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SoDataRange Class

Range of data values to be mapped to the color map.

Inheritance Hierarchy

Namespace: OIV.LDM.Nodes
Assembly: OIV.LDM (in OIV.LDM.dll) Version: 2024.1.2.0 (2024.1.2)
Syntax
public class SoDataRange : SoNode

The SoDataRange type exposes the following members.

Constructors
  NameDescription
Public methodSoDataRange

Constructor.

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Methods
  NameDescription
Public methodAffectsState

Returns true if a node has an effect on the state during traversal.

(Inherited from SoNode.)
Public methodCallback
Public methodCopy
Calls Copy(false).
(Inherited from SoNode.)
Public methodCopy(Boolean)

Creates and returns an exact copy of the node.

(Inherited from SoNode.)
Public methodCopyFieldValues(SoFieldContainer)
Calls CopyFieldValues(fc, false).
(Inherited from SoFieldContainer.)
Public methodCopyFieldValues(SoFieldContainer, Boolean)

Copies the contents of fc's fields into this object's fields.

(Inherited from SoFieldContainer.)
Public methodDispose
Releases all resources used by SoDisposable.
(Inherited from SoDisposable.)
Public methodDistribute
(Inherited from SoNode.)
Public methodDoAction
Public methodEnableNotify

Notification at this Field Container is enabled (if flag == true) or disabled (if flag == false).

(Inherited from SoFieldContainer.)
Public methodEquals
Determines whether the specified Object is equal to the current Object.
(Inherited from Object.)
Public methodFieldsAreEqual

Returns true if this object's fields are exactly equal to fc's fields.

(Inherited from SoFieldContainer.)
Public methodGet

Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.

(Inherited from SoFieldContainer.)
Public methodGetAllFields

Returns a list of fields, including the eventIn's and eventOut's.

(Inherited from SoFieldContainer.)
Public methodGetAlternateRep

This method is called by actions to allow the node to provide an "alternate representation" when appropriate (typically depending on the action type).

(Inherited from SoNode.)
Public methodGetBoundingBox
Public methodGetEventIn

Returns a the eventIn with the given name.

(Inherited from SoFieldContainer.)
Public methodGetEventOut

Returns the eventOut with the given name.

(Inherited from SoFieldContainer.)
Public methodGetField

Returns a the field of this object whose name is fieldName.

(Inherited from SoFieldContainer.)
Public methodGetFieldName

Returns the name of the given field in the fieldName argument.

(Inherited from SoFieldContainer.)
Public methodGetFields

Appends references to all of this object's fields to resultList, and returns the number of fields appended.

(Inherited from SoFieldContainer.)
Public methodGetHashCode
Overrides GetHashCode().
(Inherited from SoNetBase.)
Public methodGetMatrix
(Inherited from SoNode.)
Public methodGetName

Returns the name of an instance.

(Inherited from SoBase.)
Public methodGetPrimitiveCount
(Inherited from SoNode.)
Public methodGetRenderEngineMode

Returns the supported Render engine mode.

(Inherited from SoNode.)
Public methodGetRenderUnitID
(Inherited from SoNode.)
Public methodGetStringName (Inherited from SoBase.)
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodGLRender
Public methodGLRenderBelowPath
(Inherited from SoNode.)
Public methodGLRenderInPath
(Inherited from SoNode.)
Public methodGLRenderOffPath
(Inherited from SoNode.)
Public methodGrabEventsCleanup
(Inherited from SoNode.)
Public methodGrabEventsSetup
(Inherited from SoNode.)
Public methodHandleEvent
(Inherited from SoNode.)
Public methodHasDefaultValues

Returns true if all of the object's fields have their default values.

(Inherited from SoFieldContainer.)
Public methodIsBoundingBoxIgnoring

This method is used by getBoundingBox action traversal to know if the current node must be traversed or not, ie the bounding should be ignored.

(Inherited from SoNode.)
Public methodIsNotifyEnabled

Notification is the process of telling interested objects that this object has changed.

(Inherited from SoFieldContainer.)
Public methodIsOverride

Returns the state of the override flag.

(Inherited from SoNode.)
Public methodIsSynchronizable

Gets the ScaleViz synchronizable state of this object.

(Inherited from SoBase.)
Public methodPick
Public methodRayPick
(Inherited from SoNode.)
Public methodSearch
(Inherited from SoNode.)
Public methodSet

Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.

(Inherited from SoFieldContainer.)
Public methodSetName (Inherited from SoBase.)
Public methodSetOverride

Turns the override flag on or off.

(Inherited from SoNode.)
Public methodSetSynchronizable

Sets this to be a ScaleViz synchronizable object.

(Inherited from SoBase.)
Public methodSetToDefaults

Sets all fields in this object to their default values.

(Inherited from SoFieldContainer.)
Public methodToString
Converts this SoBase structure to a human readable string.
(Inherited from SoBase.)
Public methodTouch

Marks an instance as modified, simulating a change to it.

(Inherited from SoNode.)
Public methodWrite
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Properties
  NameDescription
Public propertydataRangeId

This field allows the use of multiple data ranges for the same shape.

Public propertyIsDisposable
ISafeDisposable interface implementation.
(Inherited from SoDisposable.)
Public propertymapOnFullColorRange

Specifies how to map data values that are outside of the data range.

Public propertymax

Maximum data value of the data range.

Public propertymin

Minimum data value of the data range.

Public propertyUserData
Gets or sets the user data to be contained by the field container.
(Inherited from SoFieldContainer.)
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Remarks

This node allows you to specify the range of scalar data values in a data set (OIV.LDM.Nodes.SoDataSet or OIV.VolumeViz.Nodes.SoVolumeData) that will be mapped into the color map (OIV.LDM.Nodes.SoTransferFunction). When the volume data type is larger than the data type on the GPU, for example float data scaled to byte data, it also specifies the range of scalar data values that will be scaled to fit in the GPU data type.

By default VolumeViz maps the entire range of the voxel's data type (e.g. 0..65535 for unsigned short) into the colormap. This is often correct for byte (8 bit) voxels, but seldom correct for 16 bit voxels and never correct for floating point voxels. Use an OIV.LDM.Nodes.SoDataRange node to specify the actual (or desired) range of data values to be mapped. For example, a typical initial data range for DICOM data calibrated in Hounsfield units might be -1000 to 3000.

Data characteristics:

  • The voxel value data type can be queried using the OIV.LDM.Nodes.SoDataSet method getDataType().

  • The number of bytes in a voxel value can be queried using the OIV.LDM.Nodes.SoDataSet method getDataSize().

  • The actual min and max values for the data set can be queried using the OIV.LDM.Nodes.SoDataSet method getMinMax(). Note that this method might force VolumeViz to load the entire data set if the volume reader for that format does not implement the getMinMax query. Normally for an LDM format data set, the min and max values are stored in the LDM header. For a non-LDM data set, if a filename and/or reader have been specified and the data set has not yet been loaded, VolumeViz will load the entire data set to compute the min and max values. For a large data set this may take a long time.

  • DICOM: The Window Center (0028,1050) and Window Width (0028,1051) values (if present in the data set) can be queried by using an OIV.VolumeViz.Readers.SoVRDicomData object obtained from the OIV.VolumeViz.Readers.SoVRDicomFileReader or by using the MedicalHelper class. You can also use the MedicalHelper method dicomAdjustDataRange.

When using multiple volumes (see OIV.LDM.Nodes.SoMultiDataSeparator), a single OIV.LDM.Nodes.SoDataRange node can be used to specify the data range for all volumes or each volume can have its own independent data range. In the second case, create one OIV.LDM.Nodes.SoDataRange node for each volume and set the OIV.LDM.Nodes.SoDataRange.dataRangeId equal to the OIV.LDM.Nodes.SoDataSet.dataSetId of the corresponding volume.

Note that the meaning of the min and max fields in OIV.LDM.Nodes.SoDataRange is quite different than the meaning of the minValue and maxValue fields in OIV.LDM.Nodes.SoTransferFunction. The fields in OIV.LDM.Nodes.SoDataRange specify the range of voxel values that will be mapped into the full color map. The fields in OIV.LDM.Nodes.SoTransferFunction specify the range of indices in the color map that will actually be used to store the color map. The visual effect changing these fields can be quite similar, but there are trade-offs to be aware of. Changing the OIV.LDM.Nodes.SoTransferFunction fields is generally much faster and can be a useful approximation of changing the data range, but the resolution of the color map (the ratio of data values to color map entries) is reduced.

NOTE: Setting the min value greater than or equal to the max value will cause this node to be ignored.

Brightness and contrast:

Often the distribution of voxel values within the actual data range is not uniform and more details can be seen by adjusting the OIV.LDM.Nodes.SoDataRange values to increase brightness and/or contrast. This is particularly true when using a gray scale color map (for example the predefined INTENSITY map in OIV.LDM.Nodes.SoTransferFunction ). In medical imaging this range setting is often specified by the window center and window width. The window center is the image intensity that will be displayed as a medium-gray and the window width is the range of data values between full black and full white. For example, if the data volume contains byte data with a native range of 0 to 255, the default data range (0 to 255) is effectively specifying a window center of 128 and width of 256. To increase contrast in the resulting image we might set a data range of 20 to 110, which makes the window center and width 65 and 90 respectively.

Performance:

For larger data types, changing the data range may require VolumeViz to recreate the data textures on the GPU. This is necessary to maximize use of the available bits of precision on the GPU. Since Open Inventor 9.6, recreating data textures should not be required for 8 bit data or for 16 bit data when the OIV.LDM.Nodes.SoDataSet.texturePrecision field is set to 16. Recreating data textures may be slow for larger volumes, even in the 512^3 range. There are several parameters that significantly affect this:

  • Tile size: For backward compatibility, the default tile size is still only 64. This is quite small for modern CPU/GPU hardware. The smaller the tile size, the larger the total number of tiles that must be managed by VolumeViz. This overhead can be significant, especially for operations that require reloading the data textures on the GPU, for example, changing the data range (OIV.LDM.Nodes.SoDataRange). For smaller volumes, like 512^3, it can be efficient to set the tile size large enough to contain the entire volume. For very large volumes, larger tile sizes are efficient for OIV.VolumeViz.Nodes.SoVolumeRender but somewhat inefficient for slice rendering because complete tiles must be loaded even though the slice only uses part of the data. Applications should experiment. For volumes stored in LDM file format, the tile size must be specified when the volume is converted to LDM (see OIV.LDM.Converters.SoConverter and the "-t" option). For other data data formats the tile size should be specified after the OIV.VolumeViz.Nodes.SoVolumeData node is created, using the ldmResourceParameters field, but before setting the filename field.

  • Tile cache policy: It specifies how the tiles are stored in CPU memory. The selected policy can significantly impact the data loading performance versus the CPU memory footprint. See OIV.LDM.Nodes.SoLDMResourceParameters.tileCachePolicy for detail.

  • OIV.LDM.Nodes.SoDataSet.texturePrecision When the data set's texturePrecision is at least equal to the numSignificantBits, then the data range scaling can be applied on the fly during rendering (i.e. on the GPU). This implies that data textures don't need to be regenerated when the data range changes and interactivity is much better.

  • SoVolumeRender.subDivideTiles This parameter doesn't actually resend data to the GPU but it does require updating the sub-tile min/max values, which can be quite costly. Setting subDivideTiles to false may increase DataRange performance (the default is false).

If the data set contains explicit RGBA values (OIV.VolumeViz.Nodes.SoVolumeData dataRGBA field is true), then OIV.LDM.Nodes.SoDataRange and OIV.LDM.Nodes.SoTransferFunction have no effect on rendering.

FILE FORMAT/DEFAULT

DataRange{
dataRangeId 1
min 0
max 0
mapOnFullColorRange true
}

ACTION BEHAVIOR

OIV.Inventor.Actions.SoCallbackAction, OIV.Inventor.Actions.SoGLRenderAction, OIV.Inventor.Actions.SoPickAction, OIV.Inventor.Actions.SoWriteAction, OIV.Inventor.Actions.SoGetBoundingBoxAction Sets a data range in the current traversal state.

See Also