- All Implemented Interfaces:
public class SoFenceSlice extends SoSliceFence slice shape node. This node renders a strip (connected series) of slices. The strip is defined by a set of 2D vertices that form a polyline. Each segment of the polyline is extruded along the axis specified in the
axisfield to form (in effect) an oblique slice. The default axis is Z, so the 2D points are treated as (X,Y) values. The points may be outside the 3D extent of the volume, but only the portion of the slice inside the volume will be drawn (subject to region of interest and other clipping nodes).
SoVolumeDatanode on which this shape is applied can be specified with
dataSetId. When this field is set to 0, the last
SoVolumeDatanode on state is used.
A similar effect could be obtained using volume geometry (e.g.
SoFenceSliceis more convenient and is optimized for this specific case.
The 2D coordinates are interpreted according to the following table. See the code example below.
Fence axis Coordinate axes X Y , Z Y Z , X Z X , Y
SoTransferFunction. The current diffuse color and transparency (set, for example, with an
SoMaterialnode) modify the appearance of the slice. This means that, for example, the current transparency can be used as a 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.
interpolationfield controls how the texture is interpolated.
SoSlice) controls how the voxel's alpha component is used when drawing the fence slice.
Optionally a bump mapping effect may be applied. Normal vectors are automatically computed from the data value gradient. The
SoSlice) control whether bump mapping is active and the intensity of the effect.
- 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.
The entire slice is pickable, even where it is transparent as a result of the current transfer function. Currently
SoFenceSlicedoes not provide an
Interpolation is specified using the
interpolationfield. 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
SoDataRangenode to specify the actual (or desired) range of data values to be mapped. Also use an
SoDataRangenode to implement brightness/contrast control like the Window/Level setting commonly used with medical images.
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.
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
SoMaterialnode before the slice and setting its diffuseColor field to full white (1,1,1).
- 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 slice rendering, but render the slice completely opaque, set the
alphaUsefield 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
- If you want to adjust the overall transparency of the slice, add an
SoMaterialnode and set its transparency field (keeping alphaUse set to ALPHA_AS_IS). 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
- Typically the color map (
- Voxel edges:
The edges of the voxels can also be rendered. See options in the
- Custom shaders:
SoVolumeShadernode, 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.
vec3 VVizTextureToTextureVec(in VVizDataSetId datasetSrc, in VVizDataSetId datasetDst, in vec3 texCoord);
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
SoTransformationnodes that are placed before the
SoDataSetnode in the order of the traversal.
- 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
SoVolumeRenderbut 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
SoConverterand the "-t" option). For other data data formats the tile size can be specified using the
SoVolumeDatanode's ldmResourceParameters field, but only after setting the filename field or calling the setReader() method.
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.
- Tile size:
- Hardware requirements:
This node needs a graphic card with support for GLSL shader, vertex buffer objects (VBO) and framebuffer object (FBO). Use the
isSupported()method to check if the current graphics board can render a FenceSlice.
SoObliqueSlicefor a complete code example. The following shows how to set up the
SoFenceSlice fenceSlice = new SoFenceSlice(); fenceSlice.axis.setValue( SoFenceSlice.AxisType.Y ); fenceSlice.points.set1Value( 0, new SbVec2f(-0.2f, -0.66f) ); fenceSlice.points.set1Value( 1, new SbVec2f( 0.2f, -0.4f ) ); fenceSlice.points.set1Value( 2, new SbVec2f(-0.2f, 0.4f ) ); fenceSlice.points.set1Value( 3, new SbVec2f( 0.2f, 0.66f) ); Fence slice on Y axis (Colt example data set): Fence slice on X axis (Colt example data set): Fence slice on Z axis (Colt example data set):
dataSetId 0 points [ ] axis Z interpolation LINEAR alphaUse ALPHA_BINARY useRGBA false alternateRep NULL enableBumpMapping false bumpScale 1.0
Draws a textured shape based on current
Computes the bounding box that encloses the fence slice.
Nested Class Summary
Nested Classes Modifier and Type Class Description
Nested classes/interfaces inherited from class com.openinventor.volumeviz.nodes.SoSlice
Nested classes/interfaces inherited from class com.openinventor.volumeviz.nodes.SoVolumeShape
Nested classes/interfaces inherited from class com.openinventor.inventor.nodes.SoShape
Nested classes/interfaces inherited from class com.openinventor.inventor.nodes.SoNode
Nested classes/interfaces inherited from class com.openinventor.inventor.Inventor
Fields Modifier and Type Field Description
axisExtrusion axis: X, Y, or Z.
SoVolumeDatanode to use.
pointsSet of points defining a lineset.
Fields inherited from class com.openinventor.volumeviz.nodes.SoSlice
alphaUse, alternateRep, bumpScale, enableBumpMapping, largeSliceSupport, useRGBA
Fields inherited from class com.openinventor.volumeviz.nodes.SoVolumeShape
Fields inherited from class com.openinventor.inventor.nodes.SoShape
Fields inherited from class com.openinventor.inventor.Inventor
Constructors Constructor Description
All Methods Static Methods Concrete Methods Modifier and Type Method Description
isSupported(SoState state)Returns true if graphic card can render an
Methods inherited from class com.openinventor.inventor.nodes.SoShape
getShapeType, isPrimitiveRestartAvailable, isPrimitiveRestartAvailable
Methods inherited from class com.openinventor.inventor.nodes.SoNode
affectsState, callback, copy, copy, distribute, doAction, getAlternateRep, getBoundingBox, getByName, getMatrix, getPrimitiveCount, getRenderEngineMode, getRenderUnitID, GLRender, GLRenderBelowPath, GLRenderInPath, GLRenderOffPath, grabEventsCleanup, grabEventsSetup, handleEvent, isBoundingBoxIgnoring, isOverride, pick, rayPick, search, setOverride, touch, write
Methods inherited from class com.openinventor.inventor.fields.SoFieldContainer
copyFieldValues, copyFieldValues, enableNotify, fieldsAreEqual, get, getAllFields, getEventIn, getEventOut, getField, getFieldName, hasDefaultValues, isNotifyEnabled, set, setToDefaults
Methods inherited from class com.openinventor.inventor.misc.SoBase
dispose, getName, isDisposable, isSynchronizable, setName, setSynchronizable
Methods inherited from class com.openinventor.inventor.Inventor
public final SoSFInt32 dataSetIdSpecifies the
SoVolumeDatanode to use. This is useful when datasets of different dimensions are present in the scene graph. Please see
SoMultiDataSeparatorfor more details.
When set to 0, the last
SoVolumeDatanode on state is used. Default is 0.
- Open Inventor 10.11.0
public final SoMFVec2f pointsSet of points defining a lineset.
- X: points are Y,Z coordinates
- Y: points are Z,X coordinates
- Z: points are X,Y coordinates
All points should be inside the 3D extent of the volume.
public final SoSFEnum<SoFenceSlice.AxisType> axisExtrusion axis: X, Y, or Z. . Default is Z.
public static boolean isSupported()Calls isSupported((com.openinventor.inventor.misc.SoState)null).
public static boolean isSupported(SoState state)Returns true if graphic card can render an
SoFenceSlice. GPU must support GLSL. When using a debug build of Open Inventor, some "no context available" warning messages may be generated. You can ignore them or see
SoGLExtensionfor an example of using
SoGLContextto avoid them.