Expanding short links
Regulator objects, such as pumps and valves, are modelled as links in InfoWorks WS Pro but are often stored as point objects in GIS. These point objects can be imported as links into InfoWorks WS Pro via the Open Data Import Centre. The imported links have zero length and coincident connecting nodes, which makes viewing the connectivity and orientation of these links on the GeoPlan window difficult.
The Expand Short Links tool can be used to expand the geometry of links with length below a specified value, improving the display and ability to interact with the link objects on the GeoPlan.
Methodology
For a selection of links, InfoWorks WS Pro checks for links below a specified length. If these 'short' links satisfy user defined constraints they are expanded to the specified length.
A short link is expanded by taking link geometry from connected links. If possible, an expanding link takes link bend geometry equally from its connected upstream and downstream links (constraints may cause a greater amount of length to be taken from one side). The connecting nodes to the short link will move, but the overall shape of the connecting links will be unchanged.
Constraints
There are a number of constraints that can affect or prevent the expansion of a link:
- The expansion of a link cannot move a node that is connected to more than two links.
- A connecting link cannot have its length reduced to below a user-specified minimum resultant length.
- If the option to protect customer connection points is set, geometry will not be taken from a link if it would result in the connection point of a customer point or spatial data point being moved.
Expanding links in InfoWorks WS Pro
To expand short links:
- Select the links to be considered for expansion on the GeoPlan window, or create a selection list of objects to be considered for expansion.
- Select Model | Expand short links. This displays the Expand Short Links dialog.
- On the Expand Short Links dialog, set the required options:
- In the Links to expand section, specify the links to be considered for expansion . A link will be considered for expansion if it satisfies all of the following conditions:
- The link is included in the Candidate links selection.
- The link type is checked in the Link type box.
- The link length is below or equal to the length specified in the Expand if length is below field .
- In the Protection of surrounding links section, set constraints for links connected to links to be expanded:
- Expansion will not occur if it would result in the length of a connecting link falling below the Minimum resultant length.
- If the Protect customer connection points option is checked, expansion will not occur if it would result in the connection point of a customer point or spatial data point being moved. If the option is unchecked, any affected connection points will be moved to the appropriate end of the link to which it is already allocated.
- Optionally set a user flag to be applied to modified fields.
Fields that the flag will be applied to are:
- Length field of modified links (only applied if Recalculate length; user flag option below is selected).
- X and Y coordinate fields of modified nodes.
- In the Modelling length of links section, select an option for recalculating the length of modified links:
- Retain previous length - retain length of link prior to expansion
- Recalculate length; #D flag - apply #D flag to Length field of modified links
- Recalculate length; user flag - recalculate length of modified links from geometry and apply selected user flag to Length field of modified links.
- Click the Expand button to carry out the expansion process.
An HTML log file is displayed containing details of modified objects and links rejected for modification.
Use the Select modified objects button to highlight modified links and moved nodes on the GeoPlan window.
Use the Select rejected links button to highlight links that were considered for expansion, but were not expanded due to one of the constraints listed above.
