To continue this tutorial, go to Exercise 4: Smoothing a Surface.
4.4.4 Exercise 4: Smoothing a Surface
In this exercise, you will smooth a surface using the Natural Neighbor Interpolation (NNI) method.
For more information, see the AutoCAD Civil 3D Help topic Smoothing Surfaces. This exercise continues from Exercise 3: Adding a Hide Boundary.
Smooth a surface using NNI
1. Open Surface-4D.dwg, which is located in the tutorials drawings folder .
2. In Toolspace, on the Prospector tab, expand the XGND surface Definition collection and right-click Edits.
3. Click Smooth Surface.
4. In the Smooth Surface dialog box, specify the following parameters:
Select Method: Natural Neighbor Interpolation
Output Locations: Grid Based
The Grid Based output location interpolates surface points on a grid defined within specified polygon areas selected in the drawing. After the areas are defined, you can specify the grid X and Y spacing and orientation properties.
5. For the Select Output Region parameter, click the Value column. Click .
6. On the command line, enter Surface for the output region. This option will smooth the whole surface, rather than just the area within a specified rectangle or polygon.
7. In the Smooth Surface dialog box, specify the following parameters:
Grid X-Spacing: 10
Grid Y-Spacing: 10
8. In the drawing window, notice where some of the contour lines are especially angular. Click OK to smooth the surface.
The display of the surface is smoothed; contours are less angular. A Smooth Surface item is added to the Edits list view on the Prospector tab.
Note
The Description column in the list view displays the type of surface smoothing that was used (Natural Neighbor
Smoothing). You can delete theSmooth Surface edit from the list, but this does not reverse the smoothing operation until you rebuild the surface. You can also reverse the smoothing operation by using the U (undo) command.
To continue to the next tutorial, go to Creating a Watershed and Water Drop Analysis.
4.5 Tutorial: Creating a Watershed and Water Drop Analysis
This tutorial demonstrates how to create two kinds of surface analysis: watershed and water drop.
You use watershed analysis, which is one of several types of analysis that you can perform on a surface, to visualize and analyze the surface watersheds. You use water drop analysis, which is a separate utility, to trace the path that water would take across a surface. This tutorial includes the following general steps:
Configuring the watershed display and legend settings.
Configuring and creating a watershed analysis.
Inserting the watershed legend table.
Extracting objects from a surface.
Configuring and creating a water drop analysis.
Creating a catchment area.
AutoCAD Civil 3D uses the surface TIN lines to calculate the areas that water would flow along the surface. From these areas, the drain targets and watersheds are determined.
Other types of surface analysis include slope, aspect, elevations, and contours.
For more information, see the AutoCAD Civil 3D Help topics Watersheds and Analyzing Surfaces.
Topics in this section
Exercise 1: Configuring a Style for Watershed Display
In this exercise, you will configure a style for watershed display.
Exercise 2: Generating a Watershed Analysis
In this exercise, you will generate and display the watershed analysis.
Exercise 3: Creating a Watershed Legend
In this exercise, you will add a watershed legend table to the drawing.
Exercise 4: Extracting Objects from a Surface
In this exercise, you will use the watershed data to create non-destructive AutoCAD objects from the surface.
Exercise 5: Analyzing Surface Water Runoff
In this exercise, you will create lines that illustrate the path that flowing water would take across a surface.
Then, you will create a polygon that defines the catchment region and its area on the surface.
4.5.1 Exercise 1: Configuring a Style for Watershed Display
In this exercise, you will configure a style for watershed display.
For more information, see the AutoCAD Civil 3D Help topic Surface Styles and Visualization. Configure a style for watershed display
1. Open Surface-5A.dwg, which is located in the tutorials drawings folder .
2. In Toolspace, on the Settings tab, expand the Surface Surface Styles. Right-click the Standard surface style.
Click Copy.
3. In the Surface Style dialog box, on the Information tab, for Name, enter Watersheds.
4. On the Watersheds tab, in the Watershed Properties table, expand the Depression Watershed property group.
Change Use Hatching to True.
5. Click Hatch Pattern and click .
6. In the Hatch Properties dialog box, specify the following parameters:
Pattern: AR-SAND
Scale: 15 7. Click OK.
8. On the Display tab, in the Component Display table, click next to Watersheds to turn on display of the watershed components.
9. Click OK.
To continue this tutorial, go to Exercise 2: Generating a Watershed Analysis.
4.5.2 Exercise 2: Generating a Watershed Analysis
In this exercise, you will generate and display the watershed analysis.
For more information, see the AutoCAD Civil 3D Help topic Analyzing Surfaces. This exercise continues from Exercise 1: Configuring a Style for Watershed Display. Generate a watershed analysis
Note
This exercise uses Surface-5A.dwg with the modifications you made in the previous exercise.
1. In Toolspace, on the Prospector tab, expand the Surfaces collection. Right-click the XGND surface. Click Surface Properties.
2. In the Surface Properties dialog box, on the Information tab, for Surface Style, select Watersheds.
3. On the Analysis tab, for Analysis Type, select Watersheds.
4. Ensure that Standard is selected in the Legend list.
5. Click to generate the watershed analysis.
The details of the surface watersheds are displayed in the Details table.
6. Click .
7. On the Watershed Display dialog box, click next to Boundary Point and Boundary Segment to turn off the display of these watershed types.
8. Click OK twice.
The watersheds are displayed on the surface in the drawing.
9. In Toolspace, on the Prospector tab, expand the Surfaces XGND collection. Click the Watersheds collection.
The Prospector list view displays a tabular list of the surface watersheds with their IDs, description, type, and the ID of the watershed that they drain into.
10. Optionally, pan or zoom to an individual watershed. Right-click the watershed item in the list view and click Pan To or Zoom To.
To continue this tutorial, go to Exercise 3: Creating a Watershed Legend.
4.5.3 Exercise 3: Creating a Watershed Legend
In this exercise, you will add a watershed legend table to the drawing.
For more information, see the AutoCAD Civil 3D Help topic Adding Surface Legend Tables. This exercise continues from Exercise 2: Generating a Watershed Analysis.
Create a watershed legend table Note
This exercise uses 5A.dwg with the modifications you made in the previous exercise, or you can open Surface-5B.dwg from the tutorials drawings folder .
1. In Toolspace, on the Settings tab, expand the Surface Table Styles Watershed collection.
2. Right-click the Standard style. Click Edit.
3. In the Table Style dialog box, on the Data Properties tab, clear the Sort Data check box.
4. Click OK.
5. Click Annotate tab Labels & Tables panel Add Tables menu Add Surface Legend Table.
6. At the prompt to specify the table type, enter Watersheds.
7. You are prompted to specify whether you want the table to automatically update if the analysis information changes.
Enter Dynamic to enable automatic updating.
If a change is made to the surface and the watershed analysis is regenerated, the legend is automatically updated.
8. Click a location in the drawing where you want to place the upper-left corner of the table.
The legend table is displayed in the drawing at the selected location.
To continue this tutorial, go to Exercise 4: Extracting Objects from a Surface.
4.5.4 Exercise 4: Extracting Objects from a Surface
In this exercise, you will use the watershed data to create non-destructive AutoCAD objects from the surface.
For more information, see the AutoCAD Civil 3D Help topic Extracting Surface Data. This exercise continues from Exercise 3: Creating a Watershed Legend.
Extract objects from a surface Note
This exercise uses Surface-5B.dwg with the modifications you made in the previous exercise.
1. In the drawing, select the surface.
2. Click TIN Surface tab Surface Tools panel Extract Objects .
3. The Extract Objects From Surface dialog box lists all of the surface properties that are visible in the currently selected surface style. Clear all boxes in the Properties column except for Watersheds.
4. Click OK.
AutoCAD objects are created from each of the watersheds in the drawing.
5. In the drawing, click inside a watershed area.
6. On the command line, enter List.
The AutoCAD text window displays parameters for the object you selected.
You can use any of the standard AutoCAD commands to modify or query the new object.
To continue this tutorial, go to Exercise 5: Creating a Water Drop Analysis.
4.5.5 Exercise 5: Analyzing Surface Water Runoff
In this exercise, you will create lines that illustrate the path that flowing water would take across a surface. Then, you will create a polygon that defines the catchment region and its area on the surface.
The water drop utility creates either a 2D or 3D polyline object that runs downhill on a surface from any point you select. You can specify whether the point you select is indicated with a marker. After the lines are created, you can edit or modify them as needed.
You can use the information you get from the water drop analysis to calculate catchment areas, based on specified low points of the surface. The catchment regions can be created on the surface as either 2D or 3D polygons, which can be exported to a hydrology application for detailed analysis.
For more information, see the AutoCAD Civil 3D Help topics Drawing Water Drop Paths and Displaying and Calculating Catchment Areas.
This exercise uses a drawing file similar to the one used in Exercise 3: Creating a Watershed Legend. The surface style is changed to make it easier to see the basic surface features, and it contains a simple point style for you to use as a start point marker.
This exercise continues from Exercise 4: Extracting Objects from a Surface. Perform a water drop analysis
1. Open Surface-5C.dwg, which is located in the tutorials drawings folder .
2. Click Analyze tab Ground Data panel Flow Paths drop-down Water Drop . 3. In the Water Drop dialog box, specify the following parameters.
Path Layer: C-TOPO-WDRP
Path Object Type: 2D Polyline
Place Marker At Start Point: Yes
Start Point Marker Style: WD Start 4. Click OK.
5. In the drawing, click several locations near those displayed in the following illustration.
A 2D polyline is drawn, representing the flow of water from the spot you selected. The start point of the path is indicated by a marker.
If a water path splits, additional lines are drawn to follow each path.
Waterdrop paths (arrows indicate culvert inlet locations)
6. Press Enter to end the waterdrop command.
Notice that most waterdrop paths in this area drain to the culverts that are indicated by the red arrows. Next, you will use the water drop paths you just created to define a catchment area that influences the culverts.
Create catchment areas
1. Click Analyze tab Ground Data panel Catchments drop-down Catchment Area . 2. In the Catchment dialog box, specify the following parameters:
Display Discharge Point: Yes
Discharge Point: Catchment
Catchment Layer: C-TOPO-CATCH
Catchment Object Type: 2D Polyline 3. Click OK.
4. In the drawing, click the marker for each waterdrop path.
Blue polygons that define each catchment region are created. The area value of each catchment region is displayed on the command line. In the drawing, each catchment point is indicated by a marker.
Note
If you receive a message indicating that the specified location results in a catchment area with no area, it means that there is no flat area or high spot on the specified point.
5. Press Enter to end the catchment area command.
Catchment areas defined
Combine multiple catchment areas
1. In the drawing, select the polygons that define catchment areas. Right-click. Select Isolate Objects Isolate Selected Objects.
The polygons are displayed in the drawing window, but all other objects are hidden.
2. Select the polygons again.
3. On the command line, enter LineWorkShrinkWrap.
A black polygon that contains the combined area of the catchment areas is displayed. The LineWorkShrinkWrap command creates a single outside boundary of a selection of touching polygons. The original polygons are not deleted.
Combined catchment areas
4. In the drawing, right-click. Click Isolate Objects End Object Isolation.
The remaining drawing objects are displayed in the drawing window.
Tip
You can transfer individual or shrinkwrapped catchment area polygons to a hydrology application for further analysis.
To continue to the next tutorial, go to Generating Surface Volume Information.