Differences

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--- en:documentation:projection_comparison [2013/01/13 14:08] – pch
+++ en:documentation:projection_comparison [2015/11/06 20:43] (current) – external edit 127.0.0.1
@@ Line 2: / Line 2: @@
 ===== Large field of view =====
+The larger field of vision make the more visual difference between the different projection.\\
+The example show a field of 150° and 360° wide using the different options available in the menu [[chart_coordinates|Setup -> Chart, Coordinates]]
 ==== MER, Mercator ====
 ° FOV, standard and oblique :\\
@@ Line 32: / Line 33: @@
 ==== ARC, full sky ====
-{{:en:documentation:arcfull.png?200|}}
+When you click the "Show all sky" button{{:en:documentation:i42.png|}} the projection automatically change to the ARC full sky show below.\\
+This same change of projection occur if you use simultaneously: an oblique projection, an azimuthal coordinate system, a very wide field of vision, and the altitude at the chart center is greater than 45°. \\
+It return to your selected  projection if you zoom in or move the chart center nearer the horizon.
+{{:en:documentation:arcfull.png?300|}}
 ===== Small field of view =====
+On smaller field of vision the difference between the projections is more subtle but important if you want to match a specific image. \\
+The example here show a FOV of 70° to make some difference visible at this scale, look at the grid curvature for more evidence.
 ==== TAN, Gnomonic  ====