IntroductionWe routinely get inquiries as to whether we can offer a DXF or DWG to BMP/TIFF rasterizer for mask or image writers. The answer is: NO. Why not? We could easily do it. But our 25 years of experience tells us this is a bad way to go. Here's why. |
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AutoCAD (and we'll let AutoCAD be a proxy for all mechanical drafting programs) is not intended to produce clean and correct data for mask making. At its most basic, the user merely lays down lines and arcs. Now a user is free to create a boundary to be filled but these lines and arcs are not necessarily associated with each other unless the user takes advantage of AutoCAD's polyline. Many drawings will be produced where additional postprocessing is needed to convert lines and arcs into boundary regions that can be defined as "dark" or filled. Unfortunately, the free form nature of the drawing tools allows the user to make many mistakes; so any program that automatically converts these lines and arcs into boundaries is likely to also produce output that was not intended due to these drafting mistakes. |
Further there is a problem of "intent." When drawing complicated structures with holes or islands there are different ways to implement these holes. Any conversion program has to understand the user's intent and that is quite difficult to do reliably. Take a circle for example. Does the user intend that the circle be completely filled solid? Or should the program create a ring? If so, of what width? Since the user doesn't see a preview of the mask he won't know how that circle will appear in the output. It is issues like this that make direct rasterization unlikely to produce the desired mask and which introduce so many technical support issues that we simply refuse to offer a direct RIP. Instead we recommend that the DXF be converted into a reliable mask format such as Gerber (RS274X). This enables the designer to view the Gerber and preview his mask. If there are any discrepancies they can be identified and corrected so that the Gerber accurately represents the intent of the mask. |
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We've produced a 3 part video that explains this and takes you through the DXF to Gerber conversion process and subsequent RIP. While it may seem ideal to go directly from DXF/DWG directly to a bitmap, our experience has been that such a path leads to a very large number of mask errors .Why We Don't Rasterize DWG/DXF Directly Part I Why We Don't Rasterize DWG/DXF Directly Part II |