<div dir="ltr">Hi Mohammad,<div><br></div><div>I think you need to add values to the transfer function, as is done in the cookbook:</div><div><a href="http://yt-project.org/doc/cookbook/simple_plots.html#simple-volume-rendering">http://yt-project.org/doc/cookbook/simple_plots.html#simple-volume-rendering</a><br>

</div><div><br></div><div>You can use tf.add_layers, or any of the other tf modifier:</div><div><a href="http://yt-project.org/doc/api/generated/yt.visualization.volume_rendering.transfer_functions.ColorTransferFunction.html#yt.visualization.volume_rendering.transfer_functions.ColorTransferFunction">http://yt-project.org/doc/api/generated/yt.visualization.volume_rendering.transfer_functions.ColorTransferFunction.html#yt.visualization.volume_rendering.transfer_functions.ColorTransferFunction</a><br>

</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Sep 4, 2013 at 10:04 AM, mohammad safarzadeh <span dir="ltr"><<a href="mailto:mtsafarzadeh@gmail.com" target="_blank">mtsafarzadeh@gmail.com</a>></span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi,<div>I am trying to do VR on a halo in my zoom-in region which is a dark matter only sim, but I get a black image when I try this:</div>

<div><br></div><div><p style="margin:0px;font-size:12px;font-family:Helvetica">
L=[1,1,1]</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">W=1/pf["Mpc"]</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">n [16]: mi,ma=region.quantities["Extrema"]("particle_density")[0]</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">In [17]: mi</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">Out[17]: 0.0</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">In [18]: ma</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">Out[18]: 4.5282895435060503e-24</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">In [21]: np.log10(ma)</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">Out[21]: -23.344065811694637</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">mi=-24</p><p style="margin:0px;font-size:12px;font-family:Helvetica">ma=np.log10(ma)</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">tf = ColorTransferFunction((mi,ma))</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">cam=region.pf.h.camera(c, L, W, Npixels, tf,fields=["particle_density"],log_fields=True)</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">ImageArray([[[ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        ..., </p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.]],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">       [[ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        ..., </p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.],</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">        [ 0.,  0.,  0.,  1.]],….</p>
<p style="margin:0px;font-size:12px;font-family:Helvetica;min-height:14px"><br></p>
<p style="margin:0px;font-size:12px;font-family:Helvetica">what is the mistake that I am doing?</p><p style="margin:0px;font-size:12px;font-family:Helvetica"><br></p><p style="margin:0px;font-size:12px;font-family:Helvetica">


-Regards,</p><p style="margin:0px;font-size:12px;font-family:Helvetica">Mohammad</p></div></div>
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<br></blockquote></div><br></div>