Module category: IO

• WriteVolume
  • Parameters
  • Input Ports
  • Examples

WriteVolume

This module writes volume data files from volumetric packed RGBA, vector, or multi-channel scalar data on uniform grids.

For more information about Volume Rendering see COVISE VR & CE User's Guide, Appendix "Volume Rendering in Covise"

Files of the following 3D volume data formats can be written:

• .rvf: Data format for 'raw volume data'. This format can easily be created by hand from any voxel data array on disk by just adding the appropriate header: 3 x 2 Bytes (little endian) = volume width/height/depth (voxels). Example for a 256x128x127 volume (hex values): 01 00 00 80 00 7F Volume data format: 8 bit per voxel Data order: starting from top-left-front, going right first, then down, then back. This format does not support time dependent data, and it only supports 8 bit per voxel.

• .xvf: Short for 'extended volume data'. This format supports time dependent volume data and between 8 and 32 bits per voxel.

• .dat: Raw volume data without any header. The data can have 1,2,3, or 4 byte per voxel. The program tries to find the volume dimensions automatically, but you can help by passing them in the file name, e.g. "cthead256x256x64.dat" for a 256 x 256 x 64 voxels data set. Data order: starting from top-left-front, going right first, then down, then back. All bytes of each voxel must be stored consecutively, starting with the most significant byte or in RGBA order, depending on the data type.

• .ppm,.pgm: Portable Pixmap/Graymap files (binary version only). If this format is selected, the volume slices are written to disk as a number of 2D image files. The files will be numbered automatically. The volume data format decides about the use of PPM or PGM files. For scalar volume data the file format is PGM. PPM files are generated for color volume data.

These file types can be read by the module ReadVolume.

In the module parameters window, the FileName entry expects the destination file name. If OverwriteExisting is checked, the destination file will be overwritten, if it previously existed. The file type and data format can be selected with the respective choice menus. MinimumValue und MaximumValue allow to constrain the stored data range. All values that are smaller or equal to MinimumValue will become zero, values greater or equal to MaximumValue will become 255 or 65535, depending on the data format (8 or 16 bit per voxel). The remaining values are distributed linearly inbetween.

If packed RGBA or vector data is received on data port for channel 0, the other data channels are ignored.

WriteVolume is available for COVISE version snap-2002-07 and higher.

Parameters

Name	Type	Description
FileName	Browser	Volume file or first slice of sequence
OverwriteExisting	Boolean	Overwrite existing files?
FileType	Choice	File type of volume or slice files
DataFormat	Choice	Volume data format
MinimumValue	Scalar	Minimum scalar input value
MaximumValue	Scalar	Maximum scalar input value

Input Ports

Name	Type(s)	Description
grid	UniformGrid	Grid for volume data
channel0	Float Vec3 RGBA_Data	Scalar/vector volume data
channel1	Float	Scalar volume data channel 1
channel2	Float	Scalar volume data channel 2
channel3	Float	Scalar volume data channel 3
channel4	Float	Scalar volume data channel 4
channel5	Float	Scalar volume data channel 5
channel6	Float	Scalar volume data channel 6
channel7	Float	Scalar volume data channel 7

Examples

The above figure shows an example COVISE network to write volume data from GenDat.