Join Josh Modglin for an in-depth discussion in this video Creating grading objects, part of AutoCAD Civil 3D Essential Training.
- [Narrator] Now that we understand how Civil 3D uses grading criteria so as to automate the grading, let's go ahead and create some Grading Objects. We're going to open up our exercise here, 13_02_GradingCreate, and we see that existing feature line that we've been working in in chapter 12, and it's located here. We're going to go to the Home ribbon, Create Design panel, and we're going to choose Grading. From there, we're going to open up the Grading Creation Tools. Grading Creation Tools is a toolbar very similar to what we've been working with in so many other facets, alignments, profiles, pipe networks and so forth.
As usuall, we work from the left to the right. As we add Grading Objects, the end result of a grading object is a feature line, and so we're grading from a feature line to a feature line, and the grading object of course is just a part of automating that feature line elevation at the end. Now we've talked about how feature lines interact with one another, and really belong in sites. Because we can have so many grading objects, we're going to group them together in a site.
We're going to click on the far left button to set our grading group. Because there are no current grading groups in the drawing, it recognizes that we need to go ahead and create one, so we're going to name it "Pond." I usually name the grading group the same as the site, because it's rare for me to ever find a need to create more than one grading group per site. I also love this feature. It allows us to create a surface automatically from the grading group.
In other words, what it's going to do is it's going to add the feature lines and the group information as break lines and definition to our surface. In addition it will recognize outer boundaries and hide boundaries based upon the feature lines we select. It gives a great visual to make sure that as we grade, we're grading in a way that is accurate for our proper model. I'm going to go ahead and click OK. Because I said Automated Surface Creation, it pops up and says, "Okay I'm about to create a surface.
"Here are all the settings." Just confirm. They look good. I click OK. I'm currently in my Grading Group called Pond. My surface that I'll grade to is Existing Grade. Then of course we can change the layers. We can also change the set that we're working in. In this case, we only have one set in the drawing, and there's a few different criteria that's available to us. Now we go back again to the first exercise.
We talked about and presented what we were going to be doing. We're going to be coming from the bottom of the pond. That's that feature line we see here, and we're going to an absolute elevation of 737. How we're going to get there is by a slope of three to one. Before we do that, let's just compare and get an understanding of the bottom of our pond. We're going to use the Elevation Editor to see the elevations. You see that the elevations are not constant, but generally the bottom of the pond is 734 or deeper.
What was done is everything is grading from these points here at one percent down to our low point where we'll outlet here. Because of that, let's go ahead and select our criteria. We're grading ... Or better yet we go at a three to one slope to an absolute elevation. We have the criteria. Now we can add a Grading Object. It asks us to select the feature. This is our base point, where we're starting from, so it's the bottom of our pond.
It says which direction are we grading from the bottom? In this case, we're going out. Are we going the entire length with our grading? Yes, and what is the absolute elevation? 737. I press enter. It is now going to prompt me for the slopes. Now you remember in our last exercise, we set these slopes and locked them. If we had locked them in this exercise, we would not be prompted. Notice the name of our criteria does not match our first exercise.
Our first exercise was three to one to elevation. This criteria's named Slope to Elevation. It's a little bit more generic. We'll look at the benefits of that in a minute. I'm going to go ahead and type in three for both the cut and the fill. Our Grading Object is drawn with those projection lines. The feature line which is the end result is drawn, and automated surface with the contours is added. It's prompting me already again to do additional grading.
The next portion of our grading is the ledge. Let's see if we can select the correct criteria to create that flat ledge. We're going to Grade to a Specific Distance. Notice it never ended the command to select the feature, and so I select the newly created feature line from the last Grading Object. We're going the entire length at a distance of three feet. The grade, again we want some positive grade. We don't want it to be flat, so we'll say two percent.
It adds that feature line as well with additional information along the grading object. The next portion of our pond, a slope to a specific or absolute elevation. Notice again, I haven't even ended the command. I've just changed the criteria during the command. I'm going the entire length and elevation of 740. Our slopes for both cut and fill are three to one. Now as you're building, recognize one Grading Object is referencing another Grading Object, which is referencing another one and so on.
The more connections we have, the slower it's going to get, as it's really automating a lot of information all at once. Next we're going to add our berm, and that's Grade to Distance, just as our flat ledge. I'm going to select the top of our pond there, 740 feature line. We're going the entire length. The width of our berm is eight feet, and we're going a distance of two percent. Now that we have the top of our berm and the pond, now we just have to grade down or up depending of course, on tying into our existence grade.
In this case, we are sloping to a surface. Select that last feature line that was created. We're going the entire length at a slope of three to one. Now again, this is going to take a little bit longer as it's tying into an existing surface model, reading those triangles, and adding the information. That quickly, we've created our pond. You can tell just from the styles of the grading objects when we're in cut and when we're in fill.
How accurate is this surface? Let's take a quick look at it in 3D. A well-defined model of our surface. We see it tying in. We have some cut here. Most, of course we're in fill over on this end. There's one little caveat. We don't have a bottom of a pond. Next exercise, we're going to look at how we can add the information to our surface model to include the bottom of the pond.
This course gets you up and running with AutoCAD Civil 3D. First, instructor Josh Modglin shows how to model a surface, lay out parcels, and design geometry, including the making of horizontal alignments and vertical profiles. Next, Josh demonstrates how to create corridors, cross sections, pipe networks, and pressure networks. Then, he covers working with feature lines and grading objects, and how to share your data. He wraps up by providing an overview of plan production tools.
- Navigating the Civil 3D interface
- Using point groups and description keys
- Importing survey data
- Managing figures
- Creating and analyzing surfaces
- Creating parcels
- Working with alignments
- Working with profiles and profile views
- Working with assemblies and subassemblies
- Creating Basic and Advanced Corridors
- Using an Intersection Object
- Making sample lines, cross sections, and section views
- Creating a pipe network
- Understanding pressure parts
- Creating and editing feature lines
- Creating and editing grading objects
- Sharing and referencing data
Skill Level Beginner
Some of the exercise files do not properly function.
This course was built to work with the latest release of AutoCAD Civil 3D. If you are not running AutoCAD Civil 3D 2018 there are some exercise files that will not work for you.