[yt-dev] Issue #1183: "Failed to split grids" when volume rendering GIZMO data (yt_analysis/yt)

[Sanghyuk Moon]

New issue 1183: "Failed to split grids" when volume rendering GIZMO data
https://bitbucket.org/yt_analysis/yt/issues/1183/failed-to-split-grids-when-volume

Sanghyuk Moon:

I encountered a problem trying to volume render GIZMO snapshot.
The other visualizations such as `SlicePlot` and `ProjectionPlot` were all successful. But everytime I try to create `Camera` for the volume rendering, I got the message "*Failed to split grids.*" and returned `ImageArray` is just black image. Has anyone resolved this issue?

Here's the code I typed.

```
#!python
tf = yt.ColorTransferFunction((-2, 1))
cam = ds.camera([2.0, 0.0, 2.0], [-0.1, 0.0, -0.1], 0.10, 256, tf,
               fields=('gas','density'),log_fields=[True],no_ghost=False)

tf.add_layers(4, 0.01, col_bounds = [-1,0], colormap = 'RdBu_r')
cam.snapshot("v1.png", clip_ratio=6.0)
```
And here's the output

```
#!python

ImageArray([[[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]],

       [[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]],

       [[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]],

       ..., 
       [[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]],

       [[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]],

       [[ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        ..., 
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.],
        [ 0.,  0.,  0.,  1.]]]) (dimensionless)
```