Part 2
Module 9: Controlling the Drawing
Learning Outcomes
When you have completed this module, you will be able to:
- Describe the drawing terms; limits, extents, scale, units, and regeneration.
- Apply the ZOOM, PAN, REGEN, and VIEWRES commands and explain how you use them to control the drawing.
Controlling the Drawing
To control the drawing and improve your drawing speed, it is important for you to understand the drawing terms; limits, extents, scale, units, and regeneration and how they relate to the current drawing.
Drawing Limits
An AutoCAD drawing has an unlimited amount of model space available to draw in. The drawing limits are a user defined rectangular or square shape of 2D model space. The size of the drawing limits can be changed, as required, at anytime.
Drawing limits were important before layouts were added to AutoCAD in AutoCAD 2000. They are not that important to AutoCAD 2000 and newer users but are still part of the software.
Drawing Extents
The drawing extents is defined as the smallest rectangle that will fit around all existing drawing objects in the current drawing that are visible (on a thawed layer). It is possible to draw outside the drawing limits and therefore objects that are outside the limits may not be visible in the normal drawing display. By being able to display the drawing extents, all visible (thawed) drawing objects that exist in the current drawing will display in the Graphic window. Being able to display the drawing extents is very important.
Since Model space is very large, objects are sometimes placed, by accident, somewhere out in space. If this happens in a drawing, it can severely derogate the performance of the drawing. Sometimes the only way to work on a drawing that is derogated is to find the erroneous objects and delete them. They can easily be found by displaying the drawing extents.
Drawing Scale
The general rule for all AutoCAD drawings is to always draw the object at full scale or full size. Scaling is done in the viewports in the layouts. This is taught in Module 18.
Drawing Units
AutoCAD drawings are unitless. If a unit of 1 is entered into a drawing and the units selected by the creator for that drawing are inches, then 1 means 1 inch. From that point forward all units entered into that drawing must be entered as inches. In another drawing, the operator creating the drawing picks the units to be millimeters. All numbers entered in that drawing must be entered in millimeters.
To sum up, when a drawing is first started, the creator must make a decision as to what units will be used for that drawing. From that point on, all numbers entered into that drawing must be entered in those units.
Zooming
Zooming is the process of moving the drawing objects closer or further away from your eyes without actually changing the size of the objects or their location in model or paper space. It is an important tool for you and is used extensively in the drawing process. Drawings can be very large and theref