Marking the start of this article with a question why 2D to 3D conversion? For this we need to go through the history of drafting. Ever since the beginning of scientific era, engineers used drawing as a medium of communication.
Engineering drawing emerged as a discipline of technical communication employing distinct line types such as solid lines, dashed lines, hatching lines, cutting plane lines, centre lines etc to draw orthographic views of a product. Later with the development in computing, manual drafting shifted to 2D modelling. 2D modelling used the same concept of manual drafting but drawing was shifted from paper to computer screen. In this way 2D or orthographic drawings are a sort of legacy for us. Now the answer to the question marked at start,
- These legacy drawings are only understandable by technical persons and cannot be comprehended by a non-technical one, with 2D to 3D conversion it becomes comprehendible for any niche.
- 3D modelled drawing after rendering can serve as a picture of final product which can be used in catalogues and in marketing to non-technical personnel.
- 3D model can be used to check if the designed mechanism works according to requirements or not.
- 3D model enables you to study aerodynamics of design to check for drag and lift in case of planes and automobiles.
- Multiple pre-manufacturing analysis can be made on 3D models such as static structural analysis, thermal analysis, dynamic analysis etc. With these analyses you can check if the design is sustainable or not.
- The importance of 3D modelling has increased many folds due to advancement in machining, CNC machines require G-code to machine product in close tolerances. With a 3D model you can easily generate G-code using SolidWorks composer, Creo or any other software.
- 3D printing has also increased the importance of 3D modelling. A 3D printer requires a single .stl file to 3D print our model to physical state. Any 3D model can be converted to .stl file easily.
These multiple uses of 3D models have rendered the orthographic drawings as impracticable with modern practices, therefore 2D to 3D Conversion has become a necessity. Now moving towards the means to carry out 2D to 3D conversion. Different methods are used for 2D to 3D Conversion depending upon the drawing at hand.
If you have 2D files in .dwg format then 2D to 3D conversion is achieved easily because .dwg files are compatible with almost every cad software and its views can be imported as separate sketches and these sketches are employed to generate 3D model.
If you have a hardcopy of a drawing or a scanned image and the drawing is simple enough to be drawn such that it involves basic extrusion or revolve commands, it is modelled from scratch and 2D to 3D Conversion is achieved.
What if you have a orthographic drawing of a complex geometry composed of multiple surfaces such as a car or a plane’s profile, as shown in figure, and you need the profile to be accurate.
Almost every cad software has a provision to import image files, what you can do is to first scan the drawing and then divide the scanned image into multiple images each containing a single orthographic view and then you have to import these files in cad software. If you are using SolidWorks start a sketch on front plane and go to Tools>Sketch tools>Sketch picture, now select the picture with front view. Similarity add the pictures of top and side view. For back view, create a new plane, offset from front plane equal to the length of car as shown in figure.
Each CAD software has its unique interface and somehow the differences in names of certain commands also exist but the basic procedures remain the same. After having all the views at their respective planes, set the orientation as normal to any plane and trace any edge from the image, then again change the orientation making it normal to other plane and edit the traced curve such that it appears to be the same edge from the view selected. Similarly you have to edit the curve in accordance with the remaining views. After having drawn all the curves representing edges start creating surfaces from the curves. In this way a surface body will be generated same as the profile in the orthographic views. In this way 2D to 3D conversion is carried out in case of complex surface geometries.