[yt-dev] volume rendering orientation

[Nathan Goldbaum]

Once the bug you mention gets fixed (seems like an straightforward patch
for write_png?), we could probably add this as an answer test.  We do some
image comparison tests already in the tests for PlotWindow plots.


On Thu, Jul 31, 2014 at 10:57 AM, Michael Zingale <
michael.zingale at stonybrook.edu> wrote:

> To help with understanding the volume rendering orientation issues, here's
> a self-contained test that I've been using.
>
> This puts a single cube on +x, two cubes on +y, and three cubes on +z.
>  North is set to +z.
>
> The save_annotated image has the right orientation and handedness.
>
> The write_png image is upside down.
>
> I found this data very helpful in understanding and testing orientations.
>
> Mike
>
>
> ------
>
>
> import pylab
> import yt
> import numpy as np
>
> N = 128
>
> xmin = ymin = zmin = -1.0
> xmax = ymax = zmax = 1.0
>
> arr = np.zeros((N,N,N), dtype=np.float64)
> arr[:,:,:] = 1.e-4
>
> bbox = np.array([ [xmin, xmax], [ymin, ymax], [zmin, zmax] ])
>
> # coordinates -- in the notation data[i, j, k]
> x = (np.arange(N) + 0.5)*(xmax - xmin)/N + xmin
> y = (np.arange(N) + 0.5)*(ymax - ymin)/N + ymin
> z = (np.arange(N) + 0.5)*(zmax - zmin)/N + zmin
>
> x3d, y3d, z3d = np.meshgrid(x, y, z, indexing="ij")
>
> # single cube on +x
> xc = 0.75
> dx = 0.05
> idx = np.logical_and(np.logical_and(x3d > xc-dx, x3d < xc+dx),
>                      np.logical_and(np.logical_and(y3d > -dx, y3d < dx),
>                                     np.logical_and(z3d > -dx, z3d < dx)) )
>
> arr[idx] = 1.0
>
>
> # two cubes on +y
> dy = 0.05
> for yc in [0.65, 0.85]:
>
>     idx = np.logical_and(np.logical_and(y3d > yc-dy, y3d < yc+dy),
>                          np.logical_and(np.logical_and(x3d > -dy, x3d <
> dy),
>                                         np.logical_and(z3d > -dy, z3d <
> dy)) )
>
>     arr[idx] = 0.8
>
> # three cubes on +z
> dz = 0.05
> for zc in [0.5, 0.7, 0.9]:
>
>     idx = np.logical_and(np.logical_and(z3d > zc-dz, z3d < zc+dz),
>                          np.logical_and(np.logical_and(x3d > -dz, x3d <
> dz),
>                                         np.logical_and(y3d > -dz, y3d <
> dz)) )
>
>     arr[idx] = 0.6
>
>
>
>
> data = dict(Density = arr)
> ds = yt.load_uniform_grid(data, arr.shape, bbox=bbox)
>
>  import yt.visualization.volume_rendering.api as vr
>
> c = np.array([0, 0, 0])
> L = np.array([1.0, 1.0, 1.0])
> W = 2.0*ds.domain_width
> N = 720
>
> north = np.array([0, 0, 1])
>
> tf = vr.ColorTransferFunction((0.1,1.0))
> tf.sample_colormap(1.0, 0.05, colormap="coolwarm")
> tf.sample_colormap(0.8, 0.05, colormap="coolwarm")
> tf.sample_colormap(0.6, 0.05, colormap="coolwarm")
>
> cam = vr.Camera(c, L, W, N, transfer_function=tf,
>                 north_vector = north,
>                 ds=ds, fields=[('gas', 'Density')],
>                 log_fields=[False])
>
>
> im = cam.snapshot()
> nim = cam.draw_domain(im)
>
> nim.write_png("test.png")
>
> cam.save_annotated("test_annotated.png", nim)
>
> ------
>
>
> --
> Michael Zingale
> Associate Professor
>
> Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
> 11794-3800
> *phone*:  631-632-8225
> *e-mail*: Michael.Zingale at stonybrook.edu
> *web*: http://www.astro.sunysb.edu/mzingale
>
> _______________________________________________
> yt-dev mailing list
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>
>
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