Using 3ds Max Design with Civil 3D – Part 15 – Creating Swept Objects


Continue working on your scene from the last movie. You can also use the scene named CP-04_sweeps.max provided to you. Consider the part of the bridge over the water: The geometry that was imported from Civil 3D and that represents the lanes, shoulders and sidewalks is paper-thin. There is absolutely no depth to the bridge as it currently stands. The existing geometry is based on a cross-section that only covers the top of the bridge. In fact, you need another cross-section that includes the side protections, walls/fences, but also the underside of the bridge. You only need that for the part over the water. The bridge ends have sloped areas courtesy of the Civil 3D Daylight sub-assemblies. Obviously, to create the geometry you need, you have to rely on some kind of lofting or sweeping process. These are techniques you could use on their own. Lofting is a geometry creation process while Sweeping is modifier-based. Better yet, you can rely on Civil View’s Swept Object tool that makes the process that much easier. When you’re sweeping an object, you usually rely on the path that defines the length of the sweep. Luckily, This is why you imported the SideWalk_Out-Region(2) feature line earlier from Civil 3D. This feature line is a double line that runs along the outside of the middle section of the bridge. Go ahead and select it. Make sure Civil View is running, and then choose Civil View>Swept Object Style Editor. A dialog appears along with a prompt, asking you if you want to use the currently selected spline as a path. Answer Yes to the prompt. Another appears telling you the selected path is made of multiple splines and if you want to use it in Spannable Geometry Mode. This basically means that you’d be working on both side of the bridge simultaneously; answer Yes as well. Add a new element as you have learned to do. A new surface appears spanning out from the sidewalks. In fact, it does so on both sides of the bridge. Take a look at it so you can understand what’s happening. This new surface extends outward by a value specified in the Start Horizontal Offset field. You can adjust this value, as you can also adjust the vertical Offset value to create walls or noise barriers. You can also change the material for this element, and the mapping. In effect, you need to add multiple elements to build a profile to sweep along the feature line. You could potentially build one from an existing shape, although adding elements manually arguably gives you better control. In this case, you are looking for a profile similar to this. Set this first element with a Hor.Off. of 0 and a Ver.Off. of 0.25 Basically, it’s going straight up by a value of 25cm Also set the Length Repeat mapping to 1 to minimize texture stretching. Add a new element. Stretch it out by 0.1m and up by 0.3m Also adjust the Length Repeat to 1m You may want to enable Edged Faces mode (F4) temporarily, this way, you can better see how the swept object is lining up. Add a new element, this one doesn’t stretch out but needs to go up 0.5m Again, mapping needs to be adjusted; set the Length repeat to about 2. Add another element for the top of the wall. Stretch it out by 0.4m with no height. Adjust the mapping. Now you need to come down on the other side. Add a new element and set it to go down by specifying -1.5m Adjust the mapping. To wrap around the underside of the bridge, it may be a bit difficult to see. Consider using Wireframe mode temporarily using the F3 toggle. Add one more element and set it to -1m offsets to sweep in inward and down. Set the mapping about the same as the last element you created. Adjust your view. At this point, you get to decide how to connect the left side to the right side. Spanning Surface connects the “first points” of your established new profile. Closing Surface connects the “last points” of the profile. If either of these two options is disabled, you won’t be able to cap the extremities of your newly swept object. If you don’t want the ends of your swept object to be hollow, then you need to enable all three options. Here’s the problem: Press F3 to go back to shaded mode. In this particular case, enabling Spanning Surface hides the work you’ve done on the bridge previously. The reason is that the swept object is based on a feature line at the same level as the sidewalks. The sidewalks are higher than the road, which slopes down as it nears the sidewalks. With the spline (feature line) still selected, move it down in Z by a relative -0.25m displacement. This should make the profile work to your advantage. You still need a fence as the current height of the wall is not protective enough. Select the fourth entry in the list. It represents the top of the wall. Change the Horiz Offset to 0.2m and then copy and paste the element. You’re back to the original width except that it’s now divided in the middle. Again, select the fourth entry and add a new element underneath it. Set the new element to go 1.2m in height and no horizontal offset. Set its material to [30] Railing Type 2, you’ll adjust that in a moment. You took the fence up but it needs to go back down for the rest of the profile to resume where it left off. Copy and paste the railing element. Also make sure the lower railing entry has a negative height. Looking at the railing, it seems obvious there are some smoothing issues creating a flicker effect. This happens sometimes when two surfaces close to one another share the same smoothing group. Because the two elements defining the fence are basically duplicates, they are both on the same smoothing group. Set them in a way that no two subsequent elements are using the same Smoothing Group value. In order to see the fence map in the viewport, you need to make some slight adjustments in the Material Editor. Open the Slate Material Editor and create a new view. Name it “Sweeps”. Sample the material from the swept object you are working on. An elaborate Multi/Sub-Object material displays. Double-click the main node to see what it is made of. In fact, click inside the Sweeps view, press Ctrl+A to select all nodes and then choose View>Open/Close Selected Nodes. This collapses all the nodes and you can now lay them out for a better view. Actually, expand the main node again so you can see the connections to the fifty or so sub-materials also seen in the panel. You’re interested in the Railing Type 2 map which is obviously identified as sub-material #30. Go to this material by double-clicking its node in the view. It is a simple Arch & Design material with a cutout map that you need to adjust. Double-click the map node to edit it. Click the View Image button to take a look at it. It’s a simple black & white image. When used as a Cutout map, white pixels are opaque and black pixels ensure transparency. You can also crop the image and apply the change. In this case, it will make tiling a bit easier for this particular project. Finally, adjust the W-Angle to read 90-degrees to give the image a quarter turn. Make sure the material is set to show in the viewport, and close the Material Editor. If you need to make further mapping adjustments, you can go back to the material editor. You can also adjust the Length Repeat and Width Tiling values of both railing elements. Once you have created a style that you like, you can save it to your Private Resource Kit. Go ahead and do that if you want and note that a Swept Object Style is saved to the .sos format. If you happen to receive one such file from a colleague or a contractor, you can add it to your library as well. Click the Open button, and select your Private Resource Kit. Click the Import File button in the upper right corner of the dialog. Navigate to your C3D_to_3dsMax folder and choose the file: myBridge_csec.sos Once it is imported, select it and click Open. It is similar to the one you created with the addition of a sloped fence piece on top. Close the dialog and take a look at your scene. The bridge section is no longer paper-thin and now has a volume. If you want, you can delete the Sweeps View in the material editor now that you’re done with it. It won’t affect the changes you’ve already made and the large material tree wouldn’t need to render the next time you open the material editor. In the next movie, you continue adding components in the form of static objects such as lamp posts, gantries and signs.

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