| SoMultiscaleStructureEnhancementProcessing2d Class |
OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d engine.
Inheritance HierarchyOIV.InventorSoNetBase
OIV.InventorSoDisposable
OIV.Inventor.MiscSoBase
OIV.Inventor.FieldsSoFieldContainer
OIV.Inventor.EnginesSoEngine
OIV.ImageViz.EnginesSoImageVizEngine
OIV.ImageViz.Engines.ImageFiltering.TextureFiltersSoMultiscaleStructureEnhancementProcessing2d
Namespace: OIV.ImageViz.Engines.ImageFiltering.TextureFilters
Assembly: OIV.ImageViz (in OIV.ImageViz.dll) Version: 2023.1.3.0 (2023.1.3)
SyntaxThe SoMultiscaleStructureEnhancementProcessing2d type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | SoMultiscaleStructureEnhancementProcessing2d | Constructor. |
Methods| Name | Description | |
|---|---|---|
| AbortEvaluate | Abort current processing as soon as possible. |
| Copy | Creates and returns an exact copy of the engine. |
| CopyFieldValues(SoFieldContainer) | Calls CopyFieldValues(fc, false). (Inherited from SoFieldContainer.) |
| CopyFieldValues(SoFieldContainer, Boolean) | Copies the contents of fc's fields into this object's fields. |
| Dispose |
Releases all resources used by SoDisposable.
(Inherited from SoDisposable.) |
| EnableNotify | Notification at this Field Container is enabled (if flag == true) or disabled (if flag == false). |
| Equals | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
| FieldsAreEqual | Returns true if this object's fields are exactly equal to fc's fields. |
| Get | Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string. |
| GetAllFields | Returns a list of fields, including the eventIn's and eventOut's. |
| GetEventIn | Returns a the eventIn with the given name. |
| GetEventOut | Returns the eventOut with the given name. |
| GetField | Returns a the field of this object whose name is fieldName. |
| GetFieldName | Returns the name of the given field in the fieldName argument. |
| GetFields | Appends references to all of this object's fields to resultList, and returns the number of fields appended. |
| GetHashCode |
Overrides GetHashCode().
(Inherited from SoNetBase.) |
| GetName | Returns the name of an instance. |
| GetOutput | Returns a reference to the engine output with the given name. |
| GetOutputName | Returns (in outputName) the name of the engine output (output). |
| GetOutputs | Returns a list of outputs in this engine. |
| GetStringName | (Inherited from SoBase.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| HasDefaultValues | Returns true if all of the object's fields have their default values. |
| IsEvaluating | Returns true if the engine evaluation is in progress. |
| IsNotifyEnabled | Notification is the process of telling interested objects that this object has changed. |
| IsSynchronizable | Gets the ScaleViz synchronizable state of this object. |
| Set | 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. |
| SetName | (Inherited from SoBase.) |
| SetSynchronizable | Sets this to be a ScaleViz synchronizable object. |
| SetToDefaults | Sets all fields in this object to their default values. |
| StartEvaluate | Evaluate engine and dependencies in another thread without blocking the current one. |
| ToString |
Converts this SoBase structure to a human readable string.
(Inherited from SoBase.) |
| Touch | Marks an instance as modified, simulating a change to it. |
| WaitEvaluate | Wait for the end of engine evaluation. |
Properties| Name | Description | |
|---|---|---|
 | inImage | Input image. |
| IsDisposable | ISafeDisposable interface implementation.
(Inherited from SoDisposable.) |
| lightness | The lightness type of structures to enhance. |
| outImage | Output image. |
| standardDeviationRange | Standard deviation of the Gaussian kernel at minimum and maximum scale. |
| standardDeviationStep | Standard deviation step. |
| structureType | Shape of structures to extract. |
| tensorType | Defines whether the command will use the gradient tensor or the hessian matrix. |
| UserData |
Gets or sets the user data to be contained by the field container.
(Inherited from SoFieldContainer.) |
Events| Name | Description | |
|---|---|---|
 | OnBegin | Event raised when the processing begins. |
| OnEnd | Event raised when processing ends and the result is available. |
| OnProgress | Event raised while processing is running. |
RemarksOverview
The purpose of this algorithm is to enhance structures of interest from an image using a multi scale analysis. The result of this algorithm is a score image that can be used with the goal of segmenting the input image.
The SoMultiscaleStructureEnhancement filters compute a score between 0 and 1 for each pixel, 1 representing a good matching with a structure model and 0 a background pixel. This provides a powerful technique for automatically identifying structures such as blood vessels. The score can be computed either on an Hessian matrix to detect ridge structures or on a Gradient tensor for object edges and corners. The structure models available are:
Balls (circular structures with Hessian in 2D, spherical in 3D, object corners with Gradient tensor)
Rods (linear structures)
Plates (only available in 3D)
The principle of the algorithm can be summarized as follows :
A set of tensor fields is extracted from the image by filtering the image at different scales.
A score image is extracted from each tensor field by analyzing the eigenvalues of tensors.
The final score is obtained by selecting the maximum of all score images.
The following publication describes this algorithm when applied to detect Rod structures with the Hessian matrix: A.F.Frangi, W.J.Niessen, K.L.Vincken, M.A.Viergever, "Multiscale vessel enhancement filtering", Lecture Notes in Computer Science(MICCAI), vol. 1496, pp. 130-137, 1998.
Tensor Extraction
2 modes are available for computing the tensor field; the OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.GRADIENT mode and the OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.HESSIAN mode. The first one is based on the gradient tensor, the second one on the hessian matrix.
OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.GRADIENT mode
In the OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.GRADIENT mode, the gradient tensor is extracted. This tensor also referred to as structure tensor or second order moment matrix, is a matrix derived from the gradient of the image. This matrix summarizes the predominant directions of the gradient around the voxel of interest.
Where 
is a gaussian kernel controlling the scale of analysis.
OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.HESSIAN mode
In this mode, the tensor field is based on the extraction of the hessian matrix of the image. This hessian matrix is computed by filtering the image with the derivative of a gaussian kernel. The standard deviation of the kernel controls the scale of analysis.
Feature extraction
The parameter structureType controls the type of structure that is extracted from the tensor field (ROD/BALL). Let 
be the 2 eigenvalues of the extracted tensor.
The score for StructureType2D.ROD corresponds to :
This score favors anisotropic tensors.
The score for StructureType2D.BALL structures is computed as follows :
This score favors isotropic tensors.
where 
is the tensor norm, 
is a threshold which controls the blobness sensitivity, and c is a sensitivity threshold which controls the noise influence. 
with 
the maximum Hessian norm in the image.
In the OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.HESSIAN mode, the lightness parameter limits the feature extraction to dark or bright objects by analyzing the sign of eigenvalues. This parameter is ignored in OIV.ImageViz.Engines.ImageFiltering.TextureFilters.SoMultiscaleStructureEnhancementProcessing2d.TensorTypes.GRADIENT mode where tensors are positive definite matrices.
The table below summarizes enhanced feature according to the parameters
| Structure Type |  |  | detected feature in GRADIENT mode | detected feature in HESSIAN mode | |
| ROD | strong | weak | straight edge | ridge | |
| BLOB | strong | strong | edge corner/blob | blob |
FILE FORMAT/DEFAULT
MultiscaleStructureEnhancementProcessing2d {
| inImage | NULL |
| tensorType | HESSIAN |
| standardDeviationRange | 1.0f 3.0f |
| standardDeviationStep | 1.0f |
| lightness | BRIGHT |
| structureType | ROD |
Library references: structureenhancementfilter
See Also