The Raw File Read can be used
to read raw 2D or 3D data defined on a regular rectilinear grid. The data
can be in a single image file or a volume can be defined with multiple
image files. Although this is technically a reader and should therefore
be handle by Open Data, many parameters other than the file name are necessary
for reading raw data. Grouping this reader with the other source object
allows for a property sheet on which parameters can be specified. A file
prefix and pattern are used to determine the names of the files in the
series. The origin, extent, and spacing of the data must be specified
along with the number of components. If the image file is bigger than
expected from the extent and number of components, the extra bytes will
be considered a header at the beginning of the file and will be skipped.
If a 2D image is specified using the extent,
then the image will be mapped onto a plane and displayed. If a 3D image
is specified, the bounding box of this volume will be displayed. The image
plane or volume can be translated,
rotated, and scaled using the Actor control area of the Display tab for
this source, and it can be interactively positioned using the Move operation
of the camera. The
object created by this source is a vtkImageReader
object, and the output of this reader is vtkImageData.
. An example of a 2D image read using this raw file reader is given above.
The Raw File Reader has the following parameters:
File
Prefix: Type the path and base file name of the file(s) you wish
to read. You can also use the Browse button to locate a file. Be sure
to remove any extension that will be added by the file prefix. For example,
if you have a set of files image.1, image.2, image.3, etc located in /home/data,
the File Prefix would be /home/data/image and the pattern would supply
the .1, .2, .3, etc.
File
Pattern: This is the pattern to use when creating the file names.
By default this is set to %s.%d indicating that a "." and a
number will be appended to the file name given by the File Prefix. The
number will range across the Z extent of the data. If you specify the
exact file name for a 2D data file in the File Prefix, you can change
the File Pattern to %s to read that single file.
Data
Type: The Data Type pulldown allows you to select from the following
supported data types: char, unsigned char, short, unsigned short, int,
unsigned int, long, unsigned long, float, and double. This must be specified
accurately for the read to succeed.
Byte
Order: The byte ordering my be Little Endian or Big Endian. If
this is specified incorrectly, the will likely appear quite "noisy".
Origin:
The coordinate location of the origin of the image or volume can by specified
here. The default value is (0,0,0) and it is fine to leave this default
if you do not know the origin of your data.
Spacing:
The spacing values indicate the world coordinate distance between sample
points in the X, Y, and Z directions. The default values are all 1. If
you do not specify the spacing correctly, the image you see may appear
stretched or shrunk along an axis direction.
Extent:
The six extent values indicate the minimum and maximum X index values,
the minimum and maximum Y index values, and the minimum and maximum Z
index values. If these values are X1, X2, Y1, Y2, Z1, Z2, then each image
file is considered to be (X2-X1+1) by (Y2-Y1+1) elements (with X changing
fastest) and there are (Z2-Z1+1) images with the %d value in the file
pattern ranging from Z1 to Z2 (inclusive). The extent must be correctly
specified for the read succeed, except that the Z extent can be reduced.
For example, if you have a set of 100 images with names image.1, image.2,
image.3, etc. you can specify a Z extent of 50, 50 to read in only the
50th image in the series.
Num
Components: This entry box indicates the number of components per
scalar value in the raw data. By default this value is 1. If you are loading
I (intensity) data this value is 1, if you are loading IA (intensity alpha)
data the number of components is 2. RGB data has 3 components, and if
you are loading RGBA data this value would be 4.
The Raw File Read can be used
to read raw 2D or 3D data defined on a regular rectilinear grid. The data
can be in a single image file or a volume can be defined with multiple
image files. Although this is technically a reader and should therefore
be handle by Open Data, many parameters other than the file name are necessary
for reading raw data. Grouping this reader with the other source object
allows for a property sheet on which parameters can be specified. A file
prefix and pattern are used to determine the names of the files in the
series. The origin, extent, and spacing of the data must be specified
along with the number of components. If the image file is bigger than
expected from the extent and number of components, the extra bytes will
be considered a header at the beginning of the file and will be skipped.