[yt-users] is there a limit on image size?

Stuart Levy salevy at illinois.edu
Thu May 28 15:58:15 PDT 2015


If "1/cmax" is failing for a rendered image, that could mean it's all 
black (max pixel=0) ... or maybe that there had been a NaN in it 
somewhere which could likewise break the automatic rescaling.  Are you 
using the rendering interface where you call something like

      cam.snapshot( "image.png" )

to make it save an image?   If so you might try

      rawim = cam.snapshot()

and look at the distribution of raw rendered pixel values in rawim, 
which should be a 3-dimensional array (image size x 4 or something).   
Maybe the fraction of positive values: numpy.sum( rawim > 0 ) / 
float(rawim.size)

Also, Dave, are you rendering using multiple threads?

On 5/28/15 3:52 PM, Dave Semeraro wrote:
>
> Did a bit more experimentation. The error only appears when I run in 
> parallel. Serial runs execute fine but take a long time. So there is 
> some monkey business going on with parallel ray tracing that is 
> triggered by the image size I was using. I am also using a rather 
> large enzo dataset. Thanks for considering the problem.
>
> Dave
>
> *From:*yt-users [mailto:yt-users-bounces at lists.spacepope.org] *On 
> Behalf Of *Nathan Goldbaum
> *Sent:* Thursday, May 28, 2015 2:58 PM
> *To:* Discussion of the yt analysis package
> *Subject:* Re: [yt-users] is there a limit on image size?
>
> On Thu, May 28, 2015 at 12:54 PM, Dave Semeraro 
> <semeraro at tacc.utexas.edu <mailto:semeraro at tacc.utexas.edu>> wrote:
>
>     Helly yt-crowd.
>
>     I am doing some volume rendering in yt and getting some errors
>     when I try to grow the image size. I am trying to write a png
>     image that is 1024 x 1024. I get the following errors:
>
>     image_array.py:229: RuntimeWarning: invalid value encountered in
>     multiply
>
>     np.multiply(self[:, :, :3], 1.0/cmax, out[:, :, :3])
>
> The warning is being triggered here:
>
> https://bitbucket.org/yt_analysis/yt/src/8ad62b62439013a33e3a2b568a5a26b567e93f54/yt/data_objects/image_array.py?at=yt#cl-229 
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__bitbucket.org_yt-5Fanalysis_yt_src_8ad62b62439013a33e3a2b568a5a26b567e93f54_yt_data-5Fobjects_image-5Farray.py-3Fat-3Dyt-23cl-2D229&d=AwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=hgcBC3x6dKFoTrmFmMYYbKNfiHZlGLKliIidd1LwmHI&m=hO5pXcuw5fvvxeGv-5LRShhzRc-WbkaimZIYkj52SZM&s=OH-bab2JlwA0taRkzQRsirFtSlIP1tPzZHqBB6bQN-g&e=>
>
> which I think means cmax is 0.  I'd need to see the full traceback or 
> step through execution in a debugger to figure out why.
>
>     yt_array.py:764: RuntimeWarning: divide by zero encountered in divide
>
>     return YTArray(super(YTArray, self).__rdiv__(lo))
>
>     The largest image I can generate is about 800x 800. It is a nice
>     image too I tell ya. Just wish I could do a bigger one to submit
>     for publication.
>
> There's no limit on the image size for a volume rendering.
>
>     Attached is the script I am using. Any help would be great.
>
>     Thanks,
>
>     Dave Semeraro
>
>
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