Open Inventor Release 2023.2.2
 
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SoOrthoSlice Class Reference

VolumeViz Ortho slice shape node. More...

#include <VolumeViz/nodes/SoOrthoSlice.h>

+ Inheritance diagram for SoOrthoSlice:

Public Types

enum  Axis {
  X ,
  Y ,
  Z
}
 Slice Axis (see discussion of medical data axes in the class description) More...
 
enum  ClippingSide {
  FRONT ,
  BACK
}
 Clipping Side mode. More...
 
- Public Types inherited from SoSlice
enum  AlphaUse {
  ALPHA_AS_IS ,
  ALPHA_OPAQUE ,
  ALPHA_BINARY
}
 Alpha component usage mode Used in the alphaUse field. More...
 
- Public Types inherited from SoVolumeShape
enum  Interpolation {
  NEAREST ,
  LINEAR ,
  TRILINEAR ,
  MULTISAMPLE_12 ,
  CUBIC
}
 Interpolation mode. More...
 
enum  Composition {
  MAX_INTENSITY = 0 ,
  MIN_INTENSITY ,
  SUM_INTENSITY ,
  ALPHA_BLENDING ,
  COMPOSITION_LAST
}
 Composition mode. More...
 
- Public Types inherited from SoShape
enum  ShapeType {
  POINTS ,
  LINES ,
  POLYGONS ,
  TEXT
}
 Basic type for antialiased rendering for this shape (Do not consider the SoDrawStyle property currently in the state). More...
 

Public Member Functions

virtual SoType getTypeId () const
 Returns the type identifier for this specific instance.
 
 SoOrthoSlice ()
 Constructor.
 
virtual SbBool affectsState () const
 Overrides default method on SoShape.
 
virtual void setRenderProgress (SoProgressIndicator *ps) override
 Set an application defined SoProgressIndicator object which will raise an event before and after the rendering task, before and after each subtask (in this case: Texture creation and Geometry creation) and after each step in the subtasks which represents in most cases individual tiles of data.
 
- Public Member Functions inherited from SoShape
ShapeType getShapeType ()
 Gets the current shape Full Scene Antialiasing type.
 
- Public Member Functions inherited from SoNode
virtual void setOverride (const SbBool state)
 Turns the override flag on or off.
 
virtual SbBool isOverride () const
 Returns the state of the override flag.
 
virtual SoNodecopy (SbBool copyConnections=FALSE) const
 Creates and returns an exact copy of the node.
 
virtual void touch ()
 Marks an instance as modified, simulating a change to it.
 
- Public Member Functions inherited from SoFieldContainer
void setToDefaults ()
 Sets all fields in this object to their default values.
 
SbBool hasDefaultValues () const
 Returns TRUE if all of the object's fields have their default values.
 
SbBool fieldsAreEqual (const SoFieldContainer *fc) const
 Returns TRUE if this object's fields are exactly equal to fc's fields.
 
void copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE)
 Copies the contents of fc's fields into this object's fields.
 
SoNONUNICODE SbBool set (const char *fieldDataString)
 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.
 
SbBool set (const SbString &fieldDataString)
 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.
 
void get (SbString &fieldDataString)
 Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.
 
virtual int getFields (SoFieldList &list) const
 Appends references to all of this object's fields to resultList, and returns the number of fields appended.
 
virtual int getAllFields (SoFieldList &list) const
 Returns a list of fields, including the eventIn's and eventOut's.
 
virtual SoFieldgetField (const SbName &fieldName) const
 Returns a the field of this object whose name is fieldName.
 
virtual SoFieldgetEventIn (const SbName &fieldName) const
 Returns a the eventIn with the given name.
 
virtual SoFieldgetEventOut (const SbName &fieldName) const
 Returns the eventOut with the given name.
 
SbBool getFieldName (const SoField *field, SbName &fieldName) const
 Returns the name of the given field in the fieldName argument.
 
SbBool enableNotify (SbBool flag)
 Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE).
 
SbBool isNotifyEnabled () const
 Notification is the process of telling interested objects that this object has changed.
 
virtual void setUserData (void *data)
 Sets application data.
 
void * getUserData (void) const
 Gets user application data.
 
- Public Member Functions inherited from SoBase
virtual SbName getName () const
 Returns the name of an instance.
 
virtual void setName (const SbName &name)
 Sets the name of an instance.
 
void setSynchronizable (const bool b)
 Sets this to be a ScaleViz synchronizable object.
 
bool isSynchronizable () const
 Gets the ScaleViz synchronizable state of this object.
 
- Public Member Functions inherited from SoRefCounter
void ref () const
 Adds a reference to an instance.
 
void unref () const
 Removes a reference from an instance.
 
void unrefNoDelete () const
 unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.
 
int getRefCount () const
 Returns current reference count.
 
void lock () const
 lock this instance.
 
void unlock () const
 unlock this instance.
 
- Public Member Functions inherited from SoTypedObject
SbBool isOfType (const SoType &type) const
 Returns TRUE if this object is of the type specified in type or is derived from that type.
 
template<typename TypedObjectClass >
SbBool isOfType () const
 Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class.
 

Static Public Member Functions

static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoSlice
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoVolumeShape
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoLdmShape
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoShape
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
static SbBool isPrimitiveRestartAvailable (SoState *state=NULL)
 Returns TRUE if the primitive restart feature is available.
 
- Static Public Member Functions inherited from SoNode
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
static SoNodegetByName (const SbName &name)
 A node's name can be set using SoBase::setName().
 
static int getByName (const SbName &name, SoNodeList &list)
 A node's name can be set using SoBase::setName().
 
- Static Public Member Functions inherited from SoFieldContainer
static SoType getClassTypeId ()
 Returns the type of this class.
 
- Static Public Member Functions inherited from SoBase
static SoType getClassTypeId ()
 Returns type identifier for this class.
 
- Static Public Member Functions inherited from SoTypedObject
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 

Public Attributes

SoSFInt32 dataSetId
 Specifies the SoVolumeData node to use.
 
SoSFUInt32 sliceNumber
 Slice number.
 
SoSFEnum axis
 Slice axis (X, Y, or Z).
 
SoSFEnum clippingSide
 Specifies the clipping side.
 
SoSFBool clipping
 Activate/deactivate a clipping plane on a per-slice basis.
 
SoSFBool enableBorder
 Enables drawing the border.
 
SoSFColor borderColor
 Border color.
 
SoSFFloat borderWidth
 Border width in pixels.
 
SoSFBool enableImage
 Enables drawing the slice image.
 
- Public Attributes inherited from SoSlice
SoSFBool enableBumpMapping
 Specifies if a bump mapping effect will be applied to the slice.
 
SoSFFloat bumpScale
 Specifies the intensity of the bump mapping effect.
 
SoSFNode alternateRep
 This field optionally holds a subgraph containing only core Open Inventor nodes that can be used for rendering when VolumeViz is not available.
 
SoSFEnum alphaUse
 Specifies how to use the alpha component of each voxel's RGBA value.
 
SoSFBool useRGBA
 Specifies whether to create RGBA textures.
 
SoSFBool largeSliceSupport
 Activate/deactivate direct loading of full resolution slice data.
 
- Public Attributes inherited from SoVolumeShape
SoSFEnum interpolation
 Interpolation mode.
 
SoDEPRECATED SoSFEnum composition
 Specifies color composition mode.
 
- Public Attributes inherited from SoShape
SoSFBool boundingBoxIgnoring
 Whether to ignore this node during bounding box traversal.
 

Detailed Description

VolumeViz Ortho slice shape node.

This node defines an ortho (axis aligned) slice along the X, Y, or Z axis of the volume data defined by an SoVolumeData node. The slice orientation and position are defined by the axis and sliceNumber fields.

The SoVolumeData node can be specified with dataSetId. When this field is set to 0, the last SoVolumeData node on state is used.

For a non-RGBA (scalar valued) volume, each voxel's RGBA value is determined by the current SoDataRange and SoTransferFunction. The current diffuse color and transparency (set, for example, with an SoMaterial node) modifies the appearance of the slice. This means that, for example, the current transparency can be used as an global alpha value to modulate the overall opacity of the slice.
For an RGBA volume each voxel's RGBA value comes directly from the volume data.

The interpolation field controls how the texture is interpolated.

The alphaUse field (SoSlice) controls how the voxel's alpha component is used when drawing the slice.

Optionally a bump mapping effect may be applied. Normal vectors are automatically computed from the data value gradient. The enableBumpMapping and bumpScale fields (SoSlice) control whether bump mapping is active and the intensity of the effect.

Notes:

  • Drawing position:
    The SoOrthoSlice geometry passes through the center of the voxels in the specified slice. So, for example, an ortho slice with sliceNumber = 0 will be drawn one-half voxel size (on the slice axis) in from the bounding box of the volume. This is slightly different from SoVolumeSkin. A volume skin is approximately the same as six ortho slices, but each face of the skin is drawn at the outer edge of the voxel.
  • Transformation matrices:
    The volume size and orientation (like geometry) can be modified by transformation nodes in the scene graph and this in turn modifies the appearance of volume visualization nodes. However, the same transformation must be applied to the volume data node and all volume visualization nodes associated with that volume. So effectively any transformation nodes that affect the volume must be placed before the volume data node.
  • Picking:
    The entire slice is pickable, even where it is transparent as a result of the current transfer function. The SoOrthoSliceDetail class allows you to get the voxel position and value after picking.
  • Dragging:
    It is possible to interactively translate and rotate slices using an Open Inventor dragger, e.g. SoTranslate1Dragger. However the dragger's position in XYZ space must be converted to a slice number. For a dragger that is specific to ortho slices, see the class SoOrthoSliceDragger.
  • Interpolation:
    Interpolation is specified using the interpolation field. The default (LINEAR) does bi-linear interpolation between voxel values. The NEAREST value can be used to display individual voxels. For best image quality we recommend using the MULTISAMPLE_12 value.
  • Data range:
    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 SoDataRange node to specify the actual (or desired) range of data values to be mapped. Also use an SoDataRange node to implement brightness/contrast control like the Window/Level setting commonly used with medical images.
  • Clipping:
    Volume primitives can be clipped using a region of interest (SoROI), geometry (SoVolumeClippingGroup) and/or height fields (SoUniformGridClipping). They are also clipped by OpenGL clipping planes (SoClipPlane), but we recommend using the VolumeViz clipping nodes instead.
    Optionally, this node also defines a clipping plane. Similar to SoClipPlane, this clipping plane affects all subsequent geometry, including SoVolumeRender, but does not of course affect the ortho slice itself. The clipping and clippingSide fields control whether clipping is active and which half-space is clipped. Clipping side FRONT means that the clip plane (removes) clips away geometry in the positive direction on the slice axis.
  • Border:
    Border can be enabled with the enableBorder field, which allows to draw a border around the slice following volume boundary. However, the border is invisible when an SoROI (or SoROIManip) is used in the scene.
  • Material:
    The color of each voxel is modulated by the current diffuse color in the traversal state. The default diffuse color is 0.8,0.8,0.8. This results in full intensity values in the color map being displayed as 80% intensity. Therefore we recommend adding an SoMaterial node before the slice and setting its diffuseColor field to full white (1,1,1).
  • Transparency:

    • Typically the color map (SoTransferFunction) used for volume rendering (SoVolumeRender) assigns transparency (alpha < 1) to some voxel values. You can use the same color map for slice rendering, but note that the default value of the alphaUse field (since Open Inventor 10.0) is ALPHA_OPAQUE, meaning that alpha values in the color map are ignored. However, it does not affect the transparency assigned by an SoMaterial node.

    • If you want to adjust the overall transparency of the slice, set the alphaUse field to ALPHA_AS_IS, add an SoMaterial node and set its transparency field. Effectively a scale factor 1-transparency is applied to each voxel's alpha value.

    • Intersecting transparent slices cannot be rendered correctly by the basic blending transparency algorithms. To render this case correctly, set the transparency algorithm to SORTED_PIXEL using the viewer class or SoGLRenderAction.
  • Voxel edges:
    The edges of the voxels can also be rendered. See options in the SoVolumeRenderingQuality node.
  • Custom shaders:
    The current SoVolumeShader node, if any, allows custom shaders to be defined for special computation or rendering effects, including blending multiple volumes.
  • Composition with Multiple Data:
    It is possible to compose datasets that have different dimensions, tile sizes and transformations.
    In order to help fetch the correct data values in custom shaders, texture coordinates conversion functions are provided in the VolumeViz/vvizStructure.h shader include.
    For instance,
    vec3 VVizTextureToTextureVec(in VVizDataSetId datasetSrc, in VVizDataSetId datasetDst, in vec3 texCoord);
    vec3 VVizTextureToTextureVec(in VVizDataSetId datasetSrc, in VVizDataSetId datasetDst, in vec3 texCoord)
    Converts the input vector from the texture space of one dataset to the texture space of another datas...
    can be used to convert texture coordinates related to one dataset to texture coordinates related to another dataset.
    The conversion is based solely on the transformations applied to each dataset, which are defined by their model matrix and their extent.
    Please note that the model matrix of a dataset is defined by to the SoTransformation nodes that are placed before the SoDataSet node in the order of the traversal.
  • Large Slice mode:
    When the "large slice" mode is enabled (see SoSlice::largeSliceSupport), if all the required full resolution tiles have already been loaded, then the slice data is taken from LDM system memory cache as usual. But if some required tiles are not currently in memory, the required slice data will be loaded directly from the volume reader without loading the complete tiles. This reduces disk I/O and reduces the amount of system memory required to display the slice at full resolution, so larger (or more) slices can be displayed. The required tiles are then scheduled to be loaded asynchronously in case adjacent slices are displayed later. For example, loading a 1024x1024 SoOrthoSlice from an 8-bit dataset with 128x128x128 tiles would normally require loading 1024x1024x128 bytes of data (as complete tiles). With largeSliceSupport enabled, only 1024x1024 bytes (maximum) of data need to be loaded (in the worst case where no high resolution data is currently in memory).
  • Performance:
    • 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 (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 SoVolumeRender but somewhat inefficient for slice rendering because complete tiles must be loaded even though the slice only uses a 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 SoConverter and the "-t" option). For other data formats the tile size can be specified using the SoVolumeData node's ldmResourceParameters field, but only after setting the filename field or calling the setReader() method.

    • LDM_USE_IN_MEM_COMPRESSION
      VolumeViz always manages data as "tiles", regardless of the data format. In many cases VolumeViz must create (or uncompress) the tiles at run time. These cases include in-memory volumes, any volume reader that does not implement the readTile() method (this includes all built-in formats except LDM, e.g. DICOM, SEGY, ...) and compressed LDM format files. If this variable is true (the default), VolumeViz only keeps a small cache of created/uncompressed tiles in CPU memory. If a tile's data is needed and that tile is not in the cache, the tile must be recreated. This overhead can be significant, especially for operations that require recreating all the data textures on the GPU, for example changing the data range (SoDataRange). We recommend setting this variable to false (see SoPreferences) unless saving CPU memory is critical.

    • Compressed textures
      For performance reasons, SoOrthoSlice accumulates small textures into a bigger one. When using compressed RGBA textures (via SoDataSet's field useCompressedTexture), this optimization cannot be done. If you want to favor performance rather than memory usage, you should disable compression (enabled by default if supported by the graphic card)
  • Medical data axes:
    The three standard axes (or viewing planes) are Axial, Coronal and Sagittal. How these axes correspond to the IJK axes in voxel space and the XYZ axes in 3D space depends on the data set. However DICOM volumes typically have LPS (Left, Posterior, Superior) orientation and in this case:
    • Axial is the Z axis
      i.e., toward the head (Superior) is the K / +Z / Axial axis.

    • Coronal is the Y axis
      i.e., toward the back of the body (Posterior) is the J / +Y / Coronal axis.

    • Sagittal is the X axis
      i.e., toward the left side of the body (Left) is the I / +X / Sagittal axis.

EXAMPLE

FILE FORMAT/DEFAULT

    OrthoSlice {
    dataSetId 0
    sliceNumber 0
    axis Z
    interpolation LINEAR
    alphaUse ALPHA_BINARY
    useRGBA FALSE
    clipping FALSE
    clippingSide BACK
    alternateRep NULL
    enableBumpMapping FALSE
    bumpScale 1.0
    enableBorder FALSE
    borderColor 0.84 0.43 0.02
    borderWidth 2.0
    enableImage TRUE
    }

ACTION BEHAVIOR

SEE ALSO

SoDataRange, SoObliqueSlice, SoOrthoSliceDragger, SoROI, SoSlice, SoTransferFunction, SoVolumeData

Definition at line 450 of file SoOrthoSlice.h.

Member Enumeration Documentation

◆ Axis

Slice Axis (see discussion of medical data axes in the class description)

Enumerator

X Axis.

Y Axis.

Z Axis (Default)

Definition at line 476 of file SoOrthoSlice.h.

◆ ClippingSide

Clipping Side mode.

Enumerator
FRONT 

Front.

BACK 

Back (Default)

Definition at line 492 of file SoOrthoSlice.h.

Constructor & Destructor Documentation

◆ SoOrthoSlice()

SoOrthoSlice::SoOrthoSlice ( )

Constructor.

Member Function Documentation

◆ affectsState()

virtual SbBool SoOrthoSlice::affectsState ( ) const
virtual

Overrides default method on SoShape.

It must return TRUE if clip plane is activated. Used internally, especially for path traversal. Probably no reason for applications to ever call it.

Reimplemented from SoShape.

◆ getClassTypeId()

static SoType SoOrthoSlice::getClassTypeId ( )
static

Returns the type identifier for this class.


◆ getTypeId()

virtual SoType SoOrthoSlice::getTypeId ( ) const
virtual

Returns the type identifier for this specific instance.

Reimplemented from SoSlice.

Reimplemented in OrthoSliceBorder.

◆ setRenderProgress()

virtual void SoOrthoSlice::setRenderProgress ( SoProgressIndicator ps)
overridevirtual

Set an application defined SoProgressIndicator object which will raise an event before and after the rendering task, before and after each subtask (in this case: Texture creation and Geometry creation) and after each step in the subtasks which represents in most cases individual tiles of data.

- SoProgressIndicator::onBeginTask / SoProgressIndicator::onEndTask will be raised only one time per frame : "Rendering".

Track loading progression with SoProgressIndicator::onEndStep event of SubTask "Loading Texture":

  • NumSteps represents here the number of tiles to load to reach the "stable rendering state".
  • NumStepsDone represents here the number of tiles currently loaded since the last NumSteps reset.
  • The two numbers are reset when the viewer is moving the camera.

The example VolRend (examples/source/VolumeViz/VolRend) implements a loading progress bar in class EventRaisedProgressBar.

Limitations :

If set to NULL no events will be raised. Default is NULL.

Since Open Inventor 2023.2

Reimplemented from SoVolumeShape.

Member Data Documentation

◆ axis

SoSFEnum SoOrthoSlice::axis

Slice axis (X, Y, or Z).

Use enum Axis. Default is Z.

Definition at line 489 of file SoOrthoSlice.h.

◆ borderColor

SoSFColor SoOrthoSlice::borderColor

Border color.

Default is [0.84, 0.43, 0.02] (orange luminance 55%).

NOTE: field available since Open Inventor 10.10

Definition at line 551 of file SoOrthoSlice.h.

◆ borderWidth

SoSFFloat SoOrthoSlice::borderWidth

Border width in pixels.

Default is 2. For more information about borderWidth units: see SoDrawStyle::lineWidth

NOTE: field available since Open Inventor 10.10

Definition at line 559 of file SoOrthoSlice.h.

◆ clipping

SoSFBool SoOrthoSlice::clipping

Activate/deactivate a clipping plane on a per-slice basis.

Optionally, this node also defines a clipping plane. Similar to SoClipPlane, this clipping plane affects all subsequent geometry, including SoVolumeRender, but does not of course affect the ortho slice itself. The clippingSide field controls which half-space is clipped.

Definition at line 537 of file SoOrthoSlice.h.

◆ clippingSide

SoSFEnum SoOrthoSlice::clippingSide

Specifies the clipping side.

Use enum ClippingSide. Default is BACK. Clipping side FRONT means that the clip plane (removes) clips away geometry in the positive direction on the slice axis. BACK means that the clip plane clips away geometry in the negative direction on the slice axis.

These figures show an ortho slice clipping a data volume.

Right:
  - #alphaUse = ALPHA_BINARY <BR>
  - #interpolation = LINEAR

Bottom left:
  - #alphaUse = ALPHA_OPAQUE <BR>
  - #interpolation = LINEAR

Bottom right:
  - #alphaUse = ALPHA_BINARY <BR>
  - #interpolation = NEAREST

Definition at line 528 of file SoOrthoSlice.h.

◆ dataSetId

SoSFInt32 SoOrthoSlice::dataSetId

Specifies the SoVolumeData node to use.

This is useful when datasets of different dimensions are present in the scene graph. Please see SoMultiDataSeparator for more details.

When set to 0, the last SoVolumeData node on state is used. Default is 0.

NOTE: field available since Open Inventor 10.11.0

Definition at line 468 of file SoOrthoSlice.h.

◆ enableBorder

SoSFBool SoOrthoSlice::enableBorder

Enables drawing the border.

Default is false.

NOTE: field available since Open Inventor 10.10

Definition at line 544 of file SoOrthoSlice.h.

◆ enableImage

SoSFBool SoOrthoSlice::enableImage

Enables drawing the slice image.

Default is true. Note that setting this field to false makes the slice image invisible, but the slice is still detectable by picking if the border is enabled.

Example of a typical use case : The folling code shows how to use a boolean engine to disable the image rendering while dragging.

engine->a.connectFrom(&dragger->isActive);
orthoslice->enableImage.connectFrom(&engine->inverse);
Performs Boolean operations.
Smart pointer for any class inheriting SoRefCounter.
Definition SoRef.h:90

Another typical usecase is if you want to display the slice image in a 2D view and also show only the slice position in a 3D view (without the slice image).

NOTE: field available since Open Inventor 10.10

Definition at line 594 of file SoOrthoSlice.h.

◆ sliceNumber

SoSFUInt32 SoOrthoSlice::sliceNumber

Slice number.

Definition at line 473 of file SoOrthoSlice.h.


The documentation for this class was generated from the following file: