This file type is designed to store scalar fields sampled over regular grids (i.e. regular images in 2D, 3D and more) or, by extension, coordinates of tracer particles sampling an underlying density field. The main field format is NDfield, which allows to store any type of data (integer, simple or double precision floating point, ...) over arbitrary sized regular grids or as coordinates of tracer particles.

Available formats:

• -NDfield (Read / Write):
  This is the format used internally in DisPerSE, it is efficient and generic as it can store regular grids or sample particles coordinates indifferently.

• -NDfield_ascii (Read / Write):
  A simple ASCII version of the NDfield format, it is as versatile but data is always considered to be double precision floating point.

• -FITS (Read only):
  Used to read 2D or 3D regular grids of arbitrary dimensions in the popular Flexible Image Transport System (FITS) image format. Also used for HEALPIX tessellations of the sphere.

• -survey_ascii(Read only):
  A simple ASCII format whose main purpose is to easily read coordinates of discretely sampled astrophysical surveys (e.g. such as an SDSS galaxy catalog). Try this if you use spherical coordinates or if distance is measured by redshift for instance.

• -SDL-image (Read only):
  This input format is used to read 2D regular grids encoded in a popular picture format readable by SDL-image library (jpg, png, gif, ...).

• -vtk, vtk_ascii, vti and vti_ascii (Write only):
  These formats are binary and ASCII legacy and XML VTK formats that are readable by several 3D visualization tools, such as VisIt or ParaView for instance.

• -NDnet (Write only):
  Using this format, field files representing tracer particles coordinates can be converted to unstructured networks (use netconv to convert NDnet files to other network formats). Regular grids conversion is not implemented yet due to the huge size of the output network.