[yt-users] quick rendering question

Cameron Hummels chummels at astro.columbia.edu
Wed May 4 09:35:18 PDT 2011


Andrew,

In addition to the steady_north parameter in the camera command, there
is an north_vector parameter, so you can explicitly set what you want
your viewing orientation to be.  I use that to good effect in the
rotate-around-your-object animations.  Good luck!

Cameron

On 05/04/2011 09:34 AM, Sam Skillman wrote:
> Hi Andrew,
>
> I have seen this before, and my recollection was that it was solved by
> first moving to the Camera interface for volume renderings, which is
> documented here:
>
> http://yt.enzotools.org/doc/visualizing/volume_rendering.html#the-camera-interface 
>
> and here:
>
> http://yt.enzotools.org/doc/reference/api/generated/yt.visualization.volume_rendering.camera.Camera.html#yt.visualization.volume_rendering.camera.Camera
>
> and by then using the keyword steady_north=True in the Camera object
> initialization.  This attempts to keep the "up" orientation constant
> while moving the camera during rotations, translations, etc.  This may
> not be necessary, but I have found it useful.
>
> I will also note that there are other benefits to using the Camera
> interface, such as access to the Camera.rotation(theta, n_steps,
> rot_vector=None) function, which returns a series of n_steps snapshots
> rotating through an angle of theta.  Here the optional "rot_vector"
> can be used to specify the vector about which you want to rotate, but
> if none is specified then it uses the current north vector, which is
> probably what you want. 
>
> Let us know if this helps!
>
> Best,
> Sam
>
> On Wed, May 4, 2011 at 9:14 AM, Andrew Davis <andrew.davis at yale.edu
> <mailto:andrew.davis at yale.edu>> wrote:
>
>     Hi folks,
>
>     I'm doing some simple volume rendering, with the end goal to make
>     a movie looking at the central object from a bunch of different
>     angles (just going around in a circle).  When I do the script
>     below, some of the images are rotated 90 degrees from the others
>     -- that is, the correct viewing direction, but just rotated
>     clockwise 90 degrees.  Any thoughts why that would be happening?
>
>     Cheers,
>
>     Andrew
>
>     tf=ColorTransferFunction((mi,ma))
>     tf.add_layers(6,w=0.02)
>     v,c=pf.h.find_max("Density")
>     W = 0.01/pf['pc']
>     Nvec=512
>     for i in range(200):
>        dy=4.*math.pi/199.
>        theta = i * dy
>        yval = math.cos(theta)
>        xval = math.sin(theta)
>        L=[xval,yval,0.]
>        vp=pf.h.volume_rendering(L,W,c,Nvec,tf,whole_box=True)
>        vp.ray_cast()
>        write_bitmap(vp.image,"VolTest_%03d.png" % i)
>
>     *************************************************************
>     **  Andrew J. Davis             andrew.davis at yale.edu
>     <mailto:andrew.davis at yale.edu>      **
>     **  Dept. of Astronomy          203-432-5119 <tel:203-432-5119>  
>                        **
>     **  Yale University             www.astro.yale.edu/adavis
>     <http://www.astro.yale.edu/adavis>   **
>     *************************************************************
>
>
>
>
>
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-- 
Cameron Hummels
PhD Candidate, Astronomy Department of Columbia University
Public Outreach Director, Astronomy Department of Columbia University
NASA IYA New York State Student Ambassador
http://outreach.astro.columbia.edu 
PGP: 0x06F886E3

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