From the course: Autodesk Civil 3D 2020 Essential Training

Sample lines, cross sections, section views, and relations - AutoCAD Civil 3D Tutorial

From the course: Autodesk Civil 3D 2020 Essential Training

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Sample lines, cross sections, section views, and relations

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- [Instructor] In working with linear design a lot of times we or maybe the jurisdiction's regulatory agencies, contractors, or others will want to see our design in a cross-sectional format. Cross-sections really are very similar to profiles. In Civil 3D the presentation of them can be pretty much the same. A lot of the style and information is similar. The information and how it's sampled, that's what's really different. A profile is going to follow the longitudinal path of the alignment, and that's what's sampled. Whereas a cross-section is generally perpendicular to that alignment or baseline, that linear path. You simply want to provide a swath width or an offset to the left and an offset to the right of that alignment, that linear path that you're going to be cutting and sampling. The concept's the same though. You're still cutting the earth at a specific location. It's just the direction or means of how you're going to cut that earth. Now to do cross-sections you're going to need a linear path to create those cross-sections in that perpendicular way. So an alignment is a parent of cross-sections, just as an alignment is a parent of profiles. To create cross-sections, especially ones that can have varying widths or offsets to the left and right, you have a lot of different sections you sample, you create what are called sample lines. So in this drawing that I have open you see the sample lines visually displayed using the style that looks like a little bit of a section. Those are the sample lines. That is the width to the right and left that we're cutting or sampling through the earth. Now all of these, you see how many there are and this is just the subdivision road, because there's so many different sample lines, a sample line group actually contains the collection of sample lines. And that's really a child of an alignment. Now the great power of the sample line group is you can apply adjustments. What you sample, the styles and so forth to the entire collection of sample lines and thereby the associated cross-sections that are cut following those sample lines. We see a lot of information being stored as a child of an alignment. And if we look at our tool space under prospector here, we'll get a better view of exactly all of that relationship that's going on. We have alignments, centerline alignments, we have Oceola Road. Under sample line groups there's a sample line group named Oceola Road, then we have the sample lines. You remember the dot with the square means there's a collection, so I select that. You see all the sample lines, and then you have the sections depending on what was sampled, and their collections as well. There's another child called section view groups. So not only are the sample lines grouped together, so are the section views. Section views, like profile views, are the means to be able to see in our drawing space the sections that are cut. So if I zoom into a section view here, you see, again, there's a lot of similarities to how they can be set up. The real big difference between a profile view and a section view is that sections views are offset in elevations and that's what they're defining here. And so we have a section view group, which is a child of the alignment, really a child of the sample line group which is a child of the alignment, and the section view group allows us to control the order and arrangement of a lot of section views. As we see here there's quite a few, and again, this is just a small subdivision road. So understanding those relationships, again, is key. In alignment, when we erase the alignment, we could be getting rid of profiles, profile views, sample line groups. And sample line groups have children, such as sample lines, sections, section view groups, which have children of section views. It is a hierarchy of collection, that relationship that we talked about at the beginning. So now that we understand those relationships, the very first thing we need to do is create sample lines and their associated sections. Let's do that.

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