Lines between points can be curved. To achieve this, you must specify <a href="http://docs.amcharts.com/3/javascriptmaps/LinesSettings#arc"><code>arc</code></a> property in your <a href="http://docs.amcharts.com/3/javascriptmaps/LinesSettings"><code>linesSettings</code></a> config. Allowed values are from -1 to 1. You can also specify <a href="http://docs.amcharts.com/3/javascriptmaps/MapLine#arc"><code>arc</code></a> for individual lines in case you need curve to be more or less intense.