FILTERKD

FILTER

FILTER/ELEMENT

This command is used to filter (mark for deletion) a set of nodes that are geometricly close, within the tolerance value. This command changes the node type of the deleted nodes to type ‘dudded’ (itp=21) but does not remove them from the point list. There must be least one point must be specified in the point range in order for this command to work properly.

Dudded nodes are not removed from the mesh object, but are ignored by many routines because of their dudded status. Use the command rmpoint/compress to remove dudded nodes and update the mesh object.

If the mesh object has connected elements, the itet values in the connectivity array are adjusted. This may change topology. To filter duplicate elements or flat elements, see filter/element or filterkd with the zero_element option.

FORMAT:

filterkd/ ifirst,ilast,istride/ [tolerance] / [nocheck OR zero_element]

filter/ ifirst,ilast,istride / [tolerance] / [ min OR max ] / attribute]

This version of filter is being replaced with the kd-tree search algorithm used in filterkd that more accurately identifies nodes within the tolerance value.

iirst,ilast,istride defines the node set where 1,0,0 are all nodes in the mesh object.

[tolerance]

This is the epsilon value used to measure node distances. If this value is not included, the mesh object epsilon value is used.

nocheck

This is the default for filterkd and will skip the code that removes zero elements. The behavior is similar to original filter except a kdtree structure is used instead of a binning method for finding nodes within epsilon value. This version has been shown to be more accurate where precision matters.

zero_element

This option is available with filterkd where a mesh has connected elements. The algorithm removes flat elements as using the tolerence value as mininum edge length. Duplicate nodes not associated with these flat elements are not removed.

minmax / attribute

This option is available with the filter command. Nodes for deletion are detected based on the standard geometric criteria however, the choice about which node is retained is determined based on comparison of the attribute values and the node with either the ** min** or ** max** value is retained.

filter/[element]/[search_range]/ [nodelete OR delete]

Search a mesh object for duplicate elements. A duplicate element is defined as having the exact same set of nodes in the element connectivity list (itet). The order of the nodes in the connectivity does not matter. The element with the larger itetclr value (master) wi ll be kept. The duplicate element will have its material color (itetclr) changed to max(itetclr) + 1. Two new element attributes (iclr1, iclr2) are added to the mesh object to keep track of the correspondence of master(retained)/duplicate(removed) elements and their original material id (itetclr).  The option nodeleteis the default and elements are not removed. Use option delete to remove the elements marked as duplicate. ]{style=”font-family: times;”

The search_range can be set by the user. This number limits the number of elements above and below an element (in numerical order) to search. The default is 10.

For more on filter/element see filter/element details.

 EXAMPLES:

filterkd/1,0,0

filter/1,0,0

Filter all nodes and delete duplicates with tolerance distance set to mesh object epsilon value. Both filter and filterkd behave the same but filterkd performs with better precision.

filterkd / 1 0 0 / 1.e-3

Filter all nodes and delete duplicates where epsilon tolerance is set by user to 1.e-3.

filterkd / [pset] / get_point_set

Filter a subset of the nodes and delete duplicates with epsilon tolerance set automaticly.

filterkd / 1 0 0 / 1.e-3 / zero_element

Identify and remove all flat elements with edge length less than 1.e-3 as defined by user.

filter / 1 0 0 / / min / imt

Filter all nodes and delete duplicates with epsilon tolerance set automaticly. When duplicate nodes are detected the imt attribute is examined and the node with minimum imt value is retained.

filter / [element]/ [nodelete]

Filter elements and set itetclr of duplicates to max(itetclr) + 1. Assign values to iclr1 and iclr2 arrays.

filter / [element] / 1e20 / [delete]

Filter all elements (assuming there are less than 1e20)  with an exhaustive search and delete duplicate elements. Assign values to iclr1 and iclr2 arrays.