import pylab
from yt.mods import *
arr = np.random.random(size=(64,64,64))
data = dict(Density = arr)
bbox = np.array([[-1.5, 1.5], [-1.5, 1.5], [-1.5, 1.5]])
pf = load_uniform_grid(data, arr.shape)
import yt.visualization.volume_rendering.api as vr
c = (pf.domain_right_edge + pf.domain_left_edge)/2.0
L = np.array([-0.0, -1.0, -1.0])
W = 2.0*pf.domain_width
N = 720
tf = vr.ColorTransferFunction((0.0,1.0))
tf.add_layers(10, 0.1)
cam = vr.Camera(c, L, W, N, transfer_function=tf, pf=pf, fields=[('gas', 'Density')], log_fields=[False])
rot_vector=[0.0,0.0,1.0]
cam.rotate(2*np.pi/6., rot_vector=rot_vector)
im = cam.snapshot()
nim = cam.draw_domain(im)
pylab.imshow(nim)
pylab.savefig("test.png")
This generates a simple cube with the domain drawn, and it looks as I expect. If I change Camera to PerspectiveCamera, but leave everything else unchanged, I get a blank image.