Recently, I started working on a design for a high-end residential community. The development is in the early stages, and I will be working on the modeling of the existing terrain and lot layout. Once this is finished, I will be working on adding proposed roads and landscape elements. The overall goal of my work will be to correctly model the existing conditions of the site and the integration of the developer's vision for roads and siting of homes. This is an exciting project for me, as I will be working to help visualize some of the landscape conditions which will in turn inform the siting of the residences - the developer will need to consider things such as access to views from various points on each lot, as well as sun, shade, and privacy. For this reason, my modeling of the terrain and landscape features must be 100% accurate, and my graphics will need to effectively communicate the varying nature of the landscape so that the developer and architect can make informed decisions about their siting and positioning of the residences. In these tutorials, I will walk through the creation of an accurate, realistic topographic model with roads and landscape elements. I will begin with a CAD survey of the site contours. I will also have a CAD plan of the unbuilt roads. From these documents, I will be able to create and sculpt the site terrain, adding roads and landscape features such as trees, grass, and other vegetation. The end result will be a realistic, rendered set of images which will depict the terrain and the elements being included by the property developer and architect.
I begin with a survey of the property, which is a hilltop with some very steep grades. Fortunately, the survey came with assigned contour elevations - otherwise I would need to manually assign each contour elevation within AutoCAD. Below is the CAD file:
I don't need to do anything with the CAD file except save it and close the document. My next step is to model the terrain from the existing contours. This part is simple: I open SketchUp Pro, go to File > Import, and under Files of Type, I select ACAD Files (*.dwg, *dxf). It took about a minute, but my contours have imported correctly, with the proper elevations:
My final step is to create a TIN (Triangular Irregular Network) from the contour lines. Basically, when a TIN is created, hundreds or often thousands of small triangles are created, which all connect to make a large mesh that appears as a single surface. The more triangles, the more complex the terrain model is - sometimes too complex. We'll see how complex my terrain model ends up. For now, my focus is simply on creating the TIN; later on we'll see if it needs to be simplified.
To create the TIN within SketchUp, I first need to enable something called Sandbox Tools. To enable Sandbox Tools in SketchUp, I do the following:
1. First, I open the Extensions Manager. On a PC, this is done by going to Window > Preferences > Extensions. On a Mac, this is done by going to SketchUp > Preferences > Extensions. 2. Next, I locate Sandbox Tools and check the box next to. 3. Finally, I click OK.
The next step is to explode my contour model. When I imported it, the contours came in as a single group, and I need to separate the group into individual lines. Here what what the contours looked like when I first imported them:
Exploding is easy - I simply right-click on the contour lines, and select Explode. This process may take several minutes, and it may seem like SketchUp is totally frozen. This is where patience is a virtue - you might be waiting 5 minutes or more for your contours to explode.
Now that I've exploded my contours, I need to go further. The reason is that now each contour line is separate, but the lines themselves are still groups. Below is what the model now looks like:
With all of the lines still selected, I simply right-click and once again click Explode. And I wait...success! My contour lines are now completely exploded. There are no blue boxes around anything, and instead only blue lines. Below is an image of what this looks like:
Now comes the fun part. I am about to create a 3D model from these contours! With everything still selected, I now go to Draw > Sandbox > From Contours. Once I do this, SketchUp starts the long process of modeling triangle faces from the various contour elevations. This can take several hours and honestly, it's best not to use the computer while this process is ongoing. As I mentioned before, SketchUp may appear to be frozen, but it's not - it's just performing thousands of calculations to figure out how to create the triangles in the terrain.
I usually save the step of Draw > Sandbox > From Contours until late evening, and let the process run overnight. When I wake up I am greeted with this image:
This is my completed TIN model! If I rotate my view to the side, I will be able to observe the complex terrain that has been created from the CAD lines:
That's all there is to it. From here, I can begin texturing my terrain and adding roads, trees, and other features.