Module category: IO

• ReadVolume
  • Parameters
  • Output Ports
  • Examples

ReadVolume

This module reads volume data files and provides the scalar volume data on a uniform grid.

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 read:

• .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.

• .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.

• .xvf: Short for 'extended volume data'. This format supports time dependent volume data.

• .tif, .tiff: 3D TIF File format.

DAT, RVF, and XVF files can be generated by the module WriteVolume.

The following 2D image file formats are supported to create volumes from sequences of slice images:

• .rgb: SGI RGB image file (8 bit grayscale only)
• .pgm: Portable Graymap file (binary version only)
• .ppm: Portable Pixmap file (binary version only)
• .dcm, .dcom: DICOM medical images
• .tif, .tiff: 2D TIF files (uncompressed only)

Please note that the reading algorithm is chosen according to the file name extension - rename your files accordingly.

For reading sequences of files you have to enter a printf(3) format string instead of the actual file name, the integer values from SequenceBegin to SequenceEnd-1 are used for generating the file names. E. g. if you want to read the files slice001.dcm, ..., slice123.dcm you would pass the format string slice%03d.dcm. Missing files in the sequence are skipped.

ReadVolume is available for COVISE version snap-2001-02 and higher.

Parameters

Name	Type	Description
FilePath	Browser	Volume file (or printf format string for sequence)
SequenceBegin	Scalar	First file number in sequence
SequenceEnd	Scalar	Last file number in sequence
CustomSize	Boolean	Off: use size values from volume file, on: use size values from below
VolumeWidth	Scalar	Volume width
VolumeHeight	Scalar	Volume height
VolumeDepth	Scalar	Volume depth
ReadRaw	Boolean	Off: read data according to file format guessed from extension, on: read raw data as specified below
NumVoxelX	Scalar	Number of voxels in x direction (width)
NumVoxelY	Scalar	Number of voxels in y direction (height)
NumVoxelZ	Scalar	Number of voxels in z direction (slices)
BytePerChannel	Scalar	Byte per channel
NumberOfChannels	Scalar	Number of channels
HeaderSize	Scalar	Offset of raw volume data from file beginning

Output Ports

Name	Type(s)	Description
grid	UniformGrid	Grid for volume data
channel0	Float	Scalar volume data channel 0
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 figure above shows a map for reading a 57 x 57 x 95 voxels air flow simulation data set.

The last figure is a snapshot of the renderer. It shows the visualization of the air flow simulation.

(Don't forget to hit "Apply" in the ColorMap Editor Panel, otherwise you will see nothing in the Renderer window)

The above data set (lambda.rvf) is courtesy of Ulrich Rist, IAG, University of Stuttgart.