EQC projection doc #412
EQC projection doc #412
Conversation
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Yes I think it makes sense to update the formulas to take into account phi_0. (note: A bit out of scope of this PR, but would probably be good to have some generic intro page for all projections to present the naming conventions of all those common variables. I had no idea what k and h meant until I found paragraph "3.8.1 Scale factors") |
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| .. math:: | ||
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| x = \lambda cos \phi_{ts} |
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I believe \cos should be possible here.
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Not specific to @julien2512's contribution (it is greatly appreciated!), but this highlights the tricky part about this endeavor -- it is really easy to miss math symbols when porting things over.
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@kbevers's plotting script is now merged into |
Yeah, I have a few ideas on how to do that. I will get to it soon(ish). Among other things I want to be able to define an area of interest. For most projections it is fine to just plot the whole world, but in some cases projections are only valid for a certain area. Eventually we will probably also want to have more than one image in the docs for a particular projection. I'll make some sort json-setup file where you can set the proj-string, area, filename, etc. The plotting script can then parse that and make better figures for the doc-pages. |
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I don't know. There might be some magic in sphinx that can do that. For now I would rather keep it simple and just have it in one file. Don't want to over-engineer this from the start :) |
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Yes you are right, it is better to make it works ! |
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Dear all, I tryed myself on tmerc projection (see the pull request). It's harder than eqc and I ve got many asks :
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@hobu You seems to have make tmerc already ! |
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Please let developers close pull requests so we know if stuff has been merged or not.
That's curious and should be investigated further. |
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I noticed that as well when I wrote the Mercator documentation. The libproj text is wrong. Snyder's book is in agreement with the implementation in proj4. I am sure you can find other sources as well. The docs on proj4.org uses formula from Snyder. |
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http://mathworld.wolfram.com/MercatorProjection.html uses the same formula as Snyder (more or less...). Just for fun, I also derived the formula on paper and I get the same result. I am now 100% certain that the spherical inverse mercator function is correct. And the docs reflect what's in the code. |
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Thank you. On an other side, I understand the new doc will respect the proj4 Le 13 sept. 2016 4:57 PM, "Kristian Evers" notifications@github.com a http://mathworld.wolfram.com/MercatorProjection.html uses the same formula — |
Just create a new branch, make your changes and put up another PR on the new branch. |
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@kbevers Thank you, i will do it the day after tomorrow (edit ;) ). |
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@hobu I do not close it on purpose this time /) It was automatic after the branch deletion on my repo. The new pull request is done :) ! |
Here is my second test, I think it will be accepted.
The references I used for are :
https://github.com/OSGeo/proj.4/blob/master/docs/old/libproj.pdf
ftp://ftp.ams.org/pub/tex/doc/amsmath/amsldoc.pdf
make html ;)
Tell me if it's ok, then I will make more.
I have a first question : in proj4 source code, there an optionnal \phi_0 that do not appear in the old documentation formula, but only in the parameters.
May I fix it in the new docs ?
It leads me to a second question about the png generated in that page.
There is "+eqc", but it does not show the parameters [+lat 0= | +lat ts=] as in the old documentation.
How can I improve it ?