Features

Architecture

JCS is designed to provide easy access to conflation algorithms both interactively and programmatically.  All conflation algorithms are exposed as APIs, which can be used in scripted processing or in other applications.  JCS uses the JUMP Workbench and API to provide visualization, support for interactive workflow, and spatial data processing.  JCS uses the JTS Topology Suite to provide basic geometric functionality.

Coverage Cleaning

JCS provides algorithms to detect and correct topology errors in coverages.  Coverage errors consist of overlaps and gaps which cause a dataset to fail to have correct coverage topology.  JCS can detect both gaps and overlaps and display them to allow manual inspection.  An algorithm is provided which is able to fix most gaps and overlaps automatically.  Interactive snapping tools are also provided to allow errors to be removed manually.

	Running the Find Gaps QA tool on a dataset containing coverage errors
	Running Remove Coverage Gaps to remove coverage gaps automatically
	Using the Snap Vertices Tool to manually fix a gap error
	Results of removing a gap error with the Snap Vertices Tool

Boundary Alignment

Boundary Alignment is an example of horizontal conflation of coverages.  It may be intended that two adjacent datasets should form a single consistent coverage.  Gaps and overlaps along the shared boundary can prevent the datasets from having correct coverage topology.  JCS provides tools to detect, display, and correct these boundary alignment errors.

QA tools for Boundary Alignment, showing detection and display of gaps along the boundary between two coverages

Coverage Alignment

Coverage Alignment is an example of Vertical conflation.  It consists of aligning the edges of a Subject coverage to the edges of a Reference coverage that partially or completely overlaps the Subject.  JCS provides tools to detect and display alignment errors.  It provides an algorithm which can automatically fix most alignment errors.  For errors which cannot be fixed automatically JCS provides snapping tools to allow manually fixing the error.

QA tools for Coverage Alignment, showing detection and display of alignment errors between coverages of suburb boundaries and lot parcels

Road Network Matching

The conflation of road networks involves matching two different versions of the same road network to determine which edges (road sections) match.  Once this matching has been established, attributes can be transferred between matching road sections, and missing road sections can be added from one network to another.  JCS provides an algorithm to automatically establish node and edge matchings between two road networks.  Where the automatic algorithm is unable to determine a match, manual tools are provided to create and delete matches.  The resulting matching can be output to be used in further processing.

Road Network Matching can automatically match road edges between two versions of the same road network.

Precision Reduction

Spatial datasets can sometimes contain coordinates with excess precision, as a result of data capture methods or format translation.  JCS contains a function which reduces the precision of dataset coordinates to a given number of decimal places or by a given factor.  Reducing precision can cause geometry topology to become invalid; in this case JCS provides an error report showing the location of the errors, thus allowing them to be identified and fixed if necessary.

Results of running Precison Reduction on a dataset, showing rounded values of coordinates.

Geometry Difference Detection