What kind of data in CAD drawings is redundant and can be removed?

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When using the HaoChen CAD drawing software to create drawings, sometimes not many graphics are added to the drawing, yet the size of the drawing file increases significantly, and opening, saving, and editing the drawing become increasingly slow. At this point, it is necessary to clean up the CAD drawings. So, what kind of data is redundant and can be removed? Simply put, data that is defined but not used in the diagram is data that can be cleaned up. Formats such as layers, dimension styles, and text styles are generally easy to understand. For example, when we use a template file or professional software, a new drawing may contain several or even dozens of layers as well as many dimension styles; however, only some of them are used in the actual drawing, and the unused layers and dimension styles can be removed. However, these data take up little space; unless there is an abnormally large amount of them, they can be ignored during cleanup. Among the data that can be cleaned, blocks usually take up the most space. Since many people think that once a block is deleted or exploded, it no longer exists, quite a few people define numerous graphics as blocks or copy and paste them as blocks for the sake of easy insertion and positioning; after positioning them, they explode them for further editing. This method of operation causes graphic files to grow rapidly, as such blocks often contain many graphics, and sometimes even an entire drawing. After the block is exploded, it does not disappear; you can insert this block at any time by using the Insert (I) command. We must remember that once a block is defined, a block definition is saved in the drawing; what we see when it is inserted into the drawing is called a \"block reference\", which means that the block definition has been referenced once. The advantage of doing this is that the size of the drawing file does not increase significantly when the same block is inserted multiple times in the diagram. Once a block is defined, as long as it has not been deleted, whether it is inserted, exploded, or modified in the diagram, the block definition remains intact! On some drawings, a long list of blocks can be seen in the cleanup dialog box; after removing those blocks, the size of the drawing file is reduced to a fraction of its original size. By maintaining good habits and avoiding arbitrary definition of blocks or copying/pasting content as blocks, there will be fewer unnecessary blocks, and the size of the drawings will not increase significantly. As zero-length graphics and empty text objects appeared frequently in older versions of drawings, HaoChen CAD later added such an option to the cleanup dialog box. In earlier versions of HaoChen CAD, if the multi-line text command is used and no text is entered before confirming the operation, an empty text object is created; this problem no longer exists in newer versions. Zero-length graphics and empty text objects may also be generated by certain plugins or software. I’ve encountered this before, but not very often. If you find this option activated while cleaning up, just check it. These common redundant data in CAD drawings are not a problem and are easy to handle. Some articles on public accounts have mentioned special types of data, such as isolated DGN line styles, annotative scales, layer filters, etc., and CAD is gradually providing corresponding functions to deal with them. The most troublesome among them are DGN line data; once graphics are copied and pasted from other drawings, they multiply when copied and pasted into this drawing. This not only severely affects the size of the drawing and its operational performance, but may also prevent copying and pasting from working. Since there are many such drawings, the cleanup PU dialog box in newer versions of CAD software provides an option for removing isolated graphic data. If a lower version of CAD software is used, one can only use LISP commands to delete such data; copy the code below into the CAD command line and press Enter – any DGN data present will be deleted. (dictremove(namedobjdict) “ACAD_DGNLINESTYLECOMP”). As for the large number of annotation scales and layer filters, they cannot be cleaned using the PU cleanup function; in newer versions, a prompt will appear when opening a drawing or the layer manager, asking whether reset and cleanup are needed. If we are using an older version that does not provide such a feature, we can try selecting everything, copying it, and pasting it into a new drawing, or use WBLOCK (W) to save it as a block file in order to clean it up. The main reasons for the generation of redundant data are as follows: 1. Generated by specialized software or plugins. 2. Copied and pasted from other diagrams. 3. Not very good drawing *habits. If, when creating drawings on a regular basis, we pay attention to the types of redundant data in our drawings and their sources, thereby reducing the likelihood of such redundancy from occurring in the first place, then there will be no need for cleanup. We need to be careful and ensure that there is indeed a significant amount of redundant data in the image before proceeding with cleanup. It’s best to take a look first rather than simply clicking ‘Clear All’. If you haven’t finished drawing your graphic, there may be certain layers, text styles, annotation styles, blocks, and loaded line types that will be used later; if they are deleted, they will need to be defined or loaded again. The above covers the types of data in CAD drawings that are redundant and can be removed when using the HaoChen CAD drawing software. I hope this will be helpful to everyone!