Feature Object Tools

This tool is used to create a grid frame. The placement and size of the grid frame is defined by three clicks on the screen in the Graphics Window. The first click defines the grid origin, the second defines the bottom edge of the grid, and the third defines the perpendicular extent of the grid.

The Create Point tool is used to interactively create new points. A new point is created for each location the cursor is clicked on in the Graphics Window. Once the point is created, it can be repositioned or otherwise edited with the Select Point/Node tool.

The Create Vertex tool is used to interactively create new vertices along an existing arc. This is typically done to add more detail to the arc. A new vertex is created for each location the cursor is clicked on in the Graphics Window that is within a given pixel tolerance of an existing arc. Once the vertex is created, it can be repositioned with the Select Vertex tool.

The Create Arc tool is used to interactively create new arcs. An arc is created by clicking once on the location where the arc is to begin, clicking once to define the location of each of the vertices in the interior of the arc, and double-clicking at the location of the end node of the arc.

As arcs are created, it is often necessary for the beginning or ending node of the arc to coincide with an existing node. If you click on an existing node (within a given pixel tolerance) when beginning or ending an arc, that node is used to define the arc node as opposed to creating a new node. If you click on a vertex of another arc while creating an arc, that vertex is converted to a node and the node is used in the new arc. If you click within a given tolerance of an arc edge, a new node is inserted in the arc. If you click on an existing point while creating an arc, the point is converted to a vertex, unless it is the beginning or ending location of an arc, in which case it is converted to a node.

While creating an arc, it is common to make a mistake by clicking on the wrong location. In such cases, hitting the Backspace key backs up the arc by one vertex. The ESC key can also be used to abort the entire arc creation process at any time.

This tool is used to select and edit the grid frame. Once the grid frame is selected, the placement and size of the grid frame can be edited by clicking on small rectangles and dragging.

The Select Point/Node tool is used to select existing points or nodes. A selected point/node can be deleted, moved to a new location, or operated on by one of the commands in the Feature Objects menu. The coordinates of selected points/nodes can be edited using the Edit Window. Double-clicking on a point or node with this tool brings up the Point or Node Attribute dialog.

The Select Vertex tool is used to select vertices on an arc. Once selected, a vertex can be deleted, moved to a new location, or operated on by one of the commands in the Feature Objects menu. The coordinates of a selected vertex can be edited using the Edit Window.

The Select Arc tool is used to select arcs for operations such as deletion, redistribution of vertices, or building polygons. Double-clicking on an arc with this tool brings up the Arc Attributes dialog.

The Select Arc Group tool is used to select an arc group to assign attributes or to display the computed flux on the arc group. An arc group is created by selecting a set of arcs and selecting the Create Arc Group command. An arc group is deleted by selecting the arc group and selecting the Delete key or by selecting the Delete command in the Edit menu. Deleting an arc group does NOT delete the underlying arc objects.

The Select Polygon tool is used to select previously created polygons for operations such as deletion, assigning attributes, etc. A polygon is selected by clicking anywhere in the interior of the polygon. Double-clicking on a polygon with this tool brings up the Polygon Attributes dialog.