From 31774047deb0266c070cb0e70f63ae01364df8d4 Mon Sep 17 00:00:00 2001
From: Rob Norris <rw_norris@hotmail.com>
Date: Sun, 16 Nov 2014 11:05:13 +0000
Subject: [PATCH] [DOC] Update GeoRef Layer documentation for the latest
 capabilities.

---
 help/C/georef_layer.xml | 37 +++++++++++++++++++++++++++++++++++++
 help/C/viking.xml       |  6 +++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/help/C/georef_layer.xml b/help/C/georef_layer.xml
index fda36061..e8b5e9e9 100644
--- a/help/C/georef_layer.xml
+++ b/help/C/georef_layer.xml
@@ -8,6 +8,43 @@
 <para>
 This layer allows one to use any image as a map. You will need to tell it how to align the map to a position in the world and the scale of map.
 </para>
+<para>
+When a new image is selected the values from a <ulink url="http://en.wikipedia.org/wiki/World_file">World File</ulink> will automatically be tried to be found. 
+(subject to the setting in <xref linkend="prefs_external"/>)
+</para>
+<note>
+<para>
+&appname; does not currently support skew values and since World Files do not contain what coordinate system the coordinate values are in - &appname; assumes they are in UTM.
+</para>
+</note>
+<para>
+If you do not know the scale of the map but know the coordinates of both upper left and lower right coordinates,
+ you can enter these coordinates (Lat/Lon only) and then use the <guibutton>Calculate MPP values from coordinates</guibutton> button.
+</para>
+<para>
+The map once loaded can be repositioned via <xref linkend="georef_tools"/>, which may be easier than trying to edit the raw property values.
+</para>
+
+<section><title>Map Layer Properties</title>
+<para>
+Configurable properties:
+</para>
+<itemizedlist>
+<listitem>
+	<para>The map image file.</para>
+</listitem>
+<listitem>
+	<para>X + Y Scales in metres per pixel.</para>
+</listitem>
+<listitem>
+	<para>Coordinates of the upper left corner of the map (either UTM or Lat/Lon value).</para>
+</listitem>
+<listitem>
+	<para>Alpha. Control the Alpha value for transparency effects using a value between 0 and 255 with the default being 255 for a fully solid image, whereas 0 is transparent.</para>
+</listitem>
+</itemizedlist>
+</section><!-- Prop END -->
+
 <section><title>Layer Operations</title>
 <section><title>Zoom to Fit Map</title>
 <para>
diff --git a/help/C/viking.xml b/help/C/viking.xml
index f5f6dabd..58bc72cf 100644
--- a/help/C/viking.xml
+++ b/help/C/viking.xml
@@ -2075,7 +2075,7 @@ For Linux you can override this with the setting in the <xref linkend="prefs_ext
 
 </section>
 
-<section><title>Georef Map Layer Tools</title>
+<section id="georef_tools"><title>Georef Map Layer Tools</title>
 <para>
 You must have a <xref linkend="GeoRef"/> Map Layer selected to use these tools.
 </para>
@@ -2275,6 +2275,10 @@ Generally if you have a system with lots of memory it's recommended to increase
 <para>This allows setting the specific location of GPSBabel.</para>
 <para>&appname; will need to be restarted for this setting to take effect.</para>
 </section>
+<section><title>Auto Read World Files</title>
+<para>If this is on, when a new image is selected for the GeoRef layer then the associated world file will be read to find the scale and positional properties.</para>
+<para>The associated file is based on filename patterns; e.g. if the image is <filename>filename.jpg</filename> - then the world file may be <filename>filename.jpgw</filename> or <filename>filename.jgw</filename></para>
+</section>
 </section>
 
 <section id="prefs_osm" xreflabel="OpenStreetMap Traces Preferences"><title>OpenStreetMap Traces</title>
-- 
2.39.5