Bug: a88/30cd

ID :	30cd0e64-9712-422f-a7f8-f0af3464bd76
Short name :	a88/30cd
Status :	closed
Severity :	minor
Assigned :
Reporter :	Pontus Lurcock <pont@talvi.net>
Creator :	Pontus Lurcock <pont@talvi.net>
Created :	Wed, 07 Nov 2012 20:43:24 +0000
Target :	1.03
Summary :	a95s do not project onto upper hemisphere properly [255]

Comment:

--------- Comment ---------
ID: f0579942-bcbc-4c4f-acfc-c7e2330b2754
Short name: a88/30cd/f05
From: Pontus Lurcock <pont@talvi.net>
Date: Wed, 07 Nov 2012 20:43:24 +0000

From JMG.

Comment:

--------- Comment ---------
ID: ad2f9a7e-ea80-41d6-a561-9f80ad5b0534
Short name: a88/30cd/ad2
From: Pontus Lurcock <pont@talvi.net>
Date: Sat, 17 Nov 2012 19:23:20 +0000

I think I've just accidentally reproduced this, or something like
it. Create a site direction with an a95 region that crosses the 
equator -- it just gets cut off straight rather than having the
"other" part correctly projected! "Straight" here meaning a 
straight line on-screen rather than on the sphere.

Comment:

--------- Comment ---------
ID: 11989b24-909a-43ba-9c5e-e6d53f2cfb86
Short name: a88/30cd/119
From: Pontus Lurcock <pont@talvi.net>
Date: Wed, 06 Feb 2013 16:06:56 +0000

Despite my earlier comment, I can't reproduce this now. I'm 
beginning to suspect that it's actually an artefact of the way 
equator-crossing small circles project on an EA plot: if (say)
the centre of the circle is a little below the equator, the 
upper half will plot as a relatively straight line, which looks
odd but does actually conform to the projection. Next steps on
this one: contact JMG for an example file. If he supplied one,
check PuffinPlot's plot vs. any other implementations I can
find of EA plots -- PmagPy might be a good start.

Comment:

--------- Comment ---------
ID: abb5ae18-d931-4622-8864-2f6ee8914222
Short name: a88/30cd/abb
From: Pontus Lurcock <pont@talvi.net>
Date: Wed, 06 Feb 2013 16:08:36 +0000

See also example file in bugs/255_-_a95s_do_not_project

Comment:

--------- Comment ---------
ID: 252735f8-5618-42cc-9c25-ad50788543f8
Short name: a88/30cd/252
From: Pontus Lurcock <pont@talvi.net>
Date: Sun, 12 Oct 2014 18:47:36 +0000

I've compared the counterintuitively strange-looking projection with
PmagPy's equarea_ell.py and with Stereonet v9. equarea_ell is a bit
buggy and actually plots two (very similar) projected lines; PuffinPlot
matches one of them exactly. PuffinPlot also matches Stereonet's
projection. Absent a test case from JMG, I'm closing this as can't
reproduce.

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