="ltr"><<a href="mailto:salevy@illinois.edu" target="_blank">salevy@illinois.edu</a>></span>
wrote:<br>
<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>
<br>
What I get: plausible images from the default
orthographic Camera, but reliably blank images
from PerspectiveCamera.<br>
<br>
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>
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>
<br>
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>
<br>
I don't know whether I'm passing nonsense
parameters to PerspectiveCamera, or whether its
current code is really not right...?<br>
<br>
A sample program, which contains its own
replacement for Camera.snapshot() that allows
for tweaking PerspectiveCamera rays, is in:<br>
<br>
<a href="http://paste.yt-project.org/show/5240/" target="_blank">http://paste.yt-project.org/show/5240/</a><br>
<br>
<br>
<br>
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</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
</div>
<div class="gmail_extra">-- <br>
<div>
<div>Michael Zingale</div>
<div>Associate Professor</div>
<div><br>
</div>
<div>Dept. of Physics &
Astronomy • Stony Brook University • Stony
Brook, NY 11794-3800</div>
<div><i>phone</i>: 631-632-8225</div>
<div><i>e-mail</i>: <a href="mailto:Michael.Zingale@stonybrook.edu" target="_blank">Michael.Zingale@stonybrook.edu</a></div>
<div><i>web</i>: <a href="http://www.astro.sunysb.edu/mzingale" target="_blank">http://www.astro.sunysb.edu/mzingale</a></div>
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