Fix enable selecting trackpoints/routepoints via Edit Trackpoint tool when the other...

[andy/viking.git] / help / C / georef_layer.xml

diff --git a/help/C/georef_layer.xml b/help/C/georef_layer.xml
index fda36061a5836c439927566400d4d1466bbaefe3..5ca4135298d989ec8542947a86d559e9e69740d4 100644 (file)
--- 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>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>