How to calculate rectangle tangent to sphere












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Given a rectangle $ABCD,$ how do I calculate points $A, B, C, ; text{and}; D;$ if I place the rectangle tangent to a sphere, centered at a given Latitude and Longitude, and given a "Rotation" which would be degrees clockwise from "North" on the sphere?



You can assume that the sphere is a Unit Sphere centered at the Origin.
enter image description here



I'm trying include this in a software application, so I would appreciate solutions suitable for programming, i.e. algebra or trigonometry rather than calculus.



Thank you!










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    1












    $begingroup$


    Given a rectangle $ABCD,$ how do I calculate points $A, B, C, ; text{and}; D;$ if I place the rectangle tangent to a sphere, centered at a given Latitude and Longitude, and given a "Rotation" which would be degrees clockwise from "North" on the sphere?



    You can assume that the sphere is a Unit Sphere centered at the Origin.
    enter image description here



    I'm trying include this in a software application, so I would appreciate solutions suitable for programming, i.e. algebra or trigonometry rather than calculus.



    Thank you!










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      Given a rectangle $ABCD,$ how do I calculate points $A, B, C, ; text{and}; D;$ if I place the rectangle tangent to a sphere, centered at a given Latitude and Longitude, and given a "Rotation" which would be degrees clockwise from "North" on the sphere?



      You can assume that the sphere is a Unit Sphere centered at the Origin.
      enter image description here



      I'm trying include this in a software application, so I would appreciate solutions suitable for programming, i.e. algebra or trigonometry rather than calculus.



      Thank you!










      share|cite|improve this question











      $endgroup$




      Given a rectangle $ABCD,$ how do I calculate points $A, B, C, ; text{and}; D;$ if I place the rectangle tangent to a sphere, centered at a given Latitude and Longitude, and given a "Rotation" which would be degrees clockwise from "North" on the sphere?



      You can assume that the sphere is a Unit Sphere centered at the Origin.
      enter image description here



      I'm trying include this in a software application, so I would appreciate solutions suitable for programming, i.e. algebra or trigonometry rather than calculus.



      Thank you!







      geometry computational-geometry






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      edited Dec 11 '18 at 13:23









      user376343

      3,7883828




      3,7883828










      asked Dec 11 '18 at 12:57









      vocalionechovocalionecho

      91




      91






















          1 Answer
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          $begingroup$

          If you are aware of matrices, you can construct your rotation matrix from simple rotation matrices. Let's have rectangle parallel to plane $yz$ (with $z$ being the axis of spherical coordinates), sides parallel to $y$ and $z$ and center on the sphere (you can derive the coordinates of the vertices yourself).



          We first rotate rectangle around its central point (axis $x$) by angle $varphi$:
          $$
          Phi=begin{pmatrix}
          0 & 0 & 0 \
          0 & cosvarphi& -sinvarphi\
          0 & sinvarphi& phantom{-}cosvarphi
          end{pmatrix}.
          $$

          Then we rotate the rectangle by given latitude angle (around axis $y$):
          $$
          Theta=begin{pmatrix}
          phantom{-}costheta& 0& sintheta\
          0 & 0 & 0 \
          -sintheta& 0& cosvarphi
          end{pmatrix}.
          $$

          Finally, we will rotate around axis $z$ by longitude angle $lambda$:
          $$
          Lambda=begin{pmatrix}
          coslambda& -sinlambda&0\
          sinlambda& phantom{-}coslambda & 0\
          0 & 0 & 0 \
          end{pmatrix}.
          $$



          The total rotation is the product of the matrices. Since we apply matrices to vector from left to right, the order is like this:
          $$
          R = Lambda Theta Phi
          $$



          From programming point of view, you can either derive the final equation for the corners on paper and then write it in code. Or preferably, add multiplication by matrix as a function your code and apply matrix multiplication on demand. The latter case will give you more flexibility and is probably less prone to bugs.






          share|cite|improve this answer









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            1 Answer
            1






            active

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            active

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            0












            $begingroup$

            If you are aware of matrices, you can construct your rotation matrix from simple rotation matrices. Let's have rectangle parallel to plane $yz$ (with $z$ being the axis of spherical coordinates), sides parallel to $y$ and $z$ and center on the sphere (you can derive the coordinates of the vertices yourself).



            We first rotate rectangle around its central point (axis $x$) by angle $varphi$:
            $$
            Phi=begin{pmatrix}
            0 & 0 & 0 \
            0 & cosvarphi& -sinvarphi\
            0 & sinvarphi& phantom{-}cosvarphi
            end{pmatrix}.
            $$

            Then we rotate the rectangle by given latitude angle (around axis $y$):
            $$
            Theta=begin{pmatrix}
            phantom{-}costheta& 0& sintheta\
            0 & 0 & 0 \
            -sintheta& 0& cosvarphi
            end{pmatrix}.
            $$

            Finally, we will rotate around axis $z$ by longitude angle $lambda$:
            $$
            Lambda=begin{pmatrix}
            coslambda& -sinlambda&0\
            sinlambda& phantom{-}coslambda & 0\
            0 & 0 & 0 \
            end{pmatrix}.
            $$



            The total rotation is the product of the matrices. Since we apply matrices to vector from left to right, the order is like this:
            $$
            R = Lambda Theta Phi
            $$



            From programming point of view, you can either derive the final equation for the corners on paper and then write it in code. Or preferably, add multiplication by matrix as a function your code and apply matrix multiplication on demand. The latter case will give you more flexibility and is probably less prone to bugs.






            share|cite|improve this answer









            $endgroup$


















              0












              $begingroup$

              If you are aware of matrices, you can construct your rotation matrix from simple rotation matrices. Let's have rectangle parallel to plane $yz$ (with $z$ being the axis of spherical coordinates), sides parallel to $y$ and $z$ and center on the sphere (you can derive the coordinates of the vertices yourself).



              We first rotate rectangle around its central point (axis $x$) by angle $varphi$:
              $$
              Phi=begin{pmatrix}
              0 & 0 & 0 \
              0 & cosvarphi& -sinvarphi\
              0 & sinvarphi& phantom{-}cosvarphi
              end{pmatrix}.
              $$

              Then we rotate the rectangle by given latitude angle (around axis $y$):
              $$
              Theta=begin{pmatrix}
              phantom{-}costheta& 0& sintheta\
              0 & 0 & 0 \
              -sintheta& 0& cosvarphi
              end{pmatrix}.
              $$

              Finally, we will rotate around axis $z$ by longitude angle $lambda$:
              $$
              Lambda=begin{pmatrix}
              coslambda& -sinlambda&0\
              sinlambda& phantom{-}coslambda & 0\
              0 & 0 & 0 \
              end{pmatrix}.
              $$



              The total rotation is the product of the matrices. Since we apply matrices to vector from left to right, the order is like this:
              $$
              R = Lambda Theta Phi
              $$



              From programming point of view, you can either derive the final equation for the corners on paper and then write it in code. Or preferably, add multiplication by matrix as a function your code and apply matrix multiplication on demand. The latter case will give you more flexibility and is probably less prone to bugs.






              share|cite|improve this answer









              $endgroup$
















                0












                0








                0





                $begingroup$

                If you are aware of matrices, you can construct your rotation matrix from simple rotation matrices. Let's have rectangle parallel to plane $yz$ (with $z$ being the axis of spherical coordinates), sides parallel to $y$ and $z$ and center on the sphere (you can derive the coordinates of the vertices yourself).



                We first rotate rectangle around its central point (axis $x$) by angle $varphi$:
                $$
                Phi=begin{pmatrix}
                0 & 0 & 0 \
                0 & cosvarphi& -sinvarphi\
                0 & sinvarphi& phantom{-}cosvarphi
                end{pmatrix}.
                $$

                Then we rotate the rectangle by given latitude angle (around axis $y$):
                $$
                Theta=begin{pmatrix}
                phantom{-}costheta& 0& sintheta\
                0 & 0 & 0 \
                -sintheta& 0& cosvarphi
                end{pmatrix}.
                $$

                Finally, we will rotate around axis $z$ by longitude angle $lambda$:
                $$
                Lambda=begin{pmatrix}
                coslambda& -sinlambda&0\
                sinlambda& phantom{-}coslambda & 0\
                0 & 0 & 0 \
                end{pmatrix}.
                $$



                The total rotation is the product of the matrices. Since we apply matrices to vector from left to right, the order is like this:
                $$
                R = Lambda Theta Phi
                $$



                From programming point of view, you can either derive the final equation for the corners on paper and then write it in code. Or preferably, add multiplication by matrix as a function your code and apply matrix multiplication on demand. The latter case will give you more flexibility and is probably less prone to bugs.






                share|cite|improve this answer









                $endgroup$



                If you are aware of matrices, you can construct your rotation matrix from simple rotation matrices. Let's have rectangle parallel to plane $yz$ (with $z$ being the axis of spherical coordinates), sides parallel to $y$ and $z$ and center on the sphere (you can derive the coordinates of the vertices yourself).



                We first rotate rectangle around its central point (axis $x$) by angle $varphi$:
                $$
                Phi=begin{pmatrix}
                0 & 0 & 0 \
                0 & cosvarphi& -sinvarphi\
                0 & sinvarphi& phantom{-}cosvarphi
                end{pmatrix}.
                $$

                Then we rotate the rectangle by given latitude angle (around axis $y$):
                $$
                Theta=begin{pmatrix}
                phantom{-}costheta& 0& sintheta\
                0 & 0 & 0 \
                -sintheta& 0& cosvarphi
                end{pmatrix}.
                $$

                Finally, we will rotate around axis $z$ by longitude angle $lambda$:
                $$
                Lambda=begin{pmatrix}
                coslambda& -sinlambda&0\
                sinlambda& phantom{-}coslambda & 0\
                0 & 0 & 0 \
                end{pmatrix}.
                $$



                The total rotation is the product of the matrices. Since we apply matrices to vector from left to right, the order is like this:
                $$
                R = Lambda Theta Phi
                $$



                From programming point of view, you can either derive the final equation for the corners on paper and then write it in code. Or preferably, add multiplication by matrix as a function your code and apply matrix multiplication on demand. The latter case will give you more flexibility and is probably less prone to bugs.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 11 '18 at 14:10









                Vasily MitchVasily Mitch

                2,3141311




                2,3141311






























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