[Python-apps-team] Bug#478960: mayavi2: interpolation produces fake transparency effects

[Francesco Poli]

Package: mayavi2
Version: 2.1.1-2
Severity: normal


Hi!

I noticed an issue with the interpolation feature.

Please note that I've recently upgraded mayavi2 from version 2.1.1-2 to
version 2.1.1-2+b1, but I've seen the same issue with version 2.1.1-2,
as well.

I've seen the issue happen with basically any data source.
The test case I prepared is based on a simple (legacy) VTK data
file ('fakehurr_merid.vtk') generated by a Fortran program
('gen_fakehurr.f').

  $ tar xzf mayavi2-interpolation-bug-test.tar.gz
  $ ls
  fakehurr_merid.vtk  gen_fakehurr.f  mayavi2-interpolation-bug-test.tar.gz
  $ mayavi2 -d fakehurr_merid.vtk

The main window shows up, with a data source already loaded.

 * for menus, select Visualize -> Modules -> Surface
 * in the MayaVi pane, double-click on Surface
 * in the dialog window, check Interpolate scalars before mapping
 * click on the OK button

A nice visualization is shown, with very smooth colored areas.

 * in the TVTK Scene 1 pane, click on the Obtain an isometric view button

There's an area on the left where the interpolation seems to produce
a strange fake transparency effect (as shown in the attached PNG image).
Disabling the interpolation makes this defect vanish (but produces a
less convincing visualization).

What's wrong?
I think this is a bug.



-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.24-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages mayavi2 depends on:
ii  libc6                        2.7-10      GNU C Library: Shared libraries
ii  python                       2.5.2-1     An interactive high-level object-o
ii  python-central               0.6.6       register and build utility for Pyt
ii  python-enthought-traits      2.0.4-2     Manifest typing and reactive progr
ii  python-enthought-traits-ui   2.0.4-2     User interface related modules for
ii  python-numpy                 1:1.0.4-7   Numerical Python adds a fast array
ii  python-pkg-resources         0.6c8-3     Package Discovery and Resource Acc
ii  python-vtk                   5.0.4-1+b1  Python bindings for VTK
ii  python-wxgtk2.6              2.6.3.2.2-2 wxWidgets Cross-platform C++ GUI t
ii  python2.5                    2.5.2-3     An interactive high-level object-o

mayavi2 recommends no packages.

-- no debconf information
-------------- next part --------------
A non-text attachment was scrubbed...
Name: mayavi2-interpolation-bug-test.tar.gz
Type: application/x-gzip
Size: 34697 bytes
Desc: not available
Url : http://lists.alioth.debian.org/pipermail/python-apps-team/attachments/20080502/ffe938de/attachment-0001.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: foo.png
Type: image/png
Size: 72887 bytes
Desc: not available
Url : http://lists.alioth.debian.org/pipermail/python-apps-team/attachments/20080502/ffe938de/attachment-0001.png