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Typically, you can't finish a construction cost analysis without calculating some areas and when it comes to finding the area of several shapes, you might be tempted to reach for your calculator. That calculator however is not necessary. In this lesson I'll show you a quick way to use AutoCAD to calculate the total area of several shapes in a drawing. On my screen I have a civil engineering example. This is a drawing of a site plan for a proposed restaurant and parking lot. Let's say that the owner of this property would like to finish this project by installing some sod and they would like to cover the area from the property line to the new construction.
They would also like to cover each of these two islands. So, our goal is to find out how many square yards of sod will be required to finish this site. I am going to start by turning off a layer. I don't need these dimensions. I have a feeling they're going to get in my way. So I'm going to click the Layer Off button. I'll select one of the dimensions and then I'll press Enter. If you take a look at the layer control, you can see I have also created a layer called Area and I've set that layer Current. To trace the areas where we will be installing sod, I'm going to use the Boundary command.
So I'll open the Draw panel. I'll launch Boundary. I'll click OK and then I'll click inside this area. I'll click inside this island, and this one and then now click inside this area. And notice that AutoCAD is giving me a warning that says, hey! We cannot find a closed boundary down here. That's all right. I am not going to panic just yet. I'll click Close and then I'll press Enter to accept the three boundaries that AutoCAD did find. Now let's pan this drawing up and I'll zoom in on the southern portion of the site.
Notice AutoCAD found several gaps. This is actually a problem with screen resolution and not my geometry. Watch this. I am going to type re to regen the drawing and then we'll try the boundary again. Let's launch Boundary and I'll click inside the shape one more time. Now that AutoCAD has successfully found the boundary, I'll press Enter and then I'll double-click my scroll wheel to do Zoom Extents. At this point I'd like to isolate my area layer such that we can visually see the areas where we will be installing sod.
To do that, I'll open the Layer Properties Manager. I will select the area layer and then I'll right-click and I'll choose Invert Selection and then I'll click one of these lightbulbs. This will turn all of the other layers off. Now to find the total area of all of these shapes, I'm going to convert them into regions. To do that, I'll open the Draw panel. I'll launch the Region command. I'll select the four shapes and I'll press Enter. If you look at the command line you can see four regions created.
Now the reason I wanted to convert these into regions is because regions can be joined together using the Union command. I am going to type Union and I'll press Enter, and then I will select these four shapes again and press Enter. Now if I hover over this edge, you can see that AutoCAD treats these objects as a single region. If I select this region, I can come over to the full Properties palette and I can find the area right here. I know that because my drawing units are set to feet.
Remember we wanted square yards. So I'm going to click inside this cell and then I'll click the Calculator icon. Now my calculator is coming up in the expanded state. If yours is not, you may have to click this More Than button to see all the controls. I am going to grab this slider and I'll pull down. In the Units Conversion area, under Units type, I am going to set this to Area, Convert from, Square Feet, I would like to convert this to Square Yards.
Now it would have been nice if AutoCAD would have dropped this value down there for me. To move the value I'm going to double- click in the Expression area and then I'll click in the Value to Convert area, and I can see the converted value right here, approximately 4582 square yards of sod. Let's close this. I no longer need my region. Since it's selected, I'll press the Delete key to erase it. To put my layers back the way they were, I am going to go back to the Layer Properties Manager.
Notice that AutoCAD remembers my previous selection. I'll click any of these lightbulbs to turn those layers back on. So the next time you need to calculate the area of several shapes, try converting the shapes into regions first and then union them together. AutoCAD will do all the math for you and if necessary, it will even convert the value to any unit of measure you need.
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