About attributes for reblocking

The attributes and attribute values in a reblocked model are based on the attributes and values in the source block model.

The Block Model Converter creates the reblocked model as a multiple percentile block model, using only floating-point attribute types.

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Due to the way attribute values are assigned and the differences in block dimensions in the reblocked model, there is potential for differences between the original set of attributes and attribute values and the attributes and values that result from reblocking.

There is a natural side effect from the reblocking process which can cause the volume, mass, or grade values for the new blocks to differ from the original value. This effect occurs when you combine values from multiple blocks to calculate the value for a new (reblocked) model. If the new blocks are larger than the blocks in the source block model, there will be some loss of spatial precision (that is, spatial knowledge of exactly where a certain material type or grade is located in the block). Although this loss of precision may not be acceptable for all purposes, it is an unavoidable consequence of the reblocking process.

You set the attributes for reblocking in the Reblocking Attributes tab.

Reblocking Attributes tab

Columns in the Reblocking Attributes tab

Column	Description
Include	Select this check box to include the attribute in the reblocked model.
Attribute Name	The name of the attribute. Display-only.
Type	The type of attribute. Display-only.
Default Value	The default value of the attribute. Display-only.
Replacement Value	The value to replace the default attribute value used in the reblocking calculations or if no value is provided.
Calculation Method	The method to calculate the values of the attributes in the blocks of the reblocked model. For string and integer attributes, the options are: Highest Frequency: The attribute value that has the largest volume is assigned to the attribute in the reblocked model. Multi-Percentage: The attribute is a category for a multi-percentage reblock. Note: When you select this calculation method, you must select at least one other attribute with a calculation that is not Multi-Percentage. For numeric attributes, the options are: Aggregate: Aggregates all the values of the attribute for the reblocked model. Aggregate Ignore Negatives: Aggregates all the values of the attribute but ignores the negative values for the reblocked model. Aggregate Replace Background: Aggregates all the values of the attribute and replaces the background (default) value with the Replacement Value for the reblocked model. Aggregate Replace Negatives: Aggregates all the values of the attribute and replaces negative values with the Replacement Value for the reblocked model. Average: Takes the average of the values from the affected source blocks, weighted by the attribute selected in the Weight By column for the reblocked model. Average Ignore Negatives: Takes the average of the values from the affected source blocks, weighted by the attribute selected in the Weight By column and ignores blocks with negative values for the reblocked model. Average Replace Background: Takes the average of the values from the affected source blocks, weighted by the attribute selected in the Weight By column and replaces the background (default) value with the Replacement Value for the reblocked model. Average Replace Negatives: Takes the average of the values from the affected source blocks, weighted by the attribute selected in the Weight By column and replaces negative values with the Replacement Value for the reblocked model. For more information about the calculation methods, see See "About reblocking and attributes of multiple percentile block models".
Weight By	The attribute to use as a weighting value for the average calculation methods. If you select the <none> option, the attribute is weighted by volume. This column is available only when the Calculation Method is set to any of the average calculation methods. Tip: This value is usually the density or a specific gravity attribute.

About string attributes

A string attribute belongs to a group and/or a category. A group can have one ore more categories. For example, in the source block model there is a string attribute "material" with values of "ore" and "waste". The Block Model Converter identifies a group named "material" with categories of "ore" and "waste". Each group also has an unclassified category to calculate portions of a block in the reblocked block model that may not be applicable to any of the categories. The label for the unclassified category is set in the Options dialog box.

Attributes of the reblocked model

The reblocked model has attributes for each group/category/floating point attribute combinations.

The name of the new attribute is constructed by concatenating these three items:

• the name of the group
• the name of the category
• one of the following: density (or specific gravity), fraction, or the selected floating point attribute name

Note: If the average calculation method is used and a weight-by attribute is provided for the floating point attribute name, its associated weight-by attribute name is also included.

For example, if the "material" group has the "ore" and "waste" categories and the "mined" floating point attribute included, then the following attributes are created in the reblocked model:

material_ore_mined

material_waste_mined

material_unclass_mined

Each group also has a fractional attribute to define the percentage of the new block to which the calculated attribute value applies. This value does not appear in the tree view, but it is generated in the block model data that results from reblocking. The label for the fractional attribute is set in the Options dialog box.

See also

• Set attributes for reblocking
• Set dimensions for reblocking