```{index} single: Filters; Merge Twins
```
# Merge Twins

## Group (Subgroup)

Reconstruction (Grouping)

## Description

*THIS FILTER ONLY WORKS ON CUBIC-HIGH (m3m) Laue Classes.*

This **Filter** groups neighboring **Features** that are in a twin relationship with each other (currently only FCC &sigma; = 3 twins).  The algorithm for grouping the **Features** is analogous to the algorithm for segmenting the **Features** - only the average orientation of the **Features** are used instead of the orientations of the individual **Elements**.  The user can specify a tolerance on both the *axis* and the *angle* that defines the twin relationship (i.e., a tolerance of 1 degree for both tolerances would allow the neighboring **Features** to be grouped if their misorientation was between 59-61 degrees about an axis within 1 degree of <111>, since the Sigma 3 twin relationship is 60 degrees about <111>).


### Random Number Seed Parameters

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Use Seed for Random Generation | Bool |  | When true the user will be able to put in a seed for random generation |
| Seed Value | Scalar Value |UInt64 | The seed fed into the random generator |
| Stored Seed Value Array Name | DataObjectName |  | Name of array holding the seed value |

### Input Parameter(s)

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Axis Tolerance (Degrees) | Scalar Value |Float32 | Tolerance allowed when comparing the axis part of the axis-angle representation of the misorientation |
| Angle Tolerance (Degrees) | Scalar Value |Float32 | Tolerance allowed when comparing the angle part of the axis-angle representation of the misorientation |

### Input Cell Data

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Cell Feature Ids | Array Selection | Allowed Types: int32 Comp. Shape: 1 | Specifies to which Feature each cell belongs |

### Input Feature Data

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Contiguous Neighbor List | NeighborListSelection |  | List of contiguous neighbors for each Feature. |
| Phases | Array Selection | Allowed Types: int32 Comp. Shape: 1 | Specifies to which Ensemble each cell belongs |
| Average Quaternions | Array Selection | Allowed Types: float32 Comp. Shape: 4 | Specifies the average orientation of each Feature in quaternion representation |

### Input Ensemble Data

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Crystal Structures | Array Selection | Allowed Types: uint32 Comp. Shape: 1 | Enumeration representing the crystal structure for each Ensemble |

### Output Element Data

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Parent Ids | DataObjectName |  | The name of the array specifying to which parent each cell belongs |

### Output Feature Data

| Parameter Name | Parameter Type | Parameter Notes | Description |
|----------------|----------------|-----------------|-------------|
| Feature Attribute Matrix | DataObjectName |  | The name of the created cell feature attribute matrix |
| Parent Ids | DataObjectName |  | The name of the array specifying to which parent each Feature belongs |
| Active | DataObjectName |  | The name of the array specifying if the Feature is still in the sample (true if the Feature is in the sample and false if it is not). At the end of the Filter, all Features will be Active |

## Example Pipelines

+ (10) SmallIN100 Full Reconstruction
+ (06) SmallIN100 Postsegmentation Processing

## License & Copyright

Please see the description file distributed with this **Plugin**

## DREAM3D-NX Help

If you need help, need to file a bug report or want to request a new feature, please head over to the [DREAM3DNX-Issues](https://github.com/BlueQuartzSoftware/DREAM3DNX-Issues/discussions) GitHub site where the community of DREAM3D-NX users can help answer your questions.