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CHAPTER 11. OUTPUT AND VISUALIZATION
11.1.3
94
VTK Output: vtk data format
VTK (from the Visualization ToolKit format) output follows essentially the same conventions used for
the .dbl or .flt outputs. Single or multiple VTK files can be written by specifying either single file or
multiple files in your pluto.ini and data values are always written using single precision with byte
order set to big endian.
The mesh topology uses a rectilinear grid format for CARTESIAN or CYLINDRICAL geometry while
a structured grid format is employed for POLAR or SPHERICAL geometries. Data is written with the
CELL DATA attribute and grid nodes (or vertices) are used to store the mesh.
The following symbolic constants (§2.3) can be used to control some options of the output .vtk files:
• VTK TIME INFO: when set to YES, time information will be added to the header section of the
.vtk file. Beware that standard VTK files do not have a specific construct for adding time information and, by doing so, this information will be available only to the VisIt visualisation software
(see §11.3.5) which implements a convention where CYCLE and TIME values can be specified as
FieldData in the file. If you’re using Paraview or other visualisation software different from VisIt,
enabling this option will most likely result in a software crash.
• VTK VECTOR DUMP: by default, all flow quantities (e.g. density, or the x1 component of velocity)
are written with “scalar” attribute as they are. However, by setting VTK VECTOR DUMP to YES,
vector fields (such as velocity and magnetic field) can be saved with the “vector” attribute and
their components are automatically transformed to Cartesian.
See also Table B.1.
If a VTK file is written to disk, the log file vtk.out is updated in the same manner as dbl.out or flt.out.
Default: By default, all variables except staggered magnetic field components (if any) are written.
11.1.4
ASCII Output: tab Data format
The tab format may be used for one dimensional data or relatively small two dimensional arrays in
serial mode only. We warn that this output is not supported in parallel mode. The output consists in
multi-column ascii files named data.nnnn.tab of the form:
.
.
.
x(i)
.
.
.
.
.
.
y(j)
.
.
.
.
.
.
var1(i,j)
.
.
.
.
.
.
var2(i,j)
.
.
.
.
.
.
var3(i,j)
.
.
.
.
.
.
...
.
.
.
where the index j changes faster and a blank records separates blocks with different i index.
Default: By default, all variables except staggered magnetic field components (if any) are written.
11.1.5
Graphic Output: ppm and png data formats
PLUTO allows to take two-dimensional slices in the x1 x2 , x1 x3 or x2 x3 planes and save the results
as color ppm or png images. The Portable Pixmap (ppm) format is quite inefficient and redundant although easy to write on any platform since it does not require additional libraries. The Portable Network
Graphics (png) is a bitmap image format that employs lossless data compression. It requires libpng to be
installed on your system.
Different images are associated with different variables and can have different sets of attributes defined by the Image structure. An image structure has the following customizable elements:
• slice plane: a label (X12 PLANE, X13 PLANE, X23 PLANE) setting the slicing 2D plane.
• slice coord: a real number specifying the coordinate orthogonal to slice plane.
• max,min: the maximum and minimum values to which the image is scaled to. If max=min autoscaling is used;