Description Key Sets and Point Styles (CAD Clinic: Civil 3D Tutorial)

31 Mar, 2008 By: Phillip Zimmerman

A point style defines its name, its marker, its 3D geometry, and layers and their properties.

In the continuing discussion of styles, points are the first stop in an in-depth look at styles. Point styles are simple, but their use in any one project can be complex. With the emergence of GIS, point observations have become more than mere point number, elevation, and description. Sometimes additional attributes need identification along with a point's coordinates. These attributes can be collected as parameters or user-defined attributes. Points are also a project's bookends; they describe the existing conditions and define the future location of important design elements.

Point Styles
Civil 3D uses point styles to represent observed existing feature coordinates or critical design points. Whether the point styles represent observed or design coordinates, their coding should be consistent from project to project. Consistent names make the assignment of styles and creation of point groups a simple decision-making process.

A point's field description is known as a code or raw description. This code tends to be shorthand for a longer description, such as UP for utility pole, C 6 for coniferous tree with a 6" diameter, and so on. The longer description is known as a full description. The full description appears in a drawing.

A point style defines its name, what marker to display, its size, its 3D geometry behavior, and what layers it uses. The point style name is set in the point style's Information panel. Marker This panel in the point style dialog box defines the marker's display, size, and orientation. A marker can be an AutoCAD node, in which case the system variables PDMODE (point display mode) and PDSIZE (point display size) affect its display.

If the marker is a custom marker, it is under the control of Civil 3D settings. A custom marker replicates the PDMODE display shapes and can be one of the following: a node, a plus sign, an X, a short vertical line segment, or nothing. In addition to the basic shape, a marker can add a circle or a square.

Many times a marker denotes more than an observation; it can be a tree, a traffic signal, a sign, etc. In this case a simple marker is not enough; we need a symbol at the coordinates. The marker panel's lower right displays and identifies the symbol. All symbols must be in the drawing (template) as block definitions. The block viewer lists all of the drawing's blocks, and when you select a definition, the viewer displays it along with a label at the panel's right side.

Click for larger image The Marker tab in the Point Style - Basic dialog box. (Click image for larger version)

After identifying the marker shape you must size and define its orientation. The focus then shifts to the panel's upper right.

When determining a marker's size, you have four possible choices: drawing scale, fixed scale, absolute units, and size relative to the screen. The default sizing method is drawing scale. All sizing methods use the marker's size value.

Drawing scale determines the marker size by multiplying the symbol size by the viewport plotting scale. For the Benchmark point style, the symbol size would be 4 feet when the plotting scale is 1" = 40'. This size changes when the viewport plot scale changes (model or layout).

When you use the fixed-scale option, the fixed-scale area becomes active and you set the x, y, and z scaling factors.

When absolute units are used, the symbol does not need scaling; it remains the same size no matter the plotting scale. An example of this style is a tree canopy or a manhole grate. A tree canopy study plots as absolute units the size of a tree's canopy. Regardless of the plotting scale, its size does not change. The same goes for a manhole grate. If it is critical that the grate always shows its actual measurements, it is drawn in at actual size and is not scaled.

The last method automatically scales the symbols as a percentage of the display's vertical height. If set, the size value to the right changes to a percentage. When zooming in or out, the points resize by multiplying the display height by the percent. For example, if the percentage is 3 and the display height is 100, the marker size is 3 units. If the display height is 1000, the marker size is 30.

A marker's orientation is a result of its rotation angle and its orientation reference. The rotation angle rotates the marker regardless of its orientation reference. For example, setting the rotation angle to 45 rotates the marker counterclockwise 45 degrees.

Orientation reference (the second setting) has three possible values: Object, View, and World Coordinate System (WCS). When set to WCS, the marker's rotation is relative to WCS's zero direction even if the view is rotated. When orientation is set to Object, the marker rotates relative to its attached object. For example, placing markers on an alignment, the markers rotate in the direction of the alignment. When orientation is set to View, the markers rotate horizontally in a view.

3D Geometry
The 3D Geometry setting affects the elevations produced when a point is referenced. The three possible settings are Use Point Elevation, Exaggerate Points by Scale Factor, and Flatten Points to Elevation. When set to Use Point Elevation, referencing the point creates an object with the point's elevation.

When setting the value to Exaggerate Points by Scale Factor, referencing the point creates an object with an exaggerate elevation. For example, if the point's original elevation is 375 and the scale value is 2, the results will be an object with an elevation of 750.

When a value is set to Flatten Points to Elevation, the flatten elevation is assigned to the resulting object. This is only if the reference is with an AutoCAD object snap. For example, a point's elevation is 375 and flatten to elevation is set to 0 (zero). If drawing a line selecting the point object with an AutoCAD node object snap results in a line with an elevation of 0 (zero). If referencing the point with a point filter (point number or point object), the elevation of the resulting object is the point's elevation (375).

Click for larger image The 3D Geometry tab in the Point Style - Basic dialog box. (Click image for larger version)

The Display panel sets the layers for a point style's components and its view direction. A point style has two components (marker and a label) and two view directions (2D and 3D).

The point style assigns a layer for each component. The style can override any of the layer's properties (color, linetype, line type scale, or line weight). If you want the Layer Properties Manager to control these values, they should all be set to Bylayer. When you place a point and assign a label, the marker displays on the marker layer and the label on the label layer. If you want the same layers for the 3D view, you must assign the layers with view direction set to 3D.

To change the assigned layer, click the layer name and the Select Layer dialog box will display the current drawing's layer list. If the layer does not exist, the New button at Select Layer's top right creates a new layer in the drawing. If other drawings are open, you can select layers from those drawing by selecting them from the Layer Source dropdown list.

Click for larger image The Display panel of the Point Style - Basic dialog box. (Click image for larger version)

Now you know the basics of the point style and its settings. A point style defines its name, its marker, its 3D geometry, and layers and their properties. Next time I will review point label styles and their properties.

About the Author: Phillip Zimmerman

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