AutoCAD Civil 3D Tutorials

How to import a point cloud into a drawing and create a surface model?

noreply@blogger.com (CAD Civil 3D) — Tue, 11 Oct 2022 18:00:00 +0000

As laser scan data collection becomes more common and replaces other large-scale data-collection methods, the ability to use point clouds in Civil 3D is critical. Intensity helps postprocessing software determine the ground cover type. While Civil 3D can’t do postprocessing, you can see the intensity as part of the point cloud style.

Import an LAS format point cloud file0422_Exercise_Denver.las into the Civil 3D template of your choice. As you create the point cloud file, set the style to Elevation Ranges. Use a portion of the file to create a Civil 3D surface model. No coordinate system needs to be set for this example.

Solution

Start a new file by using the default Civil 3D template of your choice. Save the filebefore proceeding as 0422_Exercise_DenverUSA.dwg.
In Prospector, right-click Point Clouds and select the Create Point Cloud option to display the Create Point Cloud Wizard.
Set the name of the point cloud to Denver.
Set the point cloud style to Elevation Ranges, and click the Next button.
Use the white plus sign to browse to the LAS file.
Select 0422_Exercise_Denver.las and select click Open. Click Finish. The New Point Cloud Processing In Background dialog will open. Click Close to dismiss.
This file contains 4.7 million data points, so be patient while the file imports.
When the point cloud has completed processing, zoom extents. Select the bounding box representing the point cloud to display the Point Cloud contextual tab.
Select the Add Points To Surface command.
Name the surface, set a surface style, and click the Next button.
Choose the Window radio button and click Define Region In Drawing.
Define the region by creating a window around the western half of the point cloud.
Click Next to see the Summary page and click the Finish button. Close Panorama.

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Label surface contours and spot elevations

noreply@blogger.com (CAD Civil 3D) — Mon, 10 Oct 2022 18:00:00 +0000

Showing a stack of contours is useless without context. Using the automated labeling tools in Civil 3D, you can create dynamic labels that update and reflect changes to your surface as your design evolves.

Open the0421_Exercise.dwg or (0421_Exercise_METRIC.dwg) file.
Label the major contours on the surface at 2' and 10' (Background) or 1 m and 5 m (Background).

Solution

Select the surface. From the TIN Surface contextual tab ➢ Modify panel, click the Surface Properties icon.
On the Information tab, change the style to Contours 2' and 10' (Background) or Contours 1 m and 5 m (Background).
Click OK to close the dialog and press Esc to deselect.
From the Annotate tab ➢ Labels & Tables panel, click the Add Labels button.
Set Feature to Surface and Label Type to Contour – Multiple.
Set Major Contour Label Style to Existing Major Labels and Minor Contour Label Styleto <none>.
Click Add.
Pick a point on one side of the site and draw a contour label line across the entire site. Press Esc to exit the command.

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Prepare a slope analysis

noreply@blogger.com (CAD Civil 3D) — Thu, 06 Oct 2022 18:00:00 +0000

Surface analysis tools allow users to view more than contours and triangles in Civil 3D. Engineers working with nontechnical team members can create strong, meaningful, analysis displays to convey important site information using the built-in analysis methods in Civil 3D.

Open the0420_Exercise.dwg or (0420_Exercise_METRIC.dwg) file.
Create a slope banding analysis showing slopes under and over 10 percent and insert a dynamic slope legend to help clarify the result of the analysis.

Solution

Select the surface. From the TIN Surface contextual tab ➢ Modify panel, click the Surface Properties icon.
On the Information tab, set the Surface Style field to Slope Banding (2D).
Switch to the Analysis tab for the Slopes analysis type.
Set Ranges Number to 2 and then click the Run Analysis arrow.
Change both the maximum slope for ID 1 and the minimum slope for ID 2 to 10 percent.
Click OK to close the Surface Properties dialog.
Select the surface to display the TIN Surface contextual tab.
From the TIN Surface contextual tab ➢ Labels & Tables panel, choose Add Legend Table.
Enter S ↲ and then D ↲ at the command line and pick a placement point on the screen to create a dynamic elevations legend.

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How to modify and update a TIN surface?

noreply@blogger.com (CAD Civil 3D) — Wed, 05 Oct 2022 18:00:00 +0000

TIN surface creation is mathematically precise, but sometimes the assumptions behind the equations leave something to be desired. By using the editing tools built into Civil 3D, you can create a more realistic surface model.

Continue working in the file from the previous exercise or open the0419_Exercise.dwg or (0419_Exercise_METRIC.dwg) file.
Use the irregular-shaped polyline and apply it to the surface as an outer boundary of the surface. Make the boundary a destructive breakline.

Solution

Expand the Surfaces ➢ Existing ➢ Definition branches.
Right-click Boundaries and select the Add option.
Verify that the check box by Non-Destructive Breakline is unchecked and click OK. Select the magenta-colored polyline to complete the boundary addition.

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How to create an existing ground surface using points?

noreply@blogger.com (CAD Civil 3D) — Tue, 04 Oct 2022 18:00:00 +0000

The most common way to create a surface model is by adding point data to the definition of a surface.

Open the0418_Exercise.dwg or (0418_Exercise_METRIC.dwg) file. Create a new surface called Existing. Add the point group Topo to its definition. Leave the default styles.

Solution

On the Home tab ➢ Create Ground data panel of the ribbon, click Surfaces ➢ Create Surface.
Name the surface Existing and click OK.
In Prospector, expand the Surfaces ➢ Existing ➢ Definition branches.
Right-click Point Groups and select Add.
Select the point group Topo and click OK.

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Working with Large Surfaces

noreply@blogger.com (CAD Civil 3D) — Thu, 18 Aug 2022 18:00:00 +0000

A surface has a limit to the number of points it can contain before caching its definition to an external file. The only way to prevent this is to reduce the amount of data in the surface definition. If this is not an option, the cache file will be created in the same folder where the drawing file has been saved. This file must remain in the folder with the drawing file for the surface definition to remain in the drawing. If the cache file is deleted, moved, or renamed, the surface will no longer appear in the Prospector or function in the drawing. What will remain in the drawing will be a proxy entity.

The cache file will bear the name of the drawing file along with its AutoCAD object handle ( <drawing_name>_<surface object handle> ). For grid surfaces, the limit for the number of points is about 1 million, and the file extension of the cache file will be .grs. For TIN surfaces, the limit is about 2 million, and the file extension of the cache file will be .mms. There are several options for working with large surfaces depending on the situation:

Data Clip Boundaries: As discussed earlier, a data clip boundary is a type of boundary that can be added before any elevation data is added. This is the best option to use if you have information covering a large geographic area but are working only in a smaller area.
Cropped Surface: The Create Cropped Surface command can be found in the contextual tab of your surface, hidden in the Surface Tools panel flyout. This command will break off a piece of a surface model and allow you to send the smaller piece to a new drawing. This is a fast way to create a new drawing containing the desired surface data. The major disadvantage to the cropped surface tool is that there is no connection between the original surface and its spawn. In other words, if the original surface is changed, the new surface will not be affected.
Data Shortcuts: The best of both worlds, data shortcuts allow you to work in a new file but remain connected to the surface’s source data. Another major advantage of using data shortcuts is that multiple users can access the surface data without duplicating it.

Here are some other hints that will be helpful in increasing performance when working with large surfaces:

Turn on the Level Of Detail option in the Views panel of the View tab.
Do not use the Rebuild-Automatic option.
Turn off the selection preview on the Selection tab of the Options dialog.
Clear the Show Tooltips option in the Surface Properties dialog.

Destructive vs. Non-destructive Boundaries

noreply@blogger.com (CAD Civil 3D) — Wed, 17 Aug 2022 18:00:00 +0000

The boundary types outer, show, and hide all have the option to be destructive (i.e., the Nondestructive Breakline check box is cleared) or non-destructive (i.e., the Non-destructive Breakline option is checked). What Civil 3D is “destroying” are the triangles that underlie the boundary.

The following image shows a schematic of a surface model before a boundary is added. For illustration purposes, triangle vertices have been highlighted with different shapes. The stars represent surface data points inside the boundary, and the circles represent points outside of the boundary.

Use the Non-destructive Breakline option when the data you are working with is valid right up to the boundary edge. A boundary added as a non-destructive breakline will retriangulate the surface and create triangles up to the boundary, as shown in the following image. The squares show locations where Civil 3D has interpolated a surface data point at the boundary. The portion of the surface that would be hidden by adding a boundary is being shown in light gray for illustration purposes.

Use a destructive boundary if the line you are adding as a boundary is an approximation of the area you want to rein in. A boundary added as destructive will remove any triangle lines it crosses. The following image shows the illustration surface with the same boundary as before but added as destructive. The portion of the surface that would be hidden by adding a boundary is being shown in gray for illustration purposes. Notice how the outermost triangle legs of the surface areall inside the boundary.

Consider a surface that needs an outer boundary, for example. If you create a rough polyline that encloses the points you want to include as your surface model, add the polyline to the surface as an outer boundary with the non-destructive option cleared.

If you deliberately created the polyline by snapping each vertex of the boundary to a surveyed point, for example, you could add it as a non-destructive breakline.

You will need to use your professional judgment to know when to use the Non-destructive Breakline option and when to use the Destructive Breakline option, but a good rule of thumb is that outer boundaries are usually destructive. Hide and show boundaries are usually non-destructive.

With the exception of data clip boundaries, you’ll want to have your boundaries among the last operations in your surface-building process. Therefore, as future edits are made, you may want to move the Add Boundary build operation back to the bottom of the Data Operations list on the Definition tab in the Surface Properties dialog, which will be discussed later in this blog.

Adding Boundaries

noreply@blogger.com (CAD Civil 3D) — Tue, 16 Aug 2022 18:00:00 +0000

Use boundaries when you want to restrict the area where triangles are being generated. Many object types can be used as surface boundaries, such as survey figures, feature lines, 2D polylines, and 3D polylines. Whatever type of line you choose as your boundary, it must be closed and cannot cross itself (i.e., no “loop-the-loops”). Elevations of the boundaries are ignored. There are four types of surface boundaries:

Outer: Outer boundaries are used to conceal surface components (triangles, contours, or points) occurring outside the boundary extents.
Hide: Hide boundaries are used to conceal surface components inside the boundary extents.
For example, consider a hide boundary to hide any interpolation occurring inside a building perimeter.
Show: Show boundaries are used to reveal surface components inside a hide boundary. If a hide boundary was used around a building perimeter, a show boundary can be applied to reveal contours in the building’s courtyard for landscape purposes. Show boundaries can also be used to show surface areas outside an outer boundary.
Data Clip: A data clip is a type of boundary drawn around the extents of a site. It is used to prevent surface calculations from occurring beyond its extents. The data clip boundary should be the first component added to the surface definition. For example, if a DEM file representing the surface of an entire county will be used to create a surface, a data clip boundary can be applied first to exclude the grid information outside the construction site. Using a data clip boundary will result in smaller surfaces (fewer surface points), which will impact your file size.

The addition of every boundary is considered a separate part of the building operations. This means that the order in which the boundaries are applied controls their final appearance. For example, a show boundary listed before a hide boundary created in the same area will be overridden by that hide operation.

One way to start defining more accurate boundaries is to first extract the boundary defining the extents of the surface to a polyline and then edit the polyline to the optimum shape. The Extract Objects From Surface utility allows you to re-create any displayed surface element (contours, border, and the like) as an independent AutoCAD entity. It is important to note that only the objects that are currently visible in the surface style can be extracted. In this exercise, you’ll extract the existing surface boundary as a starting point for creating a more refined boundary that will limit triangulation:In this example, you’ll add some breaklines that describe road and ditch features:

Open the 0403_SurfaceBoundary.dwg or (0403_SurfaceBoundary_METRIC.dwg) file.
Select the surface.

From the TIN Surface contextual tab ➢ Surface Tools panel, choose Extract From Surface ➢ Extract Objects to open the Extract Objects From Surface dialog.
Leave the Border object selected and deselect the Major Contour, Minor Contour, and Points options, as shown in Figure 1.
Figure 1: Extracting the border from the surface object.
Click OK to finish the process. Press Esc to deselect the surface.
A 3D polyline has been created from the surface border.
Pick the border 3D polyline.
This polyline will form the basis for your outer surface boundary. By extracting the border polyline from the existing surface, you save a lot of time playing connect the dots along the points that are valid. Next, you’ll add this polyline into the surface as a boundary.
In Prospector, expand the Surfaces ➢ Existing Surface ➢ Definition branches.
Right-click Boundaries and select the Add option.
The Add Boundaries dialog opens (see Figure 2).
Figure 2: Add Boundaries dialog.
Enter the name Outer, leave Type set to Outer, and keep the check mark next to the Nondestructive Breakline option; then click OK.
Pick the 3D polyline border that you previously extracted.
Working your way around the site clockwise, grip-edit the polyline you created in step 6 to exclude some of the area at the northwest area of the site around the ditch where there are no points. Use the Add Vertex option from the grip menu, as shown in Figure 3.
Figure 3: Using the grips to adjust the border.
Note that this process does not require you to use object snaps. This boundary only needs to be approximate. You will see the surface dynamically update with each grip edit since the surface is set to Rebuild Automatic.
If time permits, edit the entire boundary.
On a large site, you can see that this is a time-consuming process but worth the effort to clean up the site nicely (see Figure 4). Thankfully, there are other methods you can use to clean up the surface border; we will discuss these methods in later exercises.
Figure 4: A non-destructive outer boundary in action.
Save the drawing and keep it open for the next portion of the exercise.
Notice in some areas along the outer boundary how the edge of the triangulation includes points shown as a square with a + symbol; these are the additional points created along the boundary line where it intersects with the triangles it crosses. The points you attempted to exclude from the surface are still being included in the calculation of elevations for this point; they are just excluded from the display and calculations. This isn’t the result you were after, so let’s fix it now.
In Prospector, expand the Surfaces ➢ Existing Surface ➢ Definition branches and select Boundaries.
A listing of the boundaries appears in the preview area of Toolspace.
Right-click the boundary you just created and select the Delete option.
Click OK in the warning dialog that tells you the selected definition items will be permanentlyremoved from the surface.
You can dismiss Panorama if it appears.
In Prospector, right-click Boundaries and select the Add option again.
The Add Boundaries dialog appears.
Enter the name Outer, leave Type set to Outer, and leave the check box unchecked next to the Non-destructive Breakline option; then click OK.
Pick the revised 3D polyline again.
Notice that no triangles intersect your boundary now where it does not connect points, as shown in Figure 5.
Figure 5: A destructive outer boundary in action.
In Prospector, right-click Boundaries and select the Add option again.
Name the boundary Buildings and change Type to Hide. Make sure that Non-destructive
Breakline is checked, as shown in Figure 6, and click OK.
Figure 6: Adding buildings as nondestructive, hide boundaries.
Select the outer outline of the cyan building in the northwest portion of the site. Press Enter.
You should now have a void in your surface where the building exists.
Right-click Boundaries and select the Add option one last time.
Name the boundary Courtyard, set the type to Show, and verify that Non-destructive
Breakline is checked.
Click OK; then click the closed polyline inside the building outline and press Enter.
You should now see an island of surface data inside the previously hidden location.

When this exercise is complete, you can close the drawing. A finished copy of this drawing is available with the filename 0403_SurfaceBoundary_FINISHED.dwg or (0403_SurfaceBoundary_METRIC_FINISHED.dwg).

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Adding Boundaries

Crossing Breaklines

noreply@blogger.com (CAD Civil 3D) — Mon, 15 Aug 2022 18:00:00 +0000

Eventually, you will see Panorama pop up with a message about crossing breaklines. In general, Civil 3D does not like breaklines that cross themselves. The Resolve Crossing Breaklines tool will let you examine those situations. To use the Resolve Crossing Breaklines tool, do the following:

Click a surface with breaklines.
From the TIN Surface contextual tab ➢ Analyze panel, choose Resolve Crossing Breaklines.
At the Please specify the types of breakline you want to find or [surveyDatabase Figure Surface]: prompt, enter S ↲ to select the surface option.

The Crossing Breaklines tab on Panorama lists the crossing breaklines. You can decide how you want to resolve them using Use Higher Elevation, Use Lower Elevation, Use Average Elevation, or Specify Elevation, as shown here.
Select each breakline and click the Resolve button, which is located underneath the drop-down list shown in the preceding image; the conflict disappears from the Crossing Breaklines conflict list.

The Yellow Exclamation Point Flag

noreply@blogger.com (CAD Civil 3D) — Thu, 11 Aug 2022 18:00:00 +0000

At some point you are bound to see a yellow exclamation point status icon in Prospector. This is a flag showing you that some elements are out of date and require rebuilding. In the image shown here, the EG surface needs to be rebuilt because the Point Groups branch is out of date.

No matter what type of definition in a surface is out of date, to rebuild the surface, right-click the surface’s name (in this example that would be EG) and select Rebuild. You could also select Rebuild Automatic, which would result in the surface always rebuilding when required instead of you always having to manually select Rebuild.

Supplementing Factors

noreply@blogger.com (CAD Civil 3D) — Wed, 10 Aug 2022 18:00:00 +0000

Turning on Supplementing Factors in the Add Breaklines dialog enables you to add additional surface points along your breaklines. Doing this helps to eliminate the generation of long triangle lines. It also allows you to define breaklines more precisely along curves.

The Distance setting works like the AutoCAD measure command. When breaklines are added to a surface, Civil 3D will add additional vertices based on this increment value.

The Mid-ordinate Distance setting is applied to arc segments in your breaklines. If this setting were absent, the program would create a single breakline segment from the PC to the PT of the arc. With this setting in place, the program creates shorter segments along the arc. With each segment considered to be tiny chords, the Mid-ordinate Distance value is the resulting measurement from the midpoint of each chord to the midpoint of each segmented arc.

In this example, you’ll add some breaklines that describe road and ditch features:

Open the 0402_SurfaceFromBreaklines.dwg file or the (0402_SurfaceFromBreaklines_METRIC.dwg) file.
This drawing is similar to the drawing used in the first exercise. It contains a surface created with a point group. It also contains 3D survey figures. Without the survey database, you’ll have to add the figures conventionally, meaning through the Breakline branch of the surface.
Inspect the drawing by panning and zooming along the linework.
Notice that the TIN lines are not drawn along the figures representing the edge of pavement, centerline of roads, flowline of ditches, and top of banks.
Select and then right-click one of the brown figures representing the top of bank, and choose the Select Similar option.
The tooltip will indicate a figure prefix style of TB.
All the brown figures representing the tops of banks are now highlighted.
In Prospector, expand the Surfaces ➢ Existing Surface ➢ Definition branches.
Right-click Breaklines and select the Add option.

The Add Breaklines dialog appears.

Enter the description Top of Bank and leave all other settings at their default, as shown in Figure 1.
Figure 1: Entering a description in the Add Breaklines dialog.
Click OK to accept the settings and close the dialog.
You can dismiss Panorama if it appears.
Repeat steps 3–7 for figures DL (Flowline of Ditch), BB (Bottom of Bank), CL (Centerline of Road), and EP (Edge of Pavement).
Zoom extents and notice that the TIN lines are now running along the survey figures now acting as breaklines.

As shown in Figure 2, by adding the breaklines, you force the TIN lines to align with them, thus cleaning up the contours and making them follow the ridgelines of the road centerline, gutter lines, and shoulders as well as the changes in grade around the small detention area.


Figure 2: Existing surface with contours displayed before breaklines are added (left) and after (right)

When this exercise is complete, you can close the drawing. A completed version of this drawing is available with the filename 0402_SurfaceFromBreaklines_FINISHED.dwg or (0402_SurfaceFromBreaklines_METRIC_FINISHED.dwg).

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Breakline Types
Weeding Factors
Supplementing Factors

Adding Boundaries

Weeding Factors

noreply@blogger.com (CAD Civil 3D) — Tue, 09 Aug 2022 18:00:00 +0000

Turning on Weeding Factors in the Add Breaklines dialog allows you to omit extraneous data from your surface. You will want to consider weeding when your breaklines contain a lot of vertices very close together. Each vertex is added to your surface as a point, so when you weed, your aim is to exclude extraneous point data. This not only reduces the size of your surface but helps to eliminate the formation of skinny triangles, which can produce saw-toothed contours.

Weeding requires that a distance and angle be entered in the Add Breaklines dialog. With these settings, the program will examine each vertex as follows:

It measures the length of the segment leading into the vertex.
It measures the length of the segment leaving the vertex.
If the sum of both lengths is less than the entered distance value, it checks the delta angle.
If the delta angle is less than the entered angle value, it omits the vertex.

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Adding Boundaries

Breakline Types

noreply@blogger.com (CAD Civil 3D) — Mon, 08 Aug 2022 18:05:00 +0000

No matter which method you use to add breaklines to a surface’s definition, you will need to configure the type of breakline that it is. The breakline types are as follows:

Standard: Standard breaklines can be 2D or 3D polylines, arcs, lines, splines, feature lines, figures, or parcels. These entities have the actual elevations for the surface assigned at their vertices. The vertex elevations become surface points, TIN lines are drawn along the breakline, and then the remaining triangulation is calculated. Standard breaklines represent both the horizontal and vertical locations of linear features of a surface.
Proximity: Proximity breaklines represent horizontal location only. In fact, if the entity used to define the proximity breakline is 3D, the vertex elevation will be ignored. The elevation of each vertex is determined from a nearby surface point already added to the surface.
Wall: Wall breaklines can be used to define near-vertical drops such as retaining walls or curb lines. You would define a wall breakline much the same as you would define a standard breakline. After selecting the feature, you would define a horizontal offset side and then an elevation difference at each vertex or for the entire length of the feature.
From File: The From File option is needed only if you have an FLT text file containing breakline data. This file type is usually the result of output from another program and contains XYZ data on each vertex for the lines described in the file. Once the FLT file has been imported, the effect on the surface is identical to a standard breakline. File Link options can be dynamically linked to the file, or the link can be broken so the surface will no longer be dependent on the file.
Non-destructive: Non-destructive breaklines neither change elevation nor change grades of the surface model. Non-destructive breaklines simply control the horizontal orientation of triangle lines. You may find yourself needing a non-destructive breakline in anticipation of cleaning up triangle data, as discussed later in this blog, in the section “Manual Surface Edits”.

By far, standard is the most frequently used type of breakline, followed by proximity and wall breaklines.

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Adding Boundaries

Adding Breaklines

noreply@blogger.com (CAD Civil 3D) — Mon, 08 Aug 2022 18:00:00 +0000

Breaklines change the triangulation of a surface by forcing triangle edges to follow along the segments of the breakline. Breaklines represent linear features where a change in the slope of a surface occurs. Examples of such features would be ridges, streams, ditches, curbs, and retaining walls, just to name a few.

There are several methods for adding breaklines to a surface. On the Prospector tab of Toolspace, you can select the Breakline branch of the surface definition, right-click, and select Add. Additionally, you can easily add survey figures by going to the Survey tab of Toolspace, right-clicking the Figures branch, and selecting Create Breaklines. When feature lines are selected, an Add To Surface As Breakline option is displayed in the contextual tab.

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Adding Boundaries

Creating a Surface with Point Groups

noreply@blogger.com (CAD Civil 3D) — Thu, 04 Aug 2022 18:00:00 +0000

Usually, existing surfaces are created from data collected from topographic surveys. From that data, a set of relevant surface points can be isolated by defining a point group. This point group is a quick means of adding point data to a surface definition. Point groups are covered in the discuss of “Points”.

In the exercise that follows, you’ll build your first basic surface with a point group:

Open the file 0401_SurfaceFromPointGroup.dwg or (0401_SurfaceFromPointGroup_METRIC.dwg).
On the Home tab of the ribbon ➢ Create Ground Data panel, select Surfaces ➢ Create Surface.
In the Create Surface dialog, shown in Figure 1, click in the Name field.
Figure 1: Creating your first new TIN surface.
Remove the default text by highlighting it and replacing it with the name Existing Surface.
Set Style to Contours 1’ and 5’ (Background) or Contours 0.5 m and 2.5 m (Background) for metric users and click OK.
In Prospector, expand the Surfaces branch. You should now see your new surface in the listing.
Expand Existing Surface and then expand Definition by clicking the tiny plus sign to the left of the listing in Prospector.
Right-click Point Groups and select Add.
In the Point Groups dialog, highlight TOPO Shots and click OK. You should now see contours for your surface.
Save your drawing at the conclusion of the exercise. Compare your work with 0401_SurfaceFromPointGroup_FINISHED.dwg or (0401_SurfaceFromPointGroup_METRIC_FINISHED.dwg) if desired..

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Creating Surfaces

Creating a Surface with Point Groups
Adding Breaklines

Adding Boundaries

Creating Surfaces

noreply@blogger.com (CAD Civil 3D) — Wed, 03 Aug 2022 18:00:00 +0000

When you first create a surface in Civil 3D, you give it a name and set its style. Initially, your surface will be empty, containing no data; your next step is to add data to the surface definition. In Prospector, you can view the contents of the surface by expanding its branch and then further expanding the Definition area, as shown in Figure 1.


Figure 1: Create a new surface (left). Expand a surface’s definition to add or modify elevation data (right).

The following components can be used as part of a surface definition:

Boundaries: Boundaries are closed polylines that determine data inclusion and visibility for the surface. A boundary can be a 2D polyline, a 3D polyline, or even a feature line, but only the horizontal information will be used to generate the boundary—the elevation of the polyline is ignored. If the polyline that created the boundary is modified, the surface will become out of date.
Breaklines: Breaklines are used to create triangulation paths, thereby preventing triangle lines that could be generated off adjacent points from crossing these paths. Breaklines are mandatory for defining flow lines, curb lines, ditch lines, pavement edges, or any linear representation of ridges or valleys. Breaklines can be defined using lines, arcs, 2D polylines, 3D polylines, survey figures, parcels, or feature lines. Similar to boundaries, if a breakline is modified, the surface will become out of date, thus requiring a rebuild. Breaklines will be discussed in more detail later in this blog.
Contours: Polyline representations of surfaces can be used to create a Civil 3D surface. These polylines must be assigned the elevation of the contour they represent. Points will be placed along the contours to be used in the triangulation process. In addition, algorithms are run to ensure that the Civil 3D contours generated closely match the polyline contours used to define the surface. This process will be discussed in more detail later in this blog in the section “Surfaces from Polylines”. Similar to boundaries, if the polyline contour is modified, the surface will become out of date, thus requiring a rebuild. Adding contour data will be discussed further later in this blog.
DEM Files: Digital Elevation Model (DEM) files are the standard format files from governmental agencies and geographic information system (GIS) systems. These files are typically large in scale but can be great for planning purposes.
Drawing Objects: These are AutoCAD objects that have an insertion point at an elevation (e.g., text, blocks, lines, AutoCAD points, 3D faces, or polyfaces) that can be used to populate a surface with elevation data. For text and blocks, the text insertion point z position is used as the elevation. Changes to these objects will not cause the surface to become out of date.
Edits: Any manipulation after the surface is completed, such as adding or removing triangles or changing the datum, will be part of the edit history. These changes can be viewed in the surface properties, where edits can be toggled on and off individually to simplify reviewing and changing. They can also be reordered since edits are applied in the order in which they are added.
Point Files: Point files work well when you’re working with large data sets where the points themselves don’t necessarily contain extra information. Examples include laser scanning or aerial surveys. A drawing will stay referenced to a point file. If the point file is moved or deleted, the reference in the drawing will be broken unless a surface snapshot is taken. Snapshots will be discussed later in the blog.
Point Groups: Civil 3D point groups or survey point groups can be created to isolate a set of points used to build a surface. The surface is linked to that point group. If points are added, removed, or modified in the point group, the surface will become out of date and must be rebuilt.
Point Survey Queries and Figure Survey Queries: Point survey queries and figure survey queries perform similar tasks. A saved survey query created on the Survey tab of Toolspace can be used similarly to a point group for populating surface elevation data.

If the query contains both points and figures, you can choose to use both types of data, only points, or only figures. Unlike a point group, data from the query can be added without the points or figures being inserted in the drawing. Prior to adding point survey queries or figure survey queries to surfaces, you must open the survey database containing those queries.

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Creating Surfaces

Adding Boundaries

Understanding Triangulation Mathematics

noreply@blogger.com (CAD Civil 3D) — Tue, 02 Aug 2022 18:00:00 +0000

TIN surface calculations are based on computational geometry known as Delaunay triangulation. Delaunay triangulation takes a set of points, isolates three in close proximity, and applies a circle intersecting those three points, producing a triangle. This algorithm is repeated for the remaining points, resulting in a collection of circles called circumcircles, which produce a network of triangles. Elevation interpolation occurs along those triangle lines, which determines where contours are drawn.

It’s important that the points used in surface calculations be a good representation of surface elevations. This means that points representing fire hydrants, power poles, or trees, for example, should be excluded since those points more than likely were not collected at ground level.

Other information we provide to a surface definition influences how those triangles are drawn. Breaklines prevent triangle lines from being drawn through them but allow them to be drawn along them. Boundaries prevent interpolation from occurring inside or outside their extents depending on the type of boundary defined. Surface edits can override the Delaunay triangulation. Surface property settings can be used to apply a set of rules governing how the surface is created.

Understanding Surface Basics

noreply@blogger.com (CAD Civil 3D) — Mon, 01 Aug 2022 18:00:00 +0000

A surface in the Autodesk® AutoCAD® Civil 3D® program is generated using the principle of triangulation. At the very simplest, a surface consists of points. The computer generates a triangular plane using a group of three points. Each triangular plane shares an edge with another, and a continuous surface is made. This methodology is referred to as a triangulated irregular network (TIN), as shown in Figure 1.

Figure 1: A triangulated irregular network or TIN.

For any given (x,y) point, there can be only one unique z value within the surface (since slope is equal to rise over run, when the run is equal to 0, the result is “undefined”). What does this mean to you? It means surfaces created by Civil 3D have several rules:

No Thickness: Modeled surfaces can be thought of as a sheet draped over a surface; they have no thickness in the vertical direction associated with them.
No Vertical Faces: Vertical faces cannot exist in a TIN because two points on the surface cannot have the same (x,y) coordinate pair. Vertical walls or curb structures must have a slight offset of at least 0.001’ (0.0001 m); otherwise, they will appear flattened.
No Caves or Tunnels: The triangular planes that make up a TIN cannot overlap. If a design requires any tunnel-like structures, you will need to accomplish this with several surfaces instead.

There are four types of surfaces in Civil 3D: TIN surfaces, grid surfaces, grid volume surfaces, and TIN volume surfaces. A TIN surface is based on a set of points using Delaunay triangulation. A grid surface is based on a Digital Elevation Model (DEM) file consisting of a set of data points arranged in a regularly spaced grid configuration. DEM files can be obtained from various mapping agencies. Volume surfaces are built by measuring vertical distances between two surfaces. Volume surfaces can be created from two grid or two TIN surfaces.

How to create a point table?

noreply@blogger.com (CAD Civil 3D) — Thu, 28 Jul 2022 18:00:00 +0000

Point tables provide an opportunity to list and study point properties. In addition to basic point tables that list number, elevation, description, and similar options, you can customize point table formats to include user-defined property fields.

Use the DWG created in the previous exercise or start with0312_Exercise_FINISHED.dwg or (0312_Exercise_METRIC_FINISHED.dwg).
Create a Centerline point group to include all the centerline points and create a point table for this point group using the PNEZD format table style.

Solution

In Prospector, right-click Point Groups and choose New.
On the Information tab, enter Centerline as the name of the new point group.
Switch to the Include tab.
Select the With Raw Descriptions Matching check box and type CL* in the field.
Confirm on the Point List tab that all the points have the description CL and click OK.
Change to the Annotate tab ➢ Labels ➢ Tables panel and select Add Tables ➢ Add Point Table.
Choose the PNEZD format for the table style.
Click the Point Groups icon, choose the Centerline point group, and click OK. Click OK to insert the table. Leave the defaults as they are.
The command line prompts you to choose a location for the upper-left corner of the point table.
Choose a location on your screen somewhere to the right of the project.
Zoom in and confirm your point table.
Compare your work to the file 0313_Exercise_FINISHED.dwg or (0313_Exercise_METRIC_FINISHED.dwg).

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How to export points to LandXML and ASCII format?

noreply@blogger.com (CAD Civil 3D) — Wed, 27 Jul 2022 18:00:00 +0000

It’s often necessary to export a LandXML or ASCII file of points for stakeout or data-sharing purposes. Unless you want to export every point from your drawing, it’s best to create a point group that isolates the desired point collection.

Create a new point group that includes all the points with a raw description of SW. Export this point group via LandXML and a PENZD comma-delimited text file.
Use the DWG created in the previous exercise or start with 0311_Exercise_FINISHED.dwg or (0311_Exercise_METRIC_FINISHED.dwg).

Solution

In Prospector, right-click Point Groups and choose New.
On the Information tab, enter Sidewalk as the name of the new point group.
Switch to the Include tab.
Select the With Raw Descriptions Matching check box and enter SW* in the field.
Confirm in Prospector that all the points have the description SW and click OK.
Right-click the Sidewalk point group and choose Export LandXML.
Click OK in the Export To LandXML dialog.
Choose a location to save your LandXML file and then click Save.
Navigate to the LandXML file to confirm it was created.
Right-click the Sidewalk point group and choose Export Points.
Choose the PENZD (comma-delimited) format and a destination file, and confirm that the Limit To Points In Point Group check box is selected for the Sidewalk point group. Also, confirm that all Advanced Options are unchecked. Click OK.
Navigate to the ASCII file to confirm it was created.
Save the file.
Compare your work to the file 0312_Exercise_FINISHED.dwg or (0312_Exercise_METRIC_FINISHED.dwg).

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How to create a point group?

noreply@blogger.com (CAD Civil 3D) — Tue, 26 Jul 2022 18:00:00 +0000

Building a surface using a point group is a common task. Among other criteria, you may want to filter out any points that tend to have erroneous elevations such as utilities or vegetation.

Create a new point group called Topo that includes all points except those with a descriptor code of TREE and HYD. Use the DWG created in the previous exercise or start with 0310_Exercise_FINISHED.dwg or (0310_Exercise_METRIC_FINISHED.dwg).

Solution

In Prospector, right-click Point Groups and choose New.
On the Information tab, enter Topo as the name of the new point group.
On the Include tab, fill the check box for Include All Points.
On the Exclude tab, click the With Raw Descriptions Matching check box to turn it on,and enter TREE*, HYD* in the field.
Click OK to close the box.
Save the file.
Compare your work to the file 0311_Exercise_FINISHED.dwg or (0311_Exercise_METRIC_FINISHED.dwg).

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How to import points from a text file using description key matching?

noreply@blogger.com (CAD Civil 3D) — Mon, 25 Jul 2022 18:00:00 +0000

Most engineering offices receive text files containing point data at some time during a project. Description keys provide a way to automatically assign the appropriate styles, layers, and labels to newly imported points.

Open 0310_Exercise.dwg or (0310_Exercise_METRIC.dwg).
Revise the Civil 3D description key set to contain only the parameters listed next.
Code Point style Point label style Format Layer
GS* Basic Elevation Only Ground Shot V-NODE
EP* Basic Elevation and Description Road Edge V-NODE
HYD* Hydrant (existing) Elevation and Description Hydrant V-NODE-WATR
SW* Basic Elevation and Description Sidewalk V-NODE
TREE* Tree Elevation and Description Tree V-NODE-TREE
Import the PENZD (space delimited) file 0310_Exercise.txt or (0310_Exercise_METRIC.txt). Confirm that the description keys made the appropriate matches by looking at a handful of points of each type. Do the trees look like trees? Do the hydrants look like hydrants?
Save the resulting file for use in the remaining exercises
.

Code	Point style	Point label style	Format	Layer
GS*	Basic	Elevation Only	Ground Shot	V-NODE
EP*	Basic	Elevation and Description	Road Edge	V-NODE
HYD*	Hydrant (existing)	Elevation and Description	Hydrant	V-NODE-WATR
SW*	Basic	Elevation and Description	Sidewalk	V-NODE
TREE*	Tree	Elevation and Description	Tree	V-NODE-TREE

Solution

Open the file 0310_Exercise.dwg or (0310_Exercise_METRIC.dwg).
Switch to the Settings tab of Toolspace, and under the Point Collection locate the description key set called Civil 3D.
Right-click this set and choose Edit Keys.
Revise the three keys to match the GS, EP, and HYD specifications listed under the instructions.
Right-click the EP key and choose Copy.
Edit the copied key to match the SW specifications listed in the instructions. Repeat steps 5–6 for TREE code and exit Panorama.
On the Home tab of the ribbon ➢ Create Ground Data panel, select Points ➢ PointCreation Tools and then click the Import Points icon on the toolbar.
Click the plus white icon to add a file to import and navigate to the 0310_Exercise.txt or (0310_Exercise_METRIC.txt) file. If necessary, change Files Of Type to Text/Template/Extract File (*.txt). Click Open to continue.
Select PENZD (Space Delimited) from the listing, check Add Points To Point Group,and create a point group with the name of your choosing. Verify that everything in the Advanced Options area is unchecked. Click OK. Click OK again to complete the command.
Use Zoom Extents to see the points.
Save the file and keep it open for use in the next exercise.

Note that each description key parameter (style, label, format, and layer) has been respected. Your hydrants should appear as hydrants on the correct layer, your trees should appear as trees on the correct layer, and so on. Compare your work to 0310_Exercise_FINISHED.dwg or (0310_Exercise_METRIC_FINISHED.dwg).

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How Can Civil 3D Work with Soil Boring Data?

noreply@blogger.com (CAD Civil 3D) — Thu, 21 Jul 2022 18:00:00 +0000

There are several options for users who want to work with subsurface data in Civil 3D. One option is the Autodesk Geotechnical Module. This subscription-only tool allows users to import borehole data in several formats including AGS31, AGS4, and CSV and from a Keynetix HoleBASE database.The boreholes created with this tool are not point objects.

The option discussed here involves using user-defined properties on points to enter subsurface data. This option does not require any special downloads. In the following example, you will add user-defined properties to some soil boring points and leverage point groups to work with the data. The skills you learn in this example can be applied to multiple soil boring values for the purposes of creating subsurface data.

Open the file 0309_SoilBorings.dwg or (0309_SoilBorings_METRIC.dwg).
This file contains an existing ground surface together with the property linework for the site using Civil 3D Parcels.
Import into the drawing the soil boring points that are provided to you in a LandXML file byusing the LandXML tool that is on the Insert tab ➢ Import panel.
The file that you will need is located in this data folder and is named 0309_SoilBorings.xml or (0309_SoilBorings_METRIC.xml).
Take a moment to examine the soil boring points and the current elevation listing.
From the Settings tab of Toolspace, expand the Point collection, right-click User-Defined Property Classifications, and select New.
Name the new classification Soil Borings and click OK.
Expand the User-Defined Property Classifications category (if it is not already expanded), right-click Soil Borings, and select New.
Name the new property Watertable Elevation.
Set Property Field Type to Elevation, uncheck Default Value, and then click OK.
Jump back to the Toolspace ➢ Prospector tab and highlight the main Point Groups listing. At the bottom of Toolspace you will see a listing of all the point groups, as shown here.
Set the classification as shown in the previous image.
Right-click the Soil Borings point group and select Edit Points.
Scroll over in Panorama until you locate the new classification column named Watertable Elevation.
This is the information you added in the previous steps.
Add the Watertable Elevation entries in Panorama, as shown here. Dismiss Panorama when you’ve finished.
Right-click the Soil Borings group and select Properties. Switch to the Overrides tab, as shown here.
Place a check mark next to Point Elevation on the Overrides tab.
Click the tiny pencil icon twice or until it turns into the user-defined property icon. Initially the value will be <none>.
Click the field next to the icon to set the value to Watertable Elevation.
Click OK to dismiss the Point Group Properties dialog.

Notice that the elevation labels for the five points are listed as the water table elevations.

To compare your work with a completed example, see 0309_SoilBorings_FINISHED.dwg or (0309_SoilBorings_METRIC_FINISHED.dwg).

User-Defined Properties

noreply@blogger.com (CAD Civil 3D) — Wed, 20 Jul 2022 18:00:00 +0000

Standard point properties include items such as number, easting, northing, elevation, name, description, and the other entries you see when examining points in Prospector or Panorama.
Now, what if you’d like to assign extra information to a point object and the field data for that information is not among the standard fields that ship with the software? Civil 3D is versatile in this situation since it provides the means to add custom fields to suit your needs.

It’s common to receive points from a soil scientist that list additional information, such as groundwater elevation or subsurface elevation. Surveyed manhole points often include invert elevations or flow data. Tree points may also contain information about species or caliber measurements. All this additional information can be added as user-defined properties to your point objects. By using user-defined properties, you will be able to parse the nonstandard information and attach it to the point data during the import process. You can then use user-defined properties in point labeling, analysis, point tables, and more.

Point Tables

noreply@blogger.com (CAD Civil 3D) — Tue, 19 Jul 2022 18:00:00 +0000

You’ve seen some of the power of dynamic point editing; now let’s look at how those dynamic edits can be used to your advantage in point tables.

Most commonly, you may need to create a point table for survey or stakeout data; it could be as simple as a list of point numbers, northing, easting, and elevation. These types of tables are easy to create using the standard point-table styles as a beginning reference. Follow these steps to create a point table:

Open the 0308_PointTable.dwg or (0308_PointTable_METRIC.dwg) file.
This file will appear empty, but it isn’t. First, you will review reordering point group properties to change the display of points. You don’t need to see points to make a point table from a group, but this will help you see that the table reflects the specific group.
In Prospector, expand Point Groups.
You will see that No Display is listed on the top, which means the styles set in its properties are taking over the other point groups.
Right-click Point Groups and select Properties.
In the listing, move the group Corners To Locate to the top by using the arrows on the right. Click OK.
Right-click the Corners To Locate point group and select the Zoom To option to focus on the desired points.
Switch to the Annotate ribbon tab and click Add Tables ➢ Add Point Table.

Verify that Table Style is set to Corner To Locate and click the Select Point Group icon next to the No Point Groups Selected label.
In the Point Groups dialog, select Corners To Locate and click OK.
Verify that the check box next to Split Table is clear.
When all your settings match those in Figure 1, click OK.
Figure 1: Point Table Creation options.
Click anywhere in the graphic to place the table.
Save the drawing.

To compare your work with a completed example, see 0308_PointTable_FINISHED.dwg or (0308_PointTable_METRIC_FINISHED.dwg).