SoVolumeDetail Class Reference

Base class for detail information about picking in a data volume. More...

#include <VolumeViz/details/SoVolumeDetail.h>

Inheritance diagram for SoVolumeDetail:

Public Member Functions
virtual SoType	getTypeId () const
	Returns the type identifier for this specific instance.
	SoVolumeDetail ()
	Constructor.
virtual	~SoVolumeDetail ()
	Destructor.
void	getProfileObjectPos (SbVec3f profile[2]) const
	Returns the profile position in object space (world coordinates).
int	getProfileDataPos (SbVec3i32 profile[2]) const
	Returns the number of values along the profile and the profile position in data space (voxel coordinates).
int64_t	getProfileValue (int index, SbVec3i32 &pos, SbVec3f *objPos=0, SbBool realValue=FALSE) const
	Returns the index'th value (as an integer) and its position in object and data space.
double	getProfileValueD (int index, SbVec3i32 &pos, SbVec3f *objPos, SbBool realValue=FALSE) const
	Returns the index'th value (as a double) and its position in object and data space.
virtual SbBool	getFirstNonTransparentValue (int64_t &value, SbVec3i32 &pos, SbVec3f *objPos=0, SbBool realValue=FALSE) const
	Retrieves the value and position of the first non-transparent voxel along the pick ray (if any).
virtual SbBool	getFirstNonTransparentValue (double &value, SbVec3i32 &pos, SbVec3f *objPos=0, SbBool realValue=FALSE) const
	Retrieves the value and position of the first non-transparent voxel along the pick ray (if any).
virtual SoDetail *	copy () const
	Returns an instance that is a copy of 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 SoDetail
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.

Detailed Description

Base class for detail information about picking in a data volume.

A successful pick operation returns an SoPickedPoint object. If the picked geometry is an SoVolumeSkin or SoVolumeRender, use the getDetail method and cast the result to the appropriate class (SoVolumeSkinDetail or SoVolumeRenderDetail) to get extra information about the location of the pick.

SoVolumeDetail returns information about the first (closest) non-transparent voxel along the pick ray and/or information about all the voxels intersected by the pick ray (called a profile). For the first non-transparent voxel (if any) on the pick ray, it returns XYZ position, IJK location, and data value. For the profile defined by all the intersected voxels, it returns:

• Profile position in object space (two XYZ points)
• Profile location in the data volume (two IJK indices)
• Number of values along the profile
• Each voxel value and corresponding IJK location

This class returns information about the data values in the picked voxels. SoVolumeRenderDetail also returns information about the mapped RGBA colors of the picked voxels.

GPU picking vs. CPU picking

VolumeViz can compute the picked voxel(s) and voxel colors on the GPU.
GPU picking is generally faster than CPU picking, but more importantly it is the only way to be sure of getting the correct result if the application is using a custom shader (see SoVolumeShader and VVizComputeFragmentColor) to compute voxel color and opacity. CPU picking always uses the color and opacity values assigned by the SoTransferFunction node. Therefore the result should be the same when using SoTransferFunction to assign color and opacity, but when using a custom shader the CPU picking algorithm is not able to know the color and opacity assigned by the shader.

Important: To enable GPU picking

• The realValue parameter must be false when calling the getXXX methods.
  
• The SoRayPickAction must be aware of the SoSceneManager.
  SoHandleEventAction does this automatically, so it is not necessary for the application to take any action when using an SoEventCallback node and calling the getPickedPoint() method. However if the application creates its own instance of SoRayPickAction, then it must call the method SoAction::setSceneManager() on that instance. If the scene manager is not specified, a warning message is issued and CPU picking is done.

Also be aware of the following trade-off. If the realValue parameter is set to false, the voxel value returned may be based on lower resolution (sub-sampled) data. The values should be approximately the same, but to be sure of getting values from the full resolution data, set the realValue parameter to true.

Limitations:

• If multiple volumes are being combined under an SoMultiDataSeparator, the detail class only returns values for the first volume in the scene graph.
• Because picking returns actual values of voxel, there may be a small difference between what you see on screen and what you get with picking. When visualizing a volume using LINEAR or CUBIC interpolation, you visualize interpolated data. Picking returns informations such as voxel value, voxel postion, etc... so picking return information of voxel values, not interpolated one. Visible areas may be not pickable and unvisibke areas may be pickable. When using NEAREST interpolation for rendering, picking matches what is displayed.

SEE ALSO

SoDetail, SoFenceSliceDetail, SoVolumeRenderDetail, SoVolumeSkinDetail, SoVolumeRender, SoVolumeSkin

Definition at line 123 of file SoVolumeDetail.h.

Constructor & Destructor Documentation

SoVolumeDetail()

SoVolumeDetail::SoVolumeDetail

(

)

Constructor.

~SoVolumeDetail()

virtual SoVolumeDetail::~SoVolumeDetail ( )

virtual

Destructor.

Member Function Documentation

copy()

virtual SoDetail * SoVolumeDetail::copy ( ) const

virtual

Returns an instance that is a copy of this instance.

The caller is responsible for deleting the copy when it is no longer needed.

Implements SoDetail.

Reimplemented in SoFenceSliceDetail, SoVolumeRenderDetail, and SoVolumeSkinDetail.

getClassTypeId()

static SoType SoVolumeDetail::getClassTypeId ( )

static

Returns the type identifier for this class.

getFirstNonTransparentValue() [1/2]

virtual SbBool SoVolumeDetail::getFirstNonTransparentValue ( double &  value, SbVec3i32 &  pos, SbVec3f *  objPos = 0, SbBool  realValue = FALSE  ) const

virtual

Retrieves the value and position of the first non-transparent voxel along the pick ray (if any).

Depending on the argument realValue, the voxel value is either fetched from the real value in full resolution data or fetched from the displayed data tile on the GPU which is not necessarily in full resolution. Fetching the data in full resolution may require a read from the disk if the full-resolution data is not currently in memory.

Parameters

[out]	value	the double value of the first non-transparent voxel along the pick ray.
[out]	pos	the position of the picked voxel in data space (IJK voxel coordinates)
[out]	objPos	the position of the picked voxel in object space (XYZ world coordinates).
[in]	realValue	if TRUE, the integer value is fetched from the full resolution data. If FALSE, it returns the voxel value from the (possibly subsampled) data currently in GPU memory, thus the voxel value that is displayed in the render area. The displayed voxel is not necessarily in full resolution.

Returns

FALSE if all voxels along the ray pick are fully transparent, thus all out parameters are meaningless

Warning

To use GPU picking, you must specify realValue = FALSE.

getFirstNonTransparentValue() [2/2]

virtual SbBool SoVolumeDetail::getFirstNonTransparentValue ( int64_t &  value, SbVec3i32 &  pos, SbVec3f *  objPos = 0, SbBool  realValue = FALSE  ) const

virtual

Retrieves the value and position of the first non-transparent voxel along the pick ray (if any).

Depending on the argument realValue, the voxel value is either fetched from the real value in full resolution data or fetched from the displayed data tile on the GPU which is not necessarily in full resolution. Fetching the data in full resolution may require a read from the disk if the full-resolution data is not currently in memory.

Parameters

[out]	value	the integer value of the first non-transparent voxel along the pick ray.
[out]	pos	the position of the picked voxel in data space (IJK voxel coordinates)
[out]	objPos	the position of the picked voxel in object space (XYZ world coordinates).
[in]	realValue	if TRUE, the integer value is fetched from the full resolution data. If FALSE, it returns the voxel value from the (possibly subsampled) data currently in GPU memory, thus the voxel value that is displayed in the render area. The displayed voxel is not necessarily in full resolution.

Returns

FALSE if all voxels along the ray pick are fully transparent, thus all out parameters are meaningless

Warning

To use GPU picking, you must specify realValue = FALSE.

getProfileDataPos()

int SoVolumeDetail::getProfileDataPos

(

SbVec3i32

profile[2]

)

const

Returns the number of values along the profile and the profile position in data space (voxel coordinates).

Specifically the profile parameter contains the IJK coordinates of the first and last points on the profile. The number of values is the number of of voxels intersected by the pick ray.

getProfileObjectPos()

void SoVolumeDetail::getProfileObjectPos

(

SbVec3f

profile[2]

)

const

Returns the profile position in object space (world coordinates).

Specifically the profile parameter contains the XYZ coordinates of the first and last points on the profile.

getProfileValue()

int64_t SoVolumeDetail::getProfileValue	(	int	index,
		SbVec3i32 &	pos,
		SbVec3f *	objPos = 0,
		SbBool	realValue = FALSE
	)		const

Returns the index'th value (as an integer) and its position in object and data space.

The number of values along the profile can be queried using the getProfileDataPos() method. However index is automatically clamped to the valid range of values.

If realValue is TRUE, VolumeViz will return the actual voxel value from the full resolution data. Note that this may require a read from disk if full resolution data is not currently in memory. If FALSE, VolumeViz will return the voxel value from the (possibly subsampled) data currently in memory.

Warning

To use GPU picking, you must specify realValue = FALSE.

getProfileValueD()

double SoVolumeDetail::getProfileValueD	(	int	index,
		SbVec3i32 &	pos,
		SbVec3f *	objPos,
		SbBool	realValue = FALSE
	)		const

Returns the index'th value (as a double) and its position in object and data space.

The number of values along the profile can be queried using the getProfileDataPos() method. However index is automatically clamped to the valid range of values.

If realValue is TRUE, VolumeViz will return the actual voxel value from the full resolution data. Note that this may require a read from disk if full resolution data is not currently in memory. If FALSE, VolumeViz will return the voxel value from the (possibly subsampled) data currently in memory.

Warning

To use GPU picking, you must specify realValue = FALSE.

getTypeId()

virtual SoType SoVolumeDetail::getTypeId ( ) const

virtual

Returns the type identifier for this specific instance.

Implements SoTypedObject.

Reimplemented in SoFenceSliceDetail, SoVolumeRenderDetail, and SoVolumeSkinDetail.

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

• VolumeViz/details/SoVolumeDetail.h