GEarth Tour Kml - Weird Slingshot View Effect - kml

Question

I'm running into a weird error with google earth KML tours. I have four different points i'm viewing with the camera look at feature. It works great moving from point to point up until the last point, then it "slingshots" backwards and flys to the final point. Any idea what is causing this or how to fix? In the google earth documentation they list a known issue as " and elements will break the curve created by a series of smooth FlyTos. FlyTo points on either side of these elements will be joined with a linear path.", but there is nothing linear about the slingshot error. Code is below, thank you.
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<Document>
<open>1</open>
<name>NewJersey to Chicago</name>
<gx:Tour>
<gx:Playlist>
<gx:FlyTo>
<gx:duration>5</gx:duration>
<gx:flyToMode>smooth</gx:flyToMode>
<Camera>
<longitude>-74.2340316009802</longitude>
<latitude>40.7126781884856</latitude>
<altitude>2490</altitude>
<heading>281.359605343224</heading>
<tilt>100</tilt>
<roll>0</roll>
<altitudeMode>absolute</altitudeMode>
</Camera>
</gx:FlyTo>
<gx:FlyTo>
<gx:duration>5</gx:duration>
<gx:flyToMode>smooth</gx:flyToMode>
<Camera>
<longitude>-74.314056000094</longitude>
<latitude>40.7243870914955</latitude>
<altitude>5150</altitude>
<heading>281.175459406497</heading>
<tilt>85</tilt>
<roll>0</roll>
<altitudeMode>absolute</altitudeMode>
</Camera>
</gx:FlyTo>
<gx:FlyTo>
<gx:duration>10</gx:duration>
<gx:flyToMode>smooth</gx:flyToMode>
<Camera>
<longitude>-74.6341362250194</longitude>
<latitude>40.771834073193</latitude>
<altitude>10150</altitude>
<heading>281.175459406497</heading>
<tilt>85</tilt>
<roll>0</roll>
<altitudeMode>absolute</altitudeMode>
</Camera>
</gx:FlyTo>
<gx:FlyTo>
<gx:duration>4</gx:duration>
<gx:flyToMode>smooth</gx:flyToMode>
<Camera>
<longitude>-79.1438605513884</longitude>
<latitude>41.3601193917472</latitude>
<altitude>10150</altitude>
<heading>281.175459406497</heading>
<tilt>85</tilt>
<roll>0</roll>
<altitudeMode>absolute</altitudeMode>
</Camera>
</gx:FlyTo>
</gx:Playlist>
</gx:Tour>
</Document>
</kml>

Answer 1

KML tours and the way Google Earth implements them are weird and mysterious indeed.
If you have a really fast segment (long distance in a short duration) that follows a slow segment in your KML tour, Google Earth implements the transition as if you're running backwards to get a running start for the faster segment (to build up momentum for the "jump", if you will).
This doesn't happen if your tour is roughly a constant speed. In your example, if you change your durations from <5,5,10,4> to <5,10,10,300> you will not get the running start effect.