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| author | Howard Butler <howard@hobu.co> | 2016-09-08 17:13:05 -0500 |
|---|---|---|
| committer | Howard Butler <howard@hobu.co> | 2016-09-08 17:13:05 -0500 |
| commit | 94142b9061fd1a6ca64e0e7401f2f7d34d1f261e (patch) | |
| tree | 5e39d6e8967e5684f58c4618696b5f110fe6178d /docs | |
| parent | 57a07c119ae08945caa92b29c4b427b57f1f728d (diff) | |
| download | PROJ-94142b9061fd1a6ca64e0e7401f2f7d34d1f261e.tar.gz PROJ-94142b9061fd1a6ca64e0e7401f2f7d34d1f261e.zip | |
start plugging in some equations from Gerald's docs
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/source/glossary.rst | 41 | ||||
| -rw-r--r-- | docs/source/index.rst | 1 | ||||
| -rw-r--r-- | docs/source/projections/eck1.rst | 14 | ||||
| -rw-r--r-- | docs/source/projections/fouc_s.rst | 21 | ||||
| -rw-r--r-- | docs/source/projections/hatano.rst | 27 | ||||
| -rw-r--r-- | docs/source/projections/wag2.rst | 14 | ||||
| -rw-r--r-- | docs/source/projections/wag3.rst | 12 |
7 files changed, 125 insertions, 5 deletions
diff --git a/docs/source/glossary.rst b/docs/source/glossary.rst new file mode 100644 index 00000000..92b75ecd --- /dev/null +++ b/docs/source/glossary.rst @@ -0,0 +1,41 @@ +.. _glossary:: + +================================================================================ +Glossary +================================================================================ + +.. glossary:: + + Pseudocylindrical Projection + + Pseudocylindrical projections have the mathematical characteristics of + + .. math:: + + \begin {array} + + x &= f(\lambda,\phi) + + y &= g(\phi) + + \end {array} + + where the parallels of latitude are straight lines, like cylindrical + projections, but the meridians are curved toward the center as they + depart from the equator. This is an effort to minimize the distortion + of the polar regions inherent in the cylindrical projections. + + Pseudocylindrical projections are almost exclusively used for small + scale global displays and, except for the Sinusoidal projection, only + derived for a spherical Earth. Because of the basic definition none of + the pseudocylindrical projections are conformal but many are equal + area. + + To further reduce distortion, pseudocylindrical are often presented in + interrupted form that are made by joining several regions with + appropriate central meridians and false easting and clipping + boundaries. Interrupted Homolosine constructions are suited for showing + respective global land and oceanic regions, for example. To reduce the + lateral size of the map, some uses remove an irregular, North-South + strip of the mid-Atlantic region so that the western tip of Africa is + plotted north of the eastern tip of South America. diff --git a/docs/source/index.rst b/docs/source/index.rst index 89c60392..7e4d66ec 100644 --- a/docs/source/index.rst +++ b/docs/source/index.rst @@ -40,6 +40,7 @@ Documentation threads parameters projections/index + glossary diff --git a/docs/source/projections/eck1.rst b/docs/source/projections/eck1.rst index 71f09733..54fc2f5c 100644 --- a/docs/source/projections/eck1.rst +++ b/docs/source/projections/eck1.rst @@ -6,5 +6,17 @@ Eckert I .. image:: ./images/eck1.png :scale: 50% - :alt: Eckert I + :alt: Eckert I + + +.. math:: + + \begin{array} + + x &= 2 \sqrt{2/3\pi} \lambda (1- |\phi|/\pi) + + y &= 2 \sqrt{2/3\pi}\phi + + \end {array} + diff --git a/docs/source/projections/fouc_s.rst b/docs/source/projections/fouc_s.rst index 5a60d0e7..1c5dffa1 100644 --- a/docs/source/projections/fouc_s.rst +++ b/docs/source/projections/fouc_s.rst @@ -6,5 +6,24 @@ Foucaut Sinusoidal .. image:: ./images/fouc_s.png :scale: 50% - :alt: Foucaut Sinusoidal + :alt: Foucaut Sinusoidal + +The `y`-axis is based upon a weighted mean of the cylindrical equal-area and +the sinusoidal projections. Parameter :math:`n=n` is the weighting factor where +:math:`0 <= n <= 1`. + +.. math:: + + \begin{array} + + x &= \lambda \cos \phi / (n + (1 - n) \ cos \phi) + + y &= n \phi + (1 - n) \sin \phi + + \end {array} + +For the inverse, the Newton-Raphson method can be used to determine +:math:`\phi` from the equation for :math:`y` above. As :math:`n -> 0` and +:math:`\phi -> \pi/2`, convergence is slow but for :math:`n = 0`, :math:`\phi = +\sin^1y` diff --git a/docs/source/projections/hatano.rst b/docs/source/projections/hatano.rst index 6660a689..eaf7f18b 100644 --- a/docs/source/projections/hatano.rst +++ b/docs/source/projections/hatano.rst @@ -6,5 +6,30 @@ Hatano Asymmetrical Equal Area .. image:: ./images/hatano.png :scale: 50% - :alt: Hatano Asymmetrical Equal Area + :alt: Hatano Asymmetrical Equal Area + + +:term:`Pseudocylindrical Projection` + +.. note:: + + If the ``+syn`` option is selected, the symmetric form of this projection is + used. Otherwise the asymmetric form is used by default. + +.. math:: + + \begin{array} + + x &= 0.85\lambda cos \theta + + y &= C_y sin \theta + + P(\theta) &= 2\theta + sin 2\theta - C_p sin \phi + + P'(\theta) &= 2(1 + cos 2\theta) + + \theta_0 &= 2\phi + + \end{array} + diff --git a/docs/source/projections/wag2.rst b/docs/source/projections/wag2.rst index 95063695..f9e71354 100644 --- a/docs/source/projections/wag2.rst +++ b/docs/source/projections/wag2.rst @@ -6,5 +6,17 @@ Wagner II .. image:: ./images/wag2.png :scale: 50% - :alt: Wagner II + :alt: Wagner II + +.. math:: + + \begin{array} + + x &= 0.92483 \lambda \cos \theta + + y &= 1.38725\theta + + \sin \theta &= 0.88022 \sin(0.8855\phi) + + \end {array} diff --git a/docs/source/projections/wag3.rst b/docs/source/projections/wag3.rst index beae5662..5b043ef4 100644 --- a/docs/source/projections/wag3.rst +++ b/docs/source/projections/wag3.rst @@ -6,5 +6,15 @@ Wagner III .. image:: ./images/wag3.png :scale: 50% - :alt: Wagner III + :alt: Wagner III + +.. math:: + + \begin{array} + + x &= [\cos\phi_{ts} / \cos ( 2\phi_{ts} / 3)] \lambda \cos (2\phi /3) + + y = \phi + + \end {array} |
