![]() ![]() Practical sketches seem to have a lot of such structure, and a visualization of that graph would be an interesting expression of the design intent. The difficulty is mostly in writing them, to handle many useful cases in relatively few lines of code, and to converge reasonably in the Newton's method.įor a dramatic speedup, we could partition the constraint equations into roughly-triangular form, and then solve sub-systems in dependency order. The Jacobian matrix is computed by an internal symbolic algebra system, allowing considerable flexibility in the range of user-facing constraints without a combinatorial explosion of hand-coded special cases.Īs whitequark notes, the final solution of the constraint equations is a relatively small part of the overall work. They're solved by a Newton-ish method, which for underconstrained sketches also minimizes at each step the sum of the squares of the distances that any un-dragged points move (plus some other stuff). So yeah, the constraints in SolveSpace are nonlinear. An optimized matrix library (Eigen, BLAS, LAPACK, etc.) would provide a modest speedup without too much work. This is of the local area of Redditch so the Cubs could also associate it with the places they know."Constraint" means something different to Cassowary than it does to us here, and isn't obviously useful. Depending upon the size of your model and the bed size of your 3D printer you may have to scale the model in the slicer so that it can be 3D printed.įor one of the models I printed it on white PLA and then using a sharpie I added some of the map symbols to help show how the map and the 3D model related to each other. Once it's complete then it can be exported as an STL file which can viewed through a 3D viewer or imported to your slicer software for 3D printing. I cleaned up the edges by cutting away any excess using tools in the FreeCAD part workbench. This was repeated with a new body, sketch and pad for each contour layer. The resulting sketch could then be extruded into a 3D object using the pad tool. This is achieved by clicking onto the contour line at regular intervals, zooming in and scrolling around the FreeCAD model as required. I then created a body for each layer and created a sketch mapping out one of the contour lines using the b-spline tool. This makes it easier to determine the correct value when using the pad. ![]() In my case I set a scale of 1mm to 1 meter. If you include the map scale on the map then you can set the scale using the scale tool. The map is first imported to FreeCAD using the Images Workbench. They also provide a premium account which provides additional maps, if you wanted more detail. OS Maps provide a free "standard" level map which is available through a free account. You can use alternative maps (including Google Maps). Ordnance Survey are the national mapping country for Great Britain and the standard for walking maps. The example map used in the video is an Ordnance Survey Map, known as OS Maps. This could also be a useful technique if you would like to visualize a hill before your walk or to create 3D models of places you have visited. This helped them to visualise the contours so that they could understand how steep a hill is by looking at a map. I used this to help teach map and navigation skills to Cub Scouts. The model can then be printed using a 3D printer, or viewed online as a static image or through a 3D viewer. This is a manual process in mapping the contour lines from an OS map into FreeCAD. In the video below I show how you can take a 2D map and create a 3D model using FreeCAD.
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