As discussed, it takes a lot of points to capture several acres of land effectively. To make things even more challenging, field crews often use abbreviated versions of descriptions to represent points, such as EP for edge of pavement, CLRD for centerline of road, and so on. The result is hundreds or even thousands of points all clumped together and labeled with cryptic abbreviated descriptions.Description keys solve this problem by automatically sorting the points onto the appropriate layers, rewriting the abbreviated descriptions to full-length descriptions, and automatically applying point styles to control the appearance of the points. For example, a description key will take a point coded as PP, place it on the utility layer, display it as a power pole, and rewrite the description to say POWER POLE. Imagine the time saved when this is done automatically for 10,000 points.
To use a description key to apply this type of automation to the tree points in your drawing, follow these steps:
- Open the drawing named Description Keys.dwg or (Description Keys.dwg (METRIC)) located in the Exercise_03 class data folder.
- Click the Settings tab of the Toolspace, and expand Point ➢ Description Key Sets.
- Right-click Essentials, and select Edit Keys.
- Click the style cell for code TR* to open the Point Style dialog box.
- Select Tree as the point style and click OK.
- Click the green check mark to dismiss Panorama.
- Click the Prospector tab, and then click Points.
- In the listing of points at the bottom of Prospector, scroll to the right and click the Raw Description column heading to sort the points by that property.
Tips :A raw description is usually the code that is entered in the field, and it is often abbreviated to save time and make it easier on field crews under potentially harsh conditions.
- Scroll to the bottom of the list where all of the TR points are now located.
- Right-click one of the points, and select Apply Description Keys. One of the points in the drawing should become a tree symbol.
- Select all of the TR points, and use the Apply Description Keys command to change them. All of the trees in the drawing are now clearly visible and appropriately represented.
- Return to the Settings tab, and edit the Essentials description key set once again. This time, assign a point label style of Description Only to the TR* code. Apply description keys to the TR points from within Prospector as you did before. The trees in the drawing are now labeled, although the label is the actual field code. A better result would be a more “polished” description.
- Edit the TR* description key code once again, this time changing the Format value to $1g $2 ($1mm $2). Apply the description keys to the TR points once again. This time, the labels make more sense and read 12g (300mm) PINE, 15g (375mm) MAPLE, and so on.
What’s Up with the Dollar Signs?
In the previous step, you used a code of $1" $2 to create the full description for the trees. The $ is a special code that tells Civil 3D that you want to use part of the raw description in the full description. The parts of the raw description are separated by spaces and numbered from left to right, starting at zero. Thus in the raw description TR 12 OAK, the TR is $0, 12 is $1, and OAK is $2. So $1" $2 becomes 12" OAK. With metric values in the raw description TR 300 OAK, the TR is $0, 300 is $1, and OAK is $2. So $1mm $2 becomes 300mm OAK. This is a great way for the person in the field to control the outcome in the drawing with as few keystrokes as possible.