Tipniques: On the Surface, It’s All About Style!

November 6th, 2012

I’m always entertained by how many people have no idea what civil design actually is. I go to parties and someone invariably asks what I do. When I say that I work for a civil firm, I get the extended “Ummmm . . .” response as they try to figure out if I work for an extremely polite company. Eventually, they work up the courage to ask what that means, and I explain it to them like this: “When it rains, the water doesn’t flow into your house; it runs out into the street and magically disappears, right?” To which they always give a surprised: “Hey, yea, it does!” I explain that I design the yard and road surfaces that keep them from needing a snorkel every time they go downstairs. It’s a simplistic explanation, sure, but it’s a pretty accurate description of what we do in the civil world. We are all about surfaces, and in Civil 3D, surfaces are all about styles.

The strength of Civil 3D is that most of your design features are intelligent objects instead of individual components that need to be redrawn and updated every time you make a change. This is obvious in the most important of all C3D objects: the surface. Surfaces are no longer an external text file that has to be re-read and re-built for each modification; it’s a physical object inside your drawing that will graphically update as you make changes to the design. The key of course is controlling those graphic updates so that you’re getting the output you need for your construction documents. Like all objects in C3D, surface display is controlled by a “display style” setting from the C3D Toolspace palette. There, you can develop as many different display options as your imagination can come up with, so you can change the look of your entire surface with a quick click of the mouse. Let’s go through the process of developing a display style for surfaces in C3D.

On the Settings tab of your Toolspace, expand out the Surface category, highlight Surface Styles, right click on it, and select the New option as shown below.


Creating a New Surface Style
This will bring up a dialog box with tabs (below) that give you complete control over how your new surface style will display on screen. Each tab controls options for all the types of data used to build and display your surface. We’ll look at each tab as we put together our new style.


Information Tab
The Information Tab lets you name your style and add a description so that users can easily tell how the style will show on screen, before they select it. It also keeps track of who is creating/modifying the style in case there are questions about it later on.


Borders Tab
On the Borders Tab you determine whether or not the outer border of your surface is displayed and in what manner. The Border Display Mode lets you draw the border at its actual elevations along the surface, at a set elevation, or even at an exaggerated scale if you need it. Border Types is where you decide whether or not to show the outer and hidden boundaries (surface limits and interior structures) on your surface. If the Display Exterior/Interior Border options are “true”, the border types display, if “false”, they won’t. Note that a “true” condition for interior borders essentially creates a mask from your structure, so nothing under it displays in your drawing. This is how you keep contouring and other data from displaying inside buildings. The Datum option allows you to set your border to a specific datum elevation, which will only be visible in a 3D view.


Contours Tab
On the Contours tab you set how contours will show on your plan. You can set Contour Ranges that will shade in between elevations you select with differing colors. The ranges you have chosen and the color/line weight for each is displayed in the window at the bottom of this screen.  3D Geometry controls whether or not your contours are drawn at their actual elevations or flattened down to one you choose (usually 0.00). Legend allows you to pick a table style that will show a graphic legend on your drawing so folks know exactly what they’re looking at. Contour Intervals is the most important setting here. It lets you control the elevation spacing between displayed contours. In the example above, you can see that this style will only display major contours at 10 ft. intervals and the minors every 2 ft. You can also turn Contour Depressions on/off and control some of the options for Contour Smoothing to make your plan look nicer.


Grid Tab
The Grid tab allows you to display your surface as a grid with horizontal and vertical spacing at a flat elevation or as a true mesh with actual elevations at each grid intersection. I have to say though that in 20+ years in the civil field, I’ve never had a need to display a surface this way. I’m sure someone out there must though or they wouldn’t have bothered putting it in here!


Points Tab
Now, the Points Tab is one that I use all the time. Here you can set the values for how surface points are displayed on your plan. You can control the symbol displayed, whether or not it comes in at a real elevation, even set the size/scaling options for the points. Surface points are how you adjust your surface elevations in between contours, to fine tune it, and this tab controls how those points are shown. This is an important tool for creating finished grading plans.


Triangles Tab

The Triangle Tab may seem simple, without a lot of settings, but it’s vitally important. At the end of the day your surface is a TIN (Triangulated Irregular Network), an assembly of triangles with elevations at each vertex. I always set the 3D Geometry here for “Use Surface Elevation” so that I can use 3D views to get a good idea of exactly what my surface is doing. I’ve never had a need for setting the triangle down to a flat elevation. To my mind, it seems to defeat the entire point of displaying them.


Watershed Tab

The Watershed tab is almost an entity unto itself. Here you can control how all your watershed types and areas are displayed. From point control, to elevations and printed legends, all your default watershed surfaces are controlled from this dialog. All the various watershed types listed have the same control options as the one displayed in the above image.


Analysis Tab
The Analysis Tab is a favorite of mine. Here I can set parameters for coloring in my surface. It makes me feel like I’m five years old again! I can set “ranges” that will shade in portions of my surface based on the Elevations or the Slopes of the surface triangles. It’s not unlike the contour shading from above, but this method has more accuracy, shading individual triangles on the surface and not just between contour elevations. I’ve always used this tool for doing steep-slope analysis and looking for any notable discrepancies in my surface build. Just set the number of ranges (elevation or slope) you want to display and choose a color for each. Civil 3D colors in your whole surface in seconds so you can see what areas need your attention.


Display Tab
The Display tab may seem redundant since this entire discussion is about building display styles for surfaces but of all the tabs we’ve looked at, this is the most important one. As you can see, it’s essentially a layer control dialog. It lets you turn on/off the various components we’ve talked about for your current style. Even if you ignore all the other tabs, you’ll want to set the controls here. In the example above, you can see that this style is set to display only the major, minor, and user contours, along with the slope arrows for my surface. Note that I can also control what layers each component type is drawn on and what linetypes and lineweights each has. This is the true heart of controlling your surface display.

The last tab is the Summary tab and it’s just displays all the settings from the other tabs in a single, expandable, list for quick access, I almost never bother with it because I like the focus of each individual tab.

All that’s left is to save this new style, assign it to a surface, and start plotting out your plans! Well, I suppose there is a bit more to it than that (there’s the whole designing of the surface model thing to contend with) but at least now you know exactly how to make that surface display exactly the way you want it to!

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James Coppinger is the CADD & Training Specialist for Maser Consulting, P.A., one of the largest civil engineering firms on the East Coast of the United States. With over 25 years in the CAD industry, working for multiple disciplines, James brings both extensive technical skills and solid understanding of real world business concerns to any CAD discussion. James is also the Site Guide for the cad.about.com web site, one of the premiere sites for CAD discussions, tutorials, and software reviews. You can follow him on:

Facebook - http://www.facebook.com/pages/Aboutcom-Computer-Aided-Design
Twitter: @About_CAD
E-mail: jcoppinger@maserconsulting.com

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