Delve into the nuanced differences between annotation objects like text, dimensions, and drafting symbols and real-world objects like walls, doors, and window geometry in AutoCAD. This article clarifies the varying scales at which these objects are drawn, and how this relationship has evolved over time.
Key Insights
- The article explains how real-world objects like walls, doors, and windows are drawn at a real-world scale while annotation objects such as text and drafting symbols are drawn at a paper scale in AutoCAD.
- Historically, real-world objects and symbols were drawn at the same time on paper, using pencil or pen. However, in AutoCAD, while symbols are still drawn at their paper size, real-world objects are drawn at a real-world size, thus changing this relationship.
- The scaling relationship between model space and paper space, and drawing scale per object or per block is explored in depth. The piece also clarifies how the scale of a block or an object can be increased by a scale factor in order to fit onto a piece of paper while maintaining the real-world representation.
Note: These materials offer prospective students a preview of how our classes are structured. Students enrolled in this course will receive access to the full set of materials, including video lectures, project-based assignments, and instructor feedback.
In this video, I want to look at the differences between annotation objects like text, dimensions, and our drafting symbols, and real-world objects like our walls, doors, and window geometry. These geometries are drawn in AutoCAD at different scales.
It makes sense that our real-world geometry would be drawn at a real-world scale, and it would make sense that our annotation objects would be drawn at a paper scale. But what does that really mean, and how has that changed over time? As you can see, we are looking at the final product for this course, which is an 8.5 × 11 sheet of paper with a title block, our real-world geometry like our walls, doors, windows, and fixtures, and our annotation objects like our dimensions, text, and our drafting symbols like our door symbols. Or here is our detail hat and our detail symbol, which when used together represent a wall section or a detail section.
These objects have historically been drawn at the same time on sheets of paper by hand with either pencil or pen and rulers and straight edges. This was a challenge because it meant that when we drew real-world geometry, we could not draw it at a real-world size. Instead, we would scale the model down to fit it on the piece of paper.
But on every sheet that we drew, the symbols were drawn at a real-world size. That is, if a symbol was a half-inch diameter, we would draw it with a half-inch circle template with our pen or pencil. In AutoCAD, that relationship has changed.
We still draw our symbols at their paper size, half-inch, quarter-inch, or similar, but we also draw our real-world objects at a real-world size. This means that this wall at the top of the building is 24 feet long. And this is the relationship between model space and paper space and drawing scale per object or per block.
So let's look at that in model space for a second. Here I am in my model space environment, and this is where our real-world geometry is drawn. If I zoom in, this line segment is 24 feet long.
It is not a visual representation that is drawn shorter to fit on a piece of paper. It is drawn at the real-world scale. This symbol, however, is drawn at a smaller scale, the paper scale.
But if I select it, right-click Properties, I can see that the scale of this block or this object is not set to scale 1. This is because the object has been increased by a scale factor of 48 to visually represent how this would look in paper space on our 8.5 × 11 sheet of paper. Remember, historically, we've had to scale down our buildings and scale down our drawings in order to fit on a piece of paper. In this situation, we are doing two steps.
We first scale up our paper space objects when they are inserted into model space, and then using a viewport, which we'll discuss later in this course, those objects and our real-world geometry are scaled down to fit on a piece of paper. Now, what does the 48 scale factor mean? Well, we can see here our drawing scale is one quarter inch equals a foot, and if I double-click in this viewport again, which we'll talk about later, I can see down here in the bottom right that it also reads one quarter inch equals a foot. This means that in order for our scales to match, our paper space objects need to be scaled up so that the equation is one equals one.
But when we have one quarter inch, we need to do four to equal one inch times 12, which equals 48, and so we have to scale up our symbols 48 times because our viewport is scaling down the drawing 48 times. Now, this might be confusing. Hopefully, it will make more sense as we move forward in the course, but that is the difference between our drawing tiny little symbols at the beginning of the course versus our real-world drawings at the end of the course.
In the end, these two pieces come together to create one construction document or construction document set.
