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    Geosphere?

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    • pilouP Offline
      pilou
      last edited by

      A sphere with a center (x0,y0,z0) with diameter r
      has all points x,y,z like

      http://upload.wikimedia.org/math/3/3/0/33031c82e871501422b05455c81d2680.png

      with

      http://upload.wikimedia.org/math/e/b/9/eb91f8174391d023015dedf9beb94e5d.png

      http://upload.wikimedia.org/math/9/0/1/9011474548ae3216019a280ff95d25a3.png
      = Latitude

      http://upload.wikimedia.org/math/1/9/6/1964adc54d7dc608fd9f63a46cae422b.png
      = longitude

      Frenchy Pilou
      Is beautiful that please without concept!
      My Little site :)

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      • thomthomT Offline
        thomthom
        last edited by

        Isn't that a sphere with poles? The points would not be evenly spaced.

        sphere.png
        I'm looking to generate the points for the sphere on the right.

        Thomas Thomassen β€” SketchUp Monkey & Coding addict
        List of my plugins and link to the CookieWare fund

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        • T Offline
          tml
          last edited by

          @thomthom said:

          I'm looking to generate the points for the sphere on the right.

          Start with a octahedron, divide each edge into half and thus each face into four equal smaller triangles, move the new vertices to the desired radius, repeat.

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          • T Offline
            tml
            last edited by

            Note that the above results in just a fairly nice approximation, though. (And I don't know if it matches the subdivision used in your example image.) Only for the (not really sphere-like, as they have so few faces) Platonic solids are the vertices in a strict sense evenly distributed, though. See http://www.cgafaq.info/wiki/Evenly_distributed_points_on_sphere and especially http://www.math.niu.edu/~rusin/known-math/95/sphere.faq .

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            • thomthomT Offline
              thomthom
              last edited by

              Approximation is ok. Just just want to take a fixed number of points and distribute them approximately evenly. Doesn't matter if they need to be rounded to a number that fit some geometric restriction.

              Thanks for the links - I'll look into them.

              Thomas Thomassen β€” SketchUp Monkey & Coding addict
              List of my plugins and link to the CookieWare fund

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              • thomthomT Offline
                thomthom
                last edited by

                Excellent - the spiral methods works great for my use! πŸ‘

                Thomas Thomassen β€” SketchUp Monkey & Coding addict
                List of my plugins and link to the CookieWare fund

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                • AdamBA Offline
                  AdamB
                  last edited by

                  Its pretty common to subdivide a cube and then project onto a sphere.

                  If you want evenly distributed but not a regular mesh, you could use a Hammersley point set.

                  Developer of LightUp Click for website

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                  • thomthomT Offline
                    thomthom
                    last edited by

                    @adamb said:

                    Its pretty common to subdivide a cube and then project onto a sphere.

                    Would that give a even-ish distribution?

                    @adamb said:

                    If you want evenly distributed but not a regular mesh, you could use a Hammersley point set.

                    Thanks for the pointer - will look it up. πŸ‘

                    Thomas Thomassen β€” SketchUp Monkey & Coding addict
                    List of my plugins and link to the CookieWare fund

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                    • david_hD Offline
                      david_h
                      last edited by

                      @unknownuser said:

                      A sphere with a center (x0,y0,z0) with diameter r
                      has all points x,y,z like

                      http://upload.wikimedia.org/math/3/3/0/33031c82e871501422b05455c81d2680.png

                      with

                      http://upload.wikimedia.org/math/e/b/9/eb91f8174391d023015dedf9beb94e5d.png

                      http://upload.wikimedia.org/math/9/0/1/9011474548ae3216019a280ff95d25a3.png
                      = Latitude

                      http://upload.wikimedia.org/math/1/9/6/1964adc54d7dc608fd9f63a46cae422b.png
                      = longitude

                      That is just how I would do it! πŸ˜’ πŸ’š

                      If I make it look easy...It is probably easy

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                      • pilouP Offline
                        pilou
                        last edited by

                        Me too πŸ˜„

                        Frenchy Pilou
                        Is beautiful that please without concept!
                        My Little site :)

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                        • thomthomT Offline
                          thomthom
                          last edited by

                          Google are really quick to index this site!
                          I did a search for "Hammersley point set sphere" and this thread came up as #3 already. πŸ˜’

                          Thomas Thomassen β€” SketchUp Monkey & Coding addict
                          List of my plugins and link to the CookieWare fund

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                          • mitcorbM Offline
                            mitcorb
                            last edited by

                            Not busy enough elsewhere, eh tml?
                            Thank you for your talents, also.

                            I take the slow, deliberate approach in my aimless wandering.

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                            • AdamBA Offline
                              AdamB
                              last edited by

                              There you go.

                              http://forums.sketchucation.com/viewtopic.php?f=180&t=30694&p=269864#p269864

                              Developer of LightUp Click for website

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