8.88. Map Point Cloud to Regular Grid

Group (Subgroup)

Sampling (Mapping)

Description

This Filter determines, for a user-defined grid, in which voxel each point in a Vertex Geometry lies. The user can either construct a sampling grid by specifying the dimensions, or select a pre-existing Image Geometry to use as the sampling grid. The voxel indices that each point lies in are stored on the vertices.

Additionally, the user may opt to use a mask; points for which the mask are false are ignored when computing voxel indices (instead, they are initialized to voxel 0).

One of the features provided to the user is control over the value used when a point is Out-of-Bounds. The three options are:

• Silent: (default) Will silently use the user supplied value

• Warning with Count: Will emit a filer warning that contains the number of out-of-bounds values were encountered.

• Error at First Instance: Will emit a filter error at the out-of-bounds value that is encountered.

The default selection is Silent, but it is mostly provided as a way to preserve existing functionality. What follows are a few use cases we had in mind when adding this functionality, organized by handling type:

• Silent option:

  • User may want to preserve identical functionality between SIMPL and simplnx

  • User may expect values to fall outside the target image geometry or intend to crop all that fall outside it anyway

• Warning with Count option:

  • User may be intending to create a general use pipeline for various different tasks, for which monitoring and validation may be important

  • User may intend to create a workflow that will be distributed in which the end user may not have control over the parameter, but should be monitoring for anomalies in output

  • User may want to watch for unexpected behavior

• Error at First Instance option

  • User may to trace down where a anomaly first occured

  • User may be creating a pipeline in a known problem space with a well defined outcome where any data anomalies must be caught early to prevent downstream problems

Continuing along the Out-of-Bounds discussion, the Out-of-Bounds value allows the user to specify a specific uint64 (0 - 18,446,744,073,709,551,616) value to use for every value from the vertex geometry that falls outside the image geometry. The default value is just the max unsigned long long int in an effort to make sure that it doesn’t intersect with exisiting indexed values. This is identical to previous functionality. However, consider the situation where a user has a geometry that contains 1000 voxels, in this case the actual index values are 0-999, so a user could select 1000 and it wouldn’t overlap any existing voxel index. Doing this may reduce skew of coloring or other statistic-based analysis. Advanced users may intentionally select a value that overlaps an existing voxel index they wish to remove in a later filter or to later downcast the datasize without overflow, but this is considered an edge case that is functional, but not recommended.

Sampling Grid Selection

Parameter Name	Parameter Type	Parameter Notes	Description
Sampling Grid Type	Choices		Specifies how data is saved or accessed
Grid Dimensions	Vector of Int32 Values	Order=X,Y,Z	Target grid size
Created Image Geometry	DataGroupCreation		Path to create the Image Geometry
Existing Image Geometry	Geometry Selection	Image	Path to the existing Image Geometry
Out of Bounds Handling	Choices		Specifies how data outside the image bounds is handled, see documentation for specification
Out of Bounds Value	Scalar Value	UInt64	The value to be put in voxel indices slots, occurs when the vertex geometry’s coordinate point falls outside the image geometry’s bounds

Input Vertex Geometry

Parameter Name	Parameter Type	Parameter Notes	Description
Vertex Geometry	Geometry Selection	Vertex	Path to the target Vertex Geometry

Optional Data Mask

Parameter Name	Parameter Type	Parameter Notes	Description
Use Mask Array	Bool		Specifies whether or not to use a mask array
Mask	Array Selection	Allowed Types: uint8, boolean Comp. Shape: 1	DataPath to the boolean/uint8 mask array. Values that are true will mark that cell/point as usable.

Output Data Object(s)

Parameter Name	Parameter Type	Parameter Notes	Description
Created Voxel Indices	DataObjectName		Path to the created Voxel Indices array
Created Cell Data Name	DataObjectName		The name of the cell data attribute matrix to be created within the created Image Geometry

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 GitHub site where the community of DREAM3D-NX users can help answer your questions.