Open Inventor Release 2023.2.2
 
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SoVolumeSkin Class Reference

VolumeViz Draws a data volume skin. More...

#include <VolumeViz/nodes/SoVolumeSkin.h>

+ Inheritance diagram for SoVolumeSkin:

Public Types

enum  FaceMode {
  FRONT ,
  BACK ,
  FRONT_AND_BACK
}
 Use this enum with the faceMode field. 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.
 
 SoVolumeSkin ()
 Constructor.
 
- Public Member Functions inherited from SoVolumeShape
virtual void setRenderProgress (SoProgressIndicator *ps)
 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
virtual SbBool affectsState () const
 Overrides default method on SoNode.
 
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.
 
SoSFEnum faceMode
 Display front (facing the camera) faces or back faces.
 
- 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.
 

Friends

class SoVolumeSkinLdm
 

Detailed Description

VolumeViz Draws a data volume skin.

This node draws the "skin" (outer faces) of the data volume defined by the current SoVolumeData node. This skin is a set of textured polygons similar to ortho slices.

The current 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) modify the appearance of the voxels. This means that, for example, the current transparency can be used as a global alpha value to modulate the overall opacity. For an RGBA volume each voxel's RGBA value comes directly from the volume data.

When using an opaque transfer function (no alpha values < 1), this node generates the same image as SoVolumeRender, but with much higher performance, because only slices are rendered. A common pattern is to put an SoVolumeRender node and an SoVolumeSkin node under an SoSwitch node. This makes it easy to switch between skin rendering and volume rendering.

The interpolation field controls how the texture is interpolated.

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

The entire skin is pickable, even where it is transparent as a result of the current transfer function. The SoVolumeSkinDetail class allows you to get the voxel position and value after picking.

Notes:

  • Drawing position:
    An SoVolumeSkin is approximately the same as six ortho slices, but not exactly. The difference is that each face of the skin is drawn at the outer edge of the voxel slice it intersects. So if there is no SoROI, or the ROI is identical to the volume dimensions, the volume skin faces will be drawn at the limits of the volume extent (bounding box). For SoOrthoSlice, the geometry passes through the center of the voxels in the specified slice. So 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.
  • 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 rendering nodes like SoVolumeSkin. However the same transformation must be applied to the volume data node and all volume rendering 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 skin is pickable, even where it is transparent as a result of the current transfer function. The SoVolumeSkinDetail class allows you to get the voxel position and value after picking.
  • 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.

    Note that, in general, clipping does not work well with SoVolumeSkin because the clipped portions of the skin are not "closed", allowing the user to see inside the skin. However the SoROI node's EXCLUSION_BOX mode does work well and can be used to exclude a sub-region from the skin, forming what is sometimes called a "chair cut".
  • Dragging:
    It is possible to interactively translate and resize a skin that is limited to a subset of the volume (sometimes called a "volume probe"). This is done using an Open Inventor dragger, e.g. SoTabBoxDragger, to adjust an SoROI node. This is such a common operation that Open Inventor provides the SoROIManip node.
  • 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 TRILINEAR or MULTISAMPLE_12 value.
  • 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 skin 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. If you want to use the same color map for skin rendering, but render the slice completely opaque, set the alphaUse field to ALPHA_OPAQUE. This overrides the alpha values in the color map (or an RGBA volume). However it does not affect transparency assigned using an SoMaterial node.
  • 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 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 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, SoVolumeSkin 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)

EXAMPLE

FILE FORMAT/DEFAULT

    VolumeSkin {
    dataSetId 0
    interpolation LINEAR
    alphaUse ALPHA_AS_IS
    useRGBA FALSE
    enableBumpMapping FALSE
    bumpScale 1.0
    faceMode FRONT
    }

ACTION BEHAVIOR

SEE ALSO

SoVolumeData, SoTransferFunction, SoROI, SoVolumeShader

Definition at line 411 of file SoVolumeSkin.h.

Member Enumeration Documentation

◆ FaceMode

Use this enum with the faceMode field.

Enumerator
FRONT 

Display only front faces.

BACK 

Display only back faces.

FRONT_AND_BACK 

Display front and back faces.

Definition at line 420 of file SoVolumeSkin.h.

Constructor & Destructor Documentation

◆ SoVolumeSkin()

SoVolumeSkin::SoVolumeSkin ( )

Constructor.

Member Function Documentation

◆ getClassTypeId()

static SoType SoVolumeSkin::getClassTypeId ( )
static

Returns the type identifier for this class.


◆ getTypeId()

virtual SoType SoVolumeSkin::getTypeId ( ) const
virtual

Returns the type identifier for this specific instance.

Reimplemented from SoSlice.

Friends And Related Symbol Documentation

◆ SoVolumeSkinLdm

friend class SoVolumeSkinLdm
friend

Definition at line 545 of file SoVolumeSkin.h.

Member Data Documentation

◆ dataSetId

SoSFInt32 SoVolumeSkin::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 446 of file SoVolumeSkin.h.

◆ faceMode

SoSFEnum SoVolumeSkin::faceMode

Display front (facing the camera) faces or back faces.

Use enum FaceMode. Default is FRONT. Displaying only front (or back) faces reduces the amount of data that must be loaded and reduces the rendering time.

NOTE: field available since Open Inventor 8.1

Definition at line 456 of file SoVolumeSkin.h.


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