(r1) STC-1_33-Erratum-2 < IVOA

IVOA Web>IvoaDataModel>STC>STC-1_33-Errata>STC-1_33-Erratum-2 (revision 1) (raw view)~~EditAttach~~

---+ [[STC]]-1.33 Erratum 2: 

Author: DM WG

Date last changed: 2018-11-18

Date accepted:
---++ <a name="Rationale"></a>Rationale 

This erratum is to correct an error reported at the IVOA interop in Victoria, BC: May 2018

   * <a target="_blank" href="http://wiki.ivoa.net/internal/IVOA/InterOpMayy2018DAL/ivoa_201805_micol_polygons.pdf">POLYGON with different orientations issue</a>
---++ <a name="Erratum_Content"></a>Erratum Content 
<div title="Page 6">

Section 4.5.1.4 (pg 30-31: Region.Polygon) states:
<div title="Page 30">

"<span style="background-color: transparent;">The inside of the region is defined as that part of coordinate space that is encircled by the polygon in a counter-clockwise sense. What this means is that, in a plane, if A &gt; 0, the &ldquo;inside&rdquo; of the polygon is included; if A &lt; 0, the &ldquo;outside&rdquo; is selected. On a sphere with a left-handed (celestial) coordinate system, if A &gt; 0, one has identified the inside of the polygon; <strong>if A &lt; 0, one used the &ldquo;outside&rdquo; angles of the polygon and the area </strong></span><span style="background-color: transparent;"><strong>is really 4&pi; &minus; A</strong> . "</span>
</div>

The incorrect text is shown in bold text:
<div title="Page 7">

This is also wrong because if A &lt; 0 then 4*pi &ndash; A is &gt; 4*pi, and that cannot be.

</div>

The correct text is:

<span style="background-color: transparent;">"if A &lt; 0, one used the &ldquo;outside&rdquo; angles of the polygon and the area is really 4&pi; <strong>+</strong> A  "</span>
</div>

---++ <a name="Impact_Assessment"></a>Impact Assessment 
---++ <a name="Notes"></a>Notes 

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Topic revision: r1 - 2018-11-18 - MarkCresitelloDittmar

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