About block models
Block models are made up of a three-dimensional grid of blocks where no blocks overlap each other in the same model.
A block model has an associated set of attribute values where one value of each attribute is assigned to each block in the model. The value is a character string, integer (of various lengths), float, or double. Often a default value for each attribute is assigned to blocks when a specific value is not provided.
Typically, the coordinates of the blocks are provided as X, Y, Z values, with X and Y being the 2D (horizontal) coordinates of the block and Z being the layer of the block in the grid (depth). To fully define any given block, at a minimum, the coordinates of one of the corners and the dimensions of the block must be provided. The coordinates are relative to the origin of the block model, which is typically the lower left front corner of the model (although the origin may be outside of the bounds of the model itself). Not all software applications use the same origin, particularly in the z-axis; the origin is sometimes the upper left front corner.
The material within a block is homogenous except when dealing with percentile models. Multiple material types, using a user-defined categorisation rule, are represented using multiple percentile values (which must not sum to greater than 100%). However, the geometric location of each of the proportions is not known. Percentile models are suited to some downstream modeling processes but require specific capabilities within the block modeling applications to appropriately deal with the multiple percentile values.