Adding Breaklines to a Surface

Breaklines are used to define surface features and to force triangulation along the breakline. Surfaces do not triangulate across breaklines, creating more accurate TIN surface models.

In this exercise, you will create breaklines along the edge of pavement for an existing road. Breaking the surface along features produces a more accurate surface rendering

This exercise continues from Exercise 2: Adding Point Data to a Surface.

Display the source polylines and change the surface style

Note:
This exercise uses the drawing you created in the previous exercises, or you can open Surface-1B.dwg from the tutorials drawings folder.
1. Click Home tab Layers panel Layer drop-down. Next to the _EG_BREAKLINES layer, click .
   The 3D polylines that represent the edge of pavement (EP) of an existing road are displayed on the east side of the site.
   Note:

   The EP polylines were included in the drawing template you used in Exercise 1: Creating a TIN Surface.
2. Select the surface. Right-click. Click Surface Properties.
3. In the Surface Properties dialog box, on the Information tab, for Surface Style, select Contours and Triangles. Click OK.
   The surface now shows contours and triangles that illustrate the EG surface triangulation.
1. Create breaklines from the polylines
2. In Toolspace, on the Prospector tab, expand the SurfacesEGDefinition collections. Right-click Breaklines. Click Add.
3. In the Add Breaklines dialog box, for Description, enter Edge of pavement - existing road. Use the default values for the other fields. Click OK.
4. The Select Objects prompt becomes active. While in this command, use the Zoom and Pan commands to locate the two blue 3D polylines on the east side of the site.
   Zoom in close so you can see that the triangles cross over the polylines

Select the polylines. Press Enter.

The surface triangulation is modified. The edge of pavement breaklines are applied, and the TIN surface is adjusted along the breakline edges, modifying the surface triangulation.

1. Click View tab Navigate 2D panel Extents.
   The drawing window zooms to the extents of the surface. With the breakline data added, the layer that contained the source data for the breaklines can be frozen.
2. Click Home tab Layers panel Layer drop-down. Next to the EG_BREAKLINES layer, click .

Further exploration: Notice that, along some portions of the polylines, the surface triangulation incorrectly crosses the breakline. This happened because the surface contours also act as breaklines. The new breaklines are not added because the contours are already acting as breaklines, and the current surface setting does not allow more than one breakline to affect the surface at a given point. To override this behavior, you can perform any of the following tasks:

• Build the surface with contours and breaklines: In the Surface Properties dialog box, on the Definition tab, expand the Build collection. Set Allow Crossing Breaklines to Yes, and then set Elevation to Use to Use Last Breakline Elevation at Intersection.
• Modify the surface: Use the DeleteSurfacePoint command to delete surface points that are located exactly on the polylines.
• Modify the polylines: Add a vertex to the polylines at each location where it crosses a surface contour.

Adding Point Data to a Surface

Import point data into the current drawing

1. Open drawing Surface-1A.dwg , which is available in the tutorials drawings folder.
   This drawing contains an empty surface definition, which is named EG.
2. Click Modify tab Ground Data panel Surface  Find.
3. Click Surface tab Modify panel Add DataPoint Files  Find.

1. Under Selected Files, click .
2. In the Select Source File dialog box, browse to the tutorial folder. Select Surface-1A-PENZD (space delimited).txt. Click Open.
3. In the Add Point File dialog box, under Specify Point File Format, select PENZD (Space Delimited).
4. In the Add Point File dialog box, click OK.
5. At the command line, enter ZE.
   The surface, which contains the imported point data, is displayed in the drawing.

Creating a TIN Surface

Create a TIN surface in a new drawing

1. Click New.
2. In the Select Template dialog box, browse to the tutorial folder. Select Surface.dwt. Click Open.
3. Click Home tab Create Ground Data panel Surfaces drop-down Create Surface  Find.
4. In the Create Surface dialog box, for Type, select TIN surface .
   Note:

   By default, a new Surface Layer will be created named C-TOPO- followed by the name you enter in the Name cell. You can also click  to specify an existing layer for the surface.
5. In the Properties table, specify the following parameters:
   • Name: EG
   • Description: Existing Ground surface from imported point data
   • Style: Points and Border
     Tip:

     To select the style, click the Value cell, and then click  to display the Select Surface Style dialog box.
   • Render Material: ByLayer
6. Click OK.
7. In Toolspace, on the Prospector tab, expand the Surfaces collection.
   The new surface name is displayed in the Surfaces collection in Toolspace on the Prospector tab, but this surface does not contain any data.

Viewing Data in a Database Table

When you have configured a data source, you can use the Data View window to view database records from within the program.

Once you have configured a data source, you can access its database tables from within the program. The Data View is a window where you can view and edit database records. Database tables can be opened as read-only or for editing. You cannot add, delete, or edit records in a database table that you open in Read-only mode. Opening a database table establishes a connection to its parent database. Some database systems require that you enter a valid user name and password before you can connect to them.

The Data View window is a spreadsheet-like environment that presents a database table's records. With the scroll bars and navigation buttons at the right and at the bottom of the window, you can move through the record set.

The grid in the Data View window contains the following elements:

• Column header. Selects all records in a column when you click it.
• Record header. Selects an individual record when you click it.
• Grid cells. Selects one field of a given record when you click it.
• Grid header. Selects the entire database table.

The Data View window provides a great deal of flexibility in how records are displayed. You can

• Move or resize columns
• Hide columns to remove them from the Data View window display
• Sort column data in ascending or descending order
• Freeze a column or combination of columns so that they stay in place and do not scroll with the horizontal scroll bar
• Align text within individual columns
• Apply a variety of font styles and sizes to the Data View window display

Column formatting and database table sorts in the Data View window are not stored. This information is discarded when you open a new database table or close the current table. If you want to create and save a formatted report, you must copy the contents of the Data View window to the Clipboard and paste it into an external program such as Microsoft Excel. You can then use the external program to apply and save the desired formatting. For details about creating a template, refer to the documentation of the external program that you are using to format the data.

Database Views and External Queries

Some database management systems support views. Views provide additional ways to display data from a database table. For example, you can use a view to display a subset of the overall database table. You can also use views to define relationships between database tables and create a new table that contains combined records from the original database tables.

Database systems that do not support views can produce similar results with queries. Refer to your database system documentation for information about creating and working with views and queries.

Views and external queries are displayed in the Data Sources node of the dbConnect Manager. External queries are queries created and stored outside of the program but within an external database system. You can work with external queries and views as you would work with any other database table. You can view or edit them in the Data View window, construct queries based on them, and create links and labels based on their records.

Using the Data Extraction Wizard

You use the Data Extraction wizard to choose the data source (drawings) to extract property data from selected objects. You can output the data to a table or external file.

The Data Extraction wizard guides you through the process of

• Selecting the data source, which can be a drawing, set of drawings, or folders.
• Filtering objects (non-blocks and blocks) are extracted and selecting properties from which data is extracted.
• Organizing and refining the extracted data.
• Merging information from an Excel spreadsheet with the extracted data.
• Choosing an output format for the data (a table and/or an external file).
• Formatting the extracted data in a table by specifying a table style or selecting an existing pre-formatted table.

The first time you extract data, you are prompted to save the data extraction settings in a data extraction (DXE) file. Later, if you need to edit the data extraction, you select the DXE file, which contains all the settings (data source, selected objects and their properties, output format and table style) that you used to create the extraction.

 

For example, if you wanted to remove some property data from the extraction, you would select the DXE file that was used to create the extraction and made the desired changes.

A data extraction file can also be used as a template to perform the same type of extraction in a different drawing. 

           The DXE file stores drawing and folder selections, object and property selections, and            formatting choices. If you need to extract the same type of information repeatedly, using a DXE file is time-saving and convenient.

• You can also edit a DXE file. You can add or remove drawings, add or remove objects, or select different properties from which to extract data. Tables that reference the same DXE file, even if those tables are in other drawings, display the changes when those tables are updated.
  Note: You can use an attribute extraction (BLK) file as a template for extracting data from blocks and attributes. When using a BLK file for extracting data or editing an existing extraction, you are prompted to save the data extraction to a DXE file in order to proceed with the extraction.

Changing Data Extraction Table Formatting

You can modify a data extraction table by changing the formatting, adding columns and rows, or editing data in the cells.

Once a data extraction table is inserted into the drawing, you can make formatting changes, add columns and rows, and edit cells containing extracted data.

Any formatting, structural, or data changes that are made are retained after the table is updated. For example, if you added shading to a header row, or the formatting of text in certain columns changed, those changes are not lost when the table is updated.

By default, all cells in a data extraction table are locked for editing and unlocked for formatting changes. You can unlock or lock cells for data and formatting edits by accessing the table’s shortcut menu.

Add Columns and Rows

You can add columns and rows to a data extraction table without affecting the extracted data. When you select a table, the lines around cells that contain extracted data is bold. Columns and rows can only be added outside this perimeter. You should be aware that blank cells may be created as a result if additional data is extracted during an update, or conversely, there are fewer columns or rows containing extracted data.

For example, if you added a row and column to a table after you inserted into the drawing, the area populated with extracted data will be expanded by an additional column after the table is updated. The column and row that you manually added are still part of the table, but a blank cell is created where a void exists in the table.

Using the same example, if the table was updated and the number of columns and rows containing extracted data were reduced, the columns and rows you inserted would remain in the same place. The area that originally contained data extraction columns and rows is now replaced with blank cells.

Edit Cell Content

Data cells are locked by default in order to prevent unintentional changes. You can manually unlock a cell to edit its contents. When the table updates, you are given a choice to overwrite the edited cells or choose to have the update not update the cells.

Parametric Drawing and Constraints

Parametric drawing is a technology that is used for designing with constraints, which are associations and restrictions applied to 2D geometry.

There are two general types of constraints:

• Geometric constraints control the relationships of objects with respect to each other
• Dimensional constraints control the distance, length, angle, and radius values of objects

The following illustration displays geometric and dimensional constraints using the default format and visibility.

A cursor badge displays when you move the cursor over an object that has constraints applied to it.

In the design phase of a project, constraints provide a way to enforce requirements when experimenting with different designs or when making changes. Changes made to objects can adjust other objects automatically, and restrict changes to distance and angle values.

With constraints, you can

• Maintain design specifications and requirements by constraining the geometry within a drawing
• Apply multiple geometric constraints to objects instantly
• Include formulas and equations within dimensional constraints
• Make design changes quickly by changing the value of a variable

Best practice: It is recommended that you first apply geometric constraints to determine the shape of a design, and then apply dimensional constraints to determine the size of objects in a design.

Designing with Constraints

When you work with constraints, a drawing will be in one of three states:

• Unconstrained. No constraints are applied to any geometry.
• Underconstrained. Some constraints are applied to the geometry.
• Fully constrained. All relevant geometric and dimensional constraints are applied to the geometry. A fully constrained set of objects also needs to include at least one Fix constraint to lock the location of the geometry.

Thus, there are two general methods for designing with constraints:

• You can work in an underconstrained drawing and make changes as you go, using a combination of editing commands, grips, and adding or changing constraints.
• You can create and fully constrain a drawing first, and then control the design exclusively by relaxing and replacing geometric constraints, and changing the values in dimensional constraints.

The method that you choose depends on your design practices and the requirements of your discipline.

Note: The program prevents you from applying any constraints that result in an overconstrained condition.

Remove or Relax Constraints

There are two ways to cancel the effects of constraints when you need to make design changes:

• Delete the constraints individually and later apply new constraints. While the cursor hovers over a geometric constraint icon, you can use the Delete key or the shortcut menu to delete the constraint.
• Relax the constraints temporarily on selected objects to make the changes. With a grip selected or when you specify options during an editing command, tap the Shift key to alternate between relaxing constraints and maintaining constraints.

Relaxed constraints are not maintained during editing. Constraints are restored automatically if possible when the editing process is complete. Constraints that are no longer valid are removed.

Change true ellipse into polyline

Issue:

You want to convert a true ellipse to a polyline ellipse.

Solution:

Solution

Use the following procedure to create a polyline ellipse in a new blank drawing. If you already have a drawing with true ellipses, begin at step 3.

1. Set the PELLIPSE (System Variable) to 0 (to draw true ellipses)
2. Draw an ellipse on the screen.

3. Set the PELLIPSE system variable to 1 (to draw polyline ellipses).
4. Set the PLINETYPE (System Variable) to 0 (polylines will not be altered when they are placed into the drawing)
5. From the Quick Access Toolbar select "Saveas..." or enter dxfout on the command line.
6. From the Save As dialog, Files of type: drop-down list, select AutoCAD R12/LT2DXF(*.dxf)

7. From the top-right of the Save As dialog, select Tools - Options

8. Click the DXF Options tab.
9. Select the Select Objects option 
10. Click OK, and then click Save.
11. Select the ellipse(s), and press ENTER to save the DXF.
12. Enter ERASE on the command line .
13. Select the ellipse(s), and press ENTER to erase it.
14. Enter INSERT on the command line, and select the DXF file.
15. Clear the Specify On-screen to Insert the Block at 0,0 option, select the Explode option, and then click OK.
16. Select the Ellipse and view the properties in the Properties palette. It is now listed as a polyline.