Seeking help regarding the differences between the three spaces in CAD

Model space is the area where drawing is usually done; the other two spaces are basically useless. Drawing space is primarily used to view the layout of the drawing as well as its linear proportions. There isn’t much difference between model space, where the viewport is active, and drawing space; in my opinion, one option keeps the dimensions of the drawing constant while the drawing itself changes when zoomed in, while in the other option both the drawing and the graphics scale together when zoomed in.

Simply put, model space is the space where you draw content related to solid objects; it is used for modeling； Layouts (referred to as paper spaces in versions prior to R14; a file can have only one paper space, while versions of AutoCAD 2000 and later allow multiple layouts per file) are used to arrange and print content, functioning similarly to page settings in Office. Generally, one layout is used for each printed sheet (although there are also layouts designed for multiple sheets, this practice is not recommended). The size of the drawings in the layout is the same as the size they will have when printed, such as A1, A2, etc. To print all or part of the content in the model space, it is necessary to set an appropriate scale for the viewports in the layout (which are used to view and print the content in the model space), so that the objects in the model space are printed on the paper at the correct size. It can be seen that, regarding the layout, the printing scale is 1:1 by default (of course it can also be printed at a certain scale, but this is not usually done). The output scale is reflected in the viewport, which functions somewhat like the focusing mechanism of a telescope. Since the layout itself is printed at a 1:1 scale, there is no need to consider the printing scale when placing labels, explanatory text, etc. within the layout, which thus simplifies the printing process ； The floating model space (which is entering model space within a layout) allows tasks to be performed in model space, but its main purpose is not that; rather, it serves the following functions: 1. Adjusting the display position of objects in model space within the viewport (through dragging, command adjustments, etc.). 2. Change the view direction of the model object (mainly used in 3D). 3. Control the freezing and thawing of layers in the current viewport (to facilitate effective output control). 4. Extract the contour lines of the 3D objects to obtain the intersection lines (which can also be regarded as axonometric views). Perhaps there are others... Every feature in AutoCAD should be useful, not useless! If you think it’s useless, that just means you don’t know it well enough yet. Of course, as a user, it is quite difficult and unnecessary to master all functions.

Thank you, Senior Tian Gong Kai Wu, because I usually work with 2D plans; I have no experience with 3D models and don’t know how to create them. I cannot understand the benefits of 3D applications that you mentioned. But for the others, it’s basically as you said. Additionally, 1. Is the CHSPACE command applied only to the switching between the floating model space and paper space? 2. After dimensions are marked in paper space, how can these dimensions be linked to the graphics, so that when the position of the graphics in model space is changed or their scale is adjusted in the model space view, the dimensions will automatically adjust accordingly. I have a question!

1. The CHSPACE command is used to transfer objects between paper space and model space; it must be used in a layout, not in model space. But if an object in the layout is transformed to model space, it becomes like other objects in model space. However, this command is not used very often. 2. The system variable dimassoc controls the association of annotations; setting it to 2 connects one or more definition points of the annotation to the associated points on the geometric object. Teacher Chen Boxiong, an authority on AutoCAD, is a proponent of placing dimensions in the layout space, as this eliminates the need to worry about the printing scale. However, in AutoCAD 2008, the introduction of annotative scales simplified all issues related to the drawing scale, allowing problems associated with it to be resolved easily even when dimensions are placed in model space. Moreover, annotations placed in the model space can be used in layouts with various viewport scales; therefore, I recommend versions from 2008 onward, as it is better to keep annotations in the model space.

You are so strong! 1. CHSPACE is used mainly in situations where the drawing is created in the model space, while annotations and notes are placed in the paper space. If it is necessary to copy both the drawing along with its annotations and notes to another drawing, CHSPACE must be used to transfer those annotations and notes from the paper space back to the model space. I only know this solution; are there any other ways? 2. The articles I read usually also include annotations in the layout and diagrams within the models, and that’s how I learned to apply it as well. Teacher Chen Boxiong is a proponent of placing annotations in the layout space. I must have read some of Teacher Chen Boxiong’s posts before, as I remember the username \"Chen Boxiong\". Could you provide me with a link to his articles so that I can study them carefully? Because I have been using 2006 so far and have not had any experience with 2008. I still can’t understand the labeling scheme you mentioned for 2008. I’ll wait until I have the chance to upgrade to 2008 and then consider your reply. Thank you again. I have another question for you: for example, in my layout there are two viewports, and the objects in both viewports are either objects in model space; or one viewport shows the entire object while the other shows only a part of it. How can I set the print line width to ensure two different thicknesses, for example, thick lines for one viewport and thin lines for another?

It can be resolved through AutoCAD Central. See: http://bbs.hcbbs.com/viewthread.php?tid=323364&page=1#pid1631400