From 64a58b0b51def7a74d5c0a29aa5cc43ab74ca3a2 Mon Sep 17 00:00:00 2001 From: Patrick Dowler Date: Wed, 8 Nov 2023 13:47:14 -0800 Subject: [PATCH] coordinate limits more flexible to allow for other coordinate systems circle, range, and polygon refer to point so this is specified in a single place --- DALI.tex | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/DALI.tex b/DALI.tex index 45444a9..9eebbb0 100644 --- a/DALI.tex +++ b/DALI.tex @@ -747,8 +747,9 @@ \subsection{Point} 12.3 45.6 \end{verbatim} -In spherical coordinates, all longitude values must fall within [0,360] and all -latitude values within [-90,90]. +All coordinate values must fall within the minimal range of values appropriate for the +coordnate system in use. For example, equatorial coordinate limits are [0,360) for longitude +and [-90,90] for latitude; other coordinate systems may define different limits. There is no general purpose definition of minimum and/or maximum point values, but specific services may define something that is applicable in a more limited context. @@ -765,8 +766,7 @@ \subsection{Circle} 12.3 45.6 0.5 \end{verbatim} -In spherical coordinates, all longitude values must fall within [0,360] and all -latitude values within [-90,90]. +Valid coordinate value limits are specified by \verb|xtype="point"| above. Circle-valued service parameters may include additional metadata like minimum and or maximum value. These are specified using a custom interpretation of the @@ -795,11 +795,12 @@ \subsection{Range} includes values from 10 to 11 (coordinate1) and from 20 to 21 (coordinate2). -In spherical coordinates, coordinates are longitude followed by latitude; longitude values must -fall within [0,360] and all latitude values within [-90,90]. This range form is used as part of -the value of the POS parameter in \citep{2015ivoa.spec.1223D} and \citep{2017ivoa.spec.0517B} -(see also "shape" below). A range can span the meridian (longitude 0): 359 1 -1 1 is interpreted -as the small (2x2 degree) coordinate range from 359 across the meridian to 1 degree longitude. +Valid coordinate value limits are specified by \verb|xtype="point"| above. +This range form is used as part of the value of the POS parameter in +\citep{2015ivoa.spec.1223D} and \citep{2017ivoa.spec.0517B} (see also "shape" below). +For example, a range can span the meridian (longitude 0): 359 1 -1 1 is interpreted +as the small (2x2 degree) coordinate range from 359 across the meridian to 1 degree +longitude. Range-valued service parameters may include additional metadata like minimum and or maximum value. These are specified using a custom interpretation of the @@ -828,8 +829,8 @@ \subsection{Polygon} 10.0 10.0 10.2 10.0 10.2 10.2 10.0 10.2 \end{verbatim} -In spherical coordinates, all longitude values must fall within [0,360] and all -latitude values within [-90,90]. Vertices must be ordered such that the polygon +Valid coordinate value limits are specified by \verb|xtype="point"| above. +Vertices must be ordered such that the polygon winding direction is counter-clockwise (when viewed from the origin toward the sky) as described in \citep{2007ivoa.spec.1030R}.