Restrict blank with DTM

Select the Restrict blank with DTM option to decompose blocks based upon whether the blocks are above or below an existing DTM. No blocks will be created outside of the DTM.

Each block centre point in the block model file is projected onto the DTM. The Z value of the centre point is compared to the Z value of the DTM. The value written to the Code field for that point depends on whether the point is above or below the DTM.

Enter the name of the DTM file. If the DTM is a solid rather than a surface, the Side of DTM prompt allows you to specify whether a TOP or BOTTOM value is to be used when comparing values with Z values in the block model file.
Select a sub-blocking method.
Select Sub-blocks or Block factor and click the More button to decompose the blocks into sub-blocks to improve the accuracy of the assignment process. The blocks can be decomposed into ten sub-blocks in each direction.
If you selected the Block factor option, the Block Factor field input will be enabled. Enter the name of the block factor field. The portion of each block that falls above or below the DTM will be written to this field.
Enter the number of blocks, in each direction, into which the block will be subdivided. The more sub-blocks there are, the more accurate the assignment will be - at the expense of processing speed.
If you selected the Sub-blocks option, the On-fly optimise option will be enabled. The DTM assignment process can potentially make the blank output file very large. To optimise the size of the output file, select this option to create irregular blocks by aggregating sub-blocks according to their parent block.
Specify the name of the Code field and the values that will be written to the Code field to denote whether each block falls below or above the DTM.
Specify whether blocks above and/or below the DTM will be deleted from the blank output file.
If you selected the Block factor option, specify whether block factors will be written to those blocks above the DTM, or below the DTM.