Join Jeff Bartels for an in-depth discussion in this video Creating a surface from point data, part of Civil 3D Essential Training.
- After inserting points and connecting the dots, the next step in building an existing conditions model is to simulate the existing terrain. We do that by creating a surface from the point data. This surface is then used to provide the real world context for a proposed design. In this lesson, we'll build a surface from point data. On my screen is a drawing that represents a rural intersection. This drawing was created from surveyed points. To build a surface from this point data, I'm going to come up to the Create Ground Data panel, I'll open the Surfaces menu and I'll choose Create Surface.
In the Create Surface dialogue box, I'll click in the Name field and we'll give the surface a name, I'm going to call it EG for existing ground, and I'll press Enter, I can then add an optional description. I'm going to click in the Style field and I'll click the Ellipsis button and I'm going to choose a style called Contours 1' and 5' background and I'll click okay. This way my surface will have an existing conditions look and the contours will be at a one foot interval. Now, the surface has been created, we just don't see it yet because it doesn't have any data to triangulate to.
If I come over to the Prospector tab and expand the Surfaces category, we can see that existing ground surface right here. I'm going to click to expand that surface and then I'll click to expand its definition, and right here we can see a listing of all of the data items that I can add to this surface to triangulate to. I'd like to add a point group, I'll do that by right-clicking on Point Groups and I'll choose Add. In this example, I'd like to triangulate to all the points, so I'll choose the All Points group and I'll click okay.
As fast as I click okay, we can see that the surface has been built, and the contours now display onscreen. Obviously, we have some problems, that's all right, that's why we're here, to identify and correct problems. Let's see if we can figure out what's going on. I'm going to select the surface and then I'll come over to the Properties palette and I'll change the style. I'll do that by opening the Style setting and I'll choose Contours and Triangles, and I'll press Escape to deselect. You see, when a surface is built, Civil 3D creates the terrain by connecting each point to all of its neighbors, the result is a triangulated mesh, otherwise known as a TIN.
TIN is an acronym, it stands for Triangular Irregular Network. I'm going to zoom out, this triangulated surface reflects light, let's take a look, I'm going to open the Viewports menu, I'll go Viewport Configuration List and I'll choose Two: Vertical. In the view on the right I'm going to zoom in, I'll focus my view on the west end of this road, I will then click in this view on the left and I'll center the geometry onscreen. I will then go back to the right view and I will open the Visual Style menu and I'll choose Shaded.
As you can see, the surface is reflecting light, in fact, it looks pretty good, I've got good definition on this road, at least until I get to this area. You can see we've got a nice edge here at the northern edge of pavement where it's triangulating down to the ditch here on the north side. When we get to this area, though, for some reason it's triangulating from the center of the road all the way down to the ditch. I've got another problem here just to the south, here it's triangulating from the edge of pavement, going across the ditch to these trees on the other side. Let's pan this over and I'll zoom in.
Here we have another anomaly, I've got nice road definition until I get to this area. For some reason, here it's triangulating from the center line of the road to this sign shot. Let's look at the surface another way, I'm going to select it in this view on the left, and I'll come up and choose Object Viewer. Here I'll click and hold the left mouse button and push away to orbit my view. Right there we can see another problem, looks like I have a point shot that's at a very low elevation, possibly zero, we'll have to correct that.
Also note, when I release the mouse button, the appearance of the surfaces changes. This surface style uses alternate properties when the surface is viewed in 3D. By switching the color to orange, it makes the triangulation stand out a little bit better. Let me pan this over. Here on the east side we have another issue, we can see the road coming through right here but then, for some reason, in this area it appears that everything is triangulating to this one point here in the south ditch. I'm going to click to close the Object Viewer and then we'll zoom out in this view on the right, and then I'll press Escape to deselect the surface.
As we look at the initial surface, it's important to note that Civil 3D doesn't really know what the existing site looks like, it's just triangulating the points using a nearest neighbor approach. Many times, we'll need to go in and modify some of the triangulation to create a truly accurate representation of the existing terrain. Let's put this back to a single view, I'll do that in the view on the left. I'll open the Viewport menu and I'll choose Maximize Viewport. In the next few lessons we'll explore several workflows for reviewing and editing surfaces. Along the way we'll continue to make corrections to this surface, such that it accurately reflects the existing conditions.
- Exploring the design data in drawings
- Creating, connecting, and grouping points
- Customizing label styles
- Defining existing ground surfaces
- Designing horizontal alignments
- Controlling alignment properties
- Creating profiles and profile views
- Sharing design data
- Creating and managing parcels
- Building assemblies
- Modeling advanced roadways
- Defining gravity-based pipe and pressure pipe networks
- Creating sections and section views
- Analyzing designs
- Generating plan sheets
Skill Level Intermediate
AutoCAD 2015 Essential Trainingwith Scott Onstott8h 35m Beginner
AutoCAD: Tips, Tricks, and Industry Secretswith Jeff Bartels3h 48m Intermediate
Up and Running with Civil 3Dwith Jon Michael Roberts2h 31m Beginner
Basic Roadway Design with Civil 3Dwith Eric Chappell2h 47m Beginner
1. Laying the Foundation
2. Creating and Managing Points
3. Defining Existing Ground Surfaces
4. Designing Horizontal Alignments
5. Creating Profiles and Profile Views
6. Sharing Design Data between Drawings
7. Creating and Managing Parcels
8. Creating Basic Roadway Models
9. Exploring Advanced Roadway Modeling Concepts
10. Modeling Gravity-Based Pipe Networks
11. Modeling Pressure Pipe Networks
12. Managing Sample Lines
13. Creating Sections and Section Views
14. Exploring Grading Tools
15. Analyzing Designs
Using the Inquiry Tool6m 7s
16. Generating Plan Sheets
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