Create Dummy Partition

This Subflow creates a source and a target partition, which are subsequently used to filter features based on how they interact with these partitions. It is used to create the source and target partition for jobs running in National Load Mode or in Extent Only mode. These are derived from the extent of the job.

The Subflow contains two steps:

Create Dummy Source Partition

Create a PARTITION_SRC object with the same geometry as the job extent. 1Generalise will have created a job extent using a buffer of the target partition at an offset defined by the global parameter PartitionBufferOffset, simplified in such a way that no vertex is moved more than the global parameter PartitionBufferSimplificationTolerance. The buffer is required to make sure that all of the source features needed to generalise the content of the partition are loaded.

As the target partition has generalised boundaries, it is possible that some features (especially ones on the partition boundaries) are not intersecting the target boundary. The buffer should prevent that potential issue and it should be equal or larger than the maximum deviation allowed during the generalisation of partitioning features. The simplification tolerance is used to reduce the number of points in the geometry to speed up geometric comparisons.

Create Dummy Target Partition

This action creates a PARTITION_TGT object using the initial extent passed to the job. It is used to query and commit data from and to the target dataset.