A new vector layer is created whenever a vector segment is loaded from a file or when the "New Layer" button is selected in the "Operation" section of the Vector Editor.
A list of the currently loaded vector layers appears at the top of the Vector Editor, with the currently selected layer shown highlighted. Editing operations can take place on only one layer at a time. If a layer is not visible in the graphic plane (image window) it is automatically made visible upon selection.
The "Operation" section of the Vector Editor contains all of the vector editing operations which can be performed on the layer. An operation button is disabled if the operation is not valid or cannot be performed for the current layer or shape. If an operation is taking place, that operation's button is pressed in. Selecting the depressed button will end or cancel the operation.
A vector layer contains shapes which are also referred to as vectors. Each shape in the layer has a unique shape id number and can have zero or more vertices. If a shape has no vertices, it is not visible in the graphic plane. A shape with only one vertex is a point and is represented in the graphic plane by small crosshairs which intersect at the location of the point. A shape with more than one vertex is represented by a polyline.
The "Current Shape" section of the Vector Editor shows information about the currently selected shape. The information in this section of the panel is filled in only if there is a single current shape.
If there is a single current shape, the "Shape ID" text field displays its id number. For the current shape, there may also be a currently selected vertex which is shown in the "Vertex ID" text field. The total number of vertices in the current shape is displayed beside the current vertex id.
The "Position" section of the Vector Editor shows the current vertex's x, y, and z coordinates in the layer's georeferenced units. The vertex position can be modified by making changes in the X, Y, and Z text fields. If the shape has no vertices, then these text fields are blank.
Next to the ``Position'' section are the area and length of the shape, also provided in the layer's georeferenced units. If the shape is not closed, the area is blank. A shape is considered closed if its first vertex and last vertex have the same position coordinates. The area may not be accurate for a complex closed shape such as one with crossing edges. If the current shape has no vertices, then the length is also blank.
Below the length is the attribute field section of the panel. A vector layer may have any number of attribute fields associated with it. The shapes in the layer inherit these attributes and may have their own values for each attribute field. An attribute field can store information of the following data types: integers, floats, doubles, strings, and integer lists.
The option menu contains a list of all attribute fields in the layer. From this option menu, one attribute field may be selected for display. The text field below it shows the value of the field for the current shape. This value can be modified in the text field. If there is more than one shape selected in the layer, this text field can be modified and the changes will apply to all of the selected shapes. A confirmation is always requested before any changes are actually made.
The "Attributes..." button at the bottom of the panel launches the Attribute Editor. The "Style..." button launches the Vector Style Editor. The "Query..." button launches the Attribute Query panel.
See Also: Vector Info