Expanding Short Links

Objects that are modelled as links in InfoWorks ICM may be stored as point objects in GIS. These point objects can be imported as links into InfoWorks ICM 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 ICM 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

Expanding Links in InfoWorks ICM

To expand short links:

1. Select the links to be considered for expansion on the GeoPaln Window, or create a Selection List of objects to be considered for expansion.
2. Select Geometry | Expand short links from the Model menu. This displays the Expand Short Links Dialog.
3. Set the required options on the Expand Short Links Dialog:
• Specify the links to be considered for expansion in the Links to expand section. 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
• Set constraints for links connected to links to be expanded in the Protection of surrounding links section:
• Expansion will not occur if it would result in the length of a connecting link falling below the Minimum resultant length
• 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
• Select an option for recalculating the length of modified links in the Modelling length of links section:
• 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.
4. 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 View.

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.