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It's important to remember that even though you may be creating a 2D drawing, AutoCAD is a 3D environment. All it takes is a couple of skewed Z coordinates and you may be constructing geometry at several different elevations without even knowing it. In this lesson we're going to learn how to flatten a drawing whose elevations may have gotten out of control. On my screen I have a drawing of a site plan for a proposed park and I'd like to start by taking a measurement. Let's zoom in and we'll find out how far the sidewalk is from the back of curb.
I'll launch the Distance command and I'll use the Nearest object snip. Let's find the distance from nearest to here to a point perpendicular to the curb. Notice that my distance is slightly more than 278 feet. I am going to press Escape. Now that distance can't possibly be right. Or can it? You see, I am looking at this drawing with a 2D mindset. What if some of this geometry was drawn to an elevation? Let's take a look.
I am going to double-click my scroll wheel to do a Zoom Extents and then I am going to come over to the view cube and I'll select a southeast isometric view. All right, now this is a problem. As you can see several of the objects have been drawn or inserted at multiple elevations. Now how does something like this happen? Well, if you exchange drawings with someone who typically works in 3D, something like this can happen very easily, because from a top view you can't see the elevations. So it's very easy to assume that everything is being constructed flat on the coordinate system.
You know as a side point, the next time you get a chance open some project drawings that you've worked on with other clients and take a look at them from a southeast isometric view. You might just be surprised at what you see. All right, so how do we fix something like this? Well, I am going to go back to the top view. Let's zoom in. Right now all of the X and Y coordinates of this geometry are good. If we could just set all of the Z coordinate values to 0, we could flatten the drawing. Fortunately there is a tool that will do this for us automatically.
However, it does have one catch. It doesn't work well with blocks, and in this drawing all of my trees are blocks. So I'm going to move up and launch the Layer Freeze command and I'll select one of my trees to freeze that layer, and I'll press Escape. All right the command we will use to fix this, as on the Express Tools tab. I am going to open up the Modify panel and we'll use this command, Flatten Objects. I am going to zoom out.
I'll select this geometry and press Enter. Now AutoCAD is asking me to remove hidden lines. A hidden line would be a line that's obscured from view and in this case I'm going to press Enter and accept No because I don't want AutoCAD to delete anything. And after a couple seconds, AutoCAD converts the geometry and if I adjust my view again, let's go back to a southeast isometric view. In fact let's go to a right side view. You can see this geometry has been completely flattened. Now how do we deal with the tree blocks? Well, I am going to go back to the Home tab.
Let's click Layer Previous to turn that layer back on and let's set this back to a southeast isometric view. I'm going to fix these trees manually using the Properties palette. I'll start by selecting the symbols. Then I'll come over to the Properties Palette and I'm going to change their Z coordinate to 0 and I'll press Enter. When I'm finished I'll press Escape to deselect. All of my geometries now have been flattened and I'll restore a top view.
So even if you consider yourself a 2D drafter it's important to remember that your drawings might have some 3D geometry. In the event you discover some line work with unnecessary elevations, you can quickly set the elevations back to 0 using the Flatten command.
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