Isofill does not work with mercator if given lat coordinates values -90, 90 (the edges)

[aashish24]

I suggest we try every template that is exposed.

[doutriaux1]

2 issues here.
*) Mercator does not seem to work with points at the poles, stopping at 80S/N works.
*) Wrap around issues -180/180 input seems to be required, 0/360 plots are not good looking. Seems like a VTK projection restrictions, will see if we can actually reload all plots between -180,180

[doutriaux1]

not that it shou;ld make us feel better, but in 1.5.1 (preVTK) it didn't work either see attached

[durack1]

You win points for abstract art however..

[doutriaux1]

ok here's the deal
see: http://en.wikipedia.org/wiki/Mercator_projection
now it clearly states:

the Mercator projection distorts the size and shape of large objects, as the scale increases from the Equator to the poles, where it becomes infinite

So clearly since clt goes all the way to the North, VTK rightfully fails rendering.
VCS projections have always had the "if you don't know what you're doing don't use it"

a few possibilities here:
1- We can remove mercator as one of the default projections (like we did for lambert which suffers the same issue
2- @aashish24 it seems like VTK (rightfully again) gives up on projecting because the lats (plotting a subset -82/82 works) do ou know if there's a way to catch some error VTK probably returned and send this back to the user.
3- even in -82/82 I see some wrapping around issues with continents coastlines. @aashish24 I'm not sure how to address that. Is there a way in VTK projections to tell it "do not cross dateline?" It's always tricky because it might be a legimate line actually going from 355 lon all the way to 5 lon, rather than (usually) a line going from 355 to 365. Usually in grids they deal with this with the clockwise/counterclockwise direction of the points. But I'm not sure it would work here in our continents points files. @williams13 any suggestions?

[aashish24]

which mercator you are using for this one? Mercator are few.. I cna provide detailed information once I know which one template is using.

[williams13]

I see the artful mercator image that Paul commented on, but I don't see the new/correct image. Can you include the image so that we can comment on?

Thanks, Dean

From: Aashish Chaudhary <notifications@github.commailto:notifications@github.com>
Reply-To: UV-CDAT/uvcdat <reply@reply.github.commailto:reply@reply.github.com>
Date: Wednesday, September 3, 2014 9:01 PM
To: UV-CDAT/uvcdat <uvcdat@noreply.github.commailto:uvcdat@noreply.github.com>
Cc: Dean Williams <williams13@llnl.govmailto:williams13@llnl.gov>
Subject: Re: [uvcdat] Isofill does not work with mercator (#587)

which mercator you are using for this one? Mercator are few.. I cna provide detailed information once I know which one template is using.

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Reply to this email directly or view it on GitHubhttps://github.com//issues/587#issuecomment-54403132.

[doutriaux1]

There's no new "Correct" image since this data cannot be plotted "correctly" as is, you need to plot from -82/82 see attached

[doutriaux1]

on the image above you can see the "wrapping" issue with continents