Spherical lithophane

prusaprinters

<p><strong>2018-03-02 There is a new implementation of <a href="https://www.thingiverse.com/thing:2811616">this object</a>.</strong></p> <p>This is a python script to map a grayscale image as a height map onto the inside of a hollow sphere. The result is a spherical lithophane with a smooth outside.</p> <h3>Print Settings</h3> <p><strong>Printer Brand:</strong></p> <p>Wanhao</p> <p><strong>Printer:</strong></p> <p>Wanhao Duplicator i3 V2</p> <p><strong>Rafts:</strong></p> <p>Yes</p> <p><strong>Supports:</strong></p> <p>Yes</p> <p><strong>Resolution:</strong></p> <p>0.1mm layer 0.4mm nozzle</p> <p><strong>Infill:</strong></p> <p>100%</p> <p><strong>Notes:</strong></p> <ul> <li>since the globe is quite small at the bottom I chose to use rafts for my first print - it would be a shame if anything fell over after 30 hours of printingrn+ you don't want to see any fill pattern shine through the walls and the whole concept of a lithophane depends on a solid wallrn+ on the other hand don't forget that the globe itself is hollow - the 100% infill only affects the wall of the globe</li> </ul> <h3>How I Designed This</h3> <p><strong>Original idea</strong></p> <p>A couple of days ago I saw the YouTube video where<em>RCLifeOn</em> presented his <a href="https://youtu.be/YjkP1BcwLNI">spherical lithophane globe</a>. He used Autodesk 3ds Max to design the object, where he placed the height map on the outside of the globe, but I immediately wondered how it would look like when the height map was hidden inside the globe.rnrnI din't see before now that RCLifeOn also posted his globe here on <a href="https://www.thingiverse.com/thing:2761284">Thingiverse</a>.rn</p> <p><strong>Free and open source?</strong></p> <p>Not having access to this piece of software I researched if I could get a similar result using free tools. My favorite OpenSCAD does not (yet?) support mapping of bitmap files onto non-flat surfaces, so I had to look further.rnrnI quickly found an example on how to create an .stl file in python and started to experiment. My first output was a simple cube, before I put all pieces together:rn+ scaling an imagern+ creating a spherern+ creating a second spherern+ putting the two spheres into each otherrn+ modifying the thickness of the wall by means of the map</p> <p><strong>It works</strong></p> <p>Once I got the orientation of the faces correct and also succeeded in putting the image data the correct way onto the spheres, I let my script run for an hour or so and created the mesh for a 120 mm diameter globe, which has now been on the printer for 24 hours with about 10 hours left to go according to Octoprint.rnrnThe map I use is the free <a href="https://asterweb.jpl.nasa.gov/gdem.asp">height map image of the world</a> by NASA.rnrnI then took the time to fine tune the script a bit and add some comments for readability.</p> <p><strong>User parameters</strong></p> <h3>user settingsrn dia = 120rn depth = 3rn wall = 0.8rn latsteps = 600rn longsteps = 1200rn openingNdeg = 20 # opening x degrees from north pole rn openingSdeg = 130 # opening x degrees from south polernrn+<em>dia</em> is the diameter of the final globe in mmrn+<em>depth</em> is the maximum variation of the thickness of the globe's wallrn+<em>wall</em> is the minimum remaining thickness of the wallrn+<em>latsteps</em> is the number of steps from north to southrn+<em>longsteps</em> is the number of steps along the equator rn+<em>openingNdeg</em> is the size of an optional opening at the north polern+<em>openingSdeg</em> is the size of an optional opening at the south polernrnThe above example settings produce a narrow rim of the globe between 40u00b0N (=-90+130) and 70u00b0N (=90-20) for testing purposes.</h3> <p><strong>pre-rendered .stl files</strong></p> <p>*<em>lithophane_world_closed.stl</em> complete world, 120mm diameter, no holes, 300 latitude steps, 600 longitude stepsrn+<em>lithophane_sphere_outside</em> low-resolution, mapped on the outside of the sphere</p> <p><strong>Work in progress</strong></p> <ul> <li>2018-01-24 started printingrn+ 2018-01-25 still printing while writing this Thingrn+ 2018-01-26 also uploaded a script to generate the map on the outside of the sphere</li> </ul> Category: Sculptures