Stereographic Projection

thingiverse

I had fun with this one, for other examples of people doing Stereographic Projection, I highly recommend https://www.thingiverse.com/threonin/. His stuff is amazing and I love it. This is a writeup of how to use this OpenSCAD design using dxf files. * I have only tested this on a square pattern, but there's no reason it has to be square, it could be rectangular or circular as well. ###Instructions### <ol> <li>Find a black and white* pattern that you want to vectorize. Its easier if there aren't many grays. This step is skippable if you already have a monochrome vector pattern. <ul> <li>I just googled "black and white pattern".</li> <li>Save the pattern to your computer.</li> </ul></li> <li>Inkscape Directions <ol> <li>Open a new file in Inkscape (0.92) and *import* the imagefile. Don't 'Open', it can crash Inkscape. (png is good, jpeg is less good) </li> <li>Use the Menu -> Path -> Trace Bitmap tool. <ol> <li>Make sure the image is selected or the tool wont work.</li> <li>I used the "Brightness Cutoff" option, Threshold: 0.45, You will want to play with these options to see what works best for your pattern.</li> <li>The new pattern is dropped ontop of, or underneath the original image, so you need to drag it off the imported bitmap image.</li> <li>You can tell which is which by typing F2 to select the edit pathnodes tool. The one with paths is the one you want. Delete the other one.</li> <li>Next we need to break up the paths into small pieces with the Menu -> Extensions -> Modify Path -> Flatten Beziers.</li> <li>This breaks the curved lines up into bite-sized pieces because OpenSCAD does not like dxf splines. If you have curves, this step is not optional.</li> <li>The smaller the "Flatness" variable, the more segments, so I used '0.1'. If you pick numbers greater than 1, you're likely to see chunky, rather than smooth shapes.</li> <li>Verify it by hitting F2 again, and then save the file to svg. (thats Inkscape's native format)</li> <li>Resize the Page by Menu -> File -> Document Properties <ol> <li>Its important to have a page size that fully encompasses the pattern. Inkscape will cut off things that aren't on the page.</li> <li>I sized the page to exactly the size of the pattern, in px.</li> <li>Then I used the Menu -> Object -> Transform tool to (uncheck 'Relative') Move it exactly to (0,0)</li> </ol> </li> <li>You can check the Layer name from Menu -> Layer -> Layers... For my scad-file you want it to be "Layer 1". </li> <li>Then SaveAs filetype .dxf</li> <li>Once you click OK, it will ask you about how you want to save it, Uncheck the ROBO-Master option, and Check the LWPOLYLINE option. I left it defaulted to base unit of pt, but using mm makes sense too.</li> </ol> </li> </ol> </li> <li>OpenSCAD <ol> <li>When importing, OpenSCAD reads from the same directory that the scad file is in, but you can also use a full filepath. I was impatient, so my example assumes the dxf is sitting in the same directory as it.</li> <li>Its very helpful to know the size of the original image.</li> <li>I left helpful comments in the code to show you which variables to modify with what information.</li> </ol> </li> </ol> Feel free to take out the Support Legs, if they are a bad fit for your pattern. Also, this took literally 35 minutes to compile the stl, so be prepared.