Edge Match Dialog

Edge Match Dialog - Not available with the version for ArcView 3.0

15012001em_link_dg.jpg (14458 bytes)

Edgematching is done to ensure that features are aligned along the edges of adjoining shape files.

The Edgematching process uses three themes:

edit theme - the theme whose features will be adjusted

snap theme - a theme whose features are used as the control points for moving edit theme features.

link theme - a polyline theme that contains the links to be used for edge matching

The link theme can be:

an existing in the current view polyline theme. The polylines should be a single segmented.
imported from a table. The table must have at least four numeric fields representing the X and Y coordinates of the START and END point of a LINK
Create button in the Link Theme control panel will create a new LINK theme and will introduce the Edit Link Theme dialog
Edit button in the Link Theme control panel will introduce the Edit Link Theme dialog

Edit Link Theme Dialog has three tools for editing a LINK theme

Generate Links Tool - the user draws a polygon including the edges of the EDIT and Snap themes. If a node from the EDIT theme is closer to a node from the SNAP theme than the specified tolerance a link is created connecting the two nodes.

15012001em_gen_links.jpg (13185 bytes)

Add Link Tool - the user draws a line (link) using selected snap method and tolerance
Delete Links Tool

Edge Matching Methods:

Snap: Moves the nodes from the EDIT theme associated with links to snap to the corresponding nodes from the SNAP theme

Before Edge Match	After Edge Match

Adjust: Rubber sheets the position of polylines using the link theme
- Only the vertices within user defined adjust area are moved
- The influence area of the links is defined by a Thiessen polygons build from the Start point of the links
- The vertices within the influence area of a link are moved in the direction of the displacement vector defined by the link
- The length of the displacement vector for a vertex is defined by the distance from the vertex to the start point of the link. The bigger the distance, the smaller the displacement.
- The user can specify the adjustment area using (preview available)
  - buffered Convex Hull polygon - defined from the start points of the links
  - buffered start points of the links

NOTE: In some cases using ADJUST function produces better results

Buffered Convex Hull	Buffered Points	Areas of influence

Before Edge Match	After Edge Match