[R-sig-Geo] ground overlays in KML

[Barry Rowlingson]

On Wed, Mar 6, 2013 at 2:07 AM, Hodgess, Erin <HodgessE at uhd.edu> wrote:
> Hello again.
>
> I'm not sure if I should ask this here, but I thought it might be a place to
> start:
>
> I'm producing PNG files for ground overlays in Google Earth.  After some
> help from you this afternoon, my png files are ready.  However, the files do
> not run in sequence in Google Earth.  It shows the last file only.
>
> Here is a little bit of the code:

 This works for me, except..

> <kml xmlns:xsd="http://schemas.opengis.net/kml/2.2.0/ogckml22.xsd"
> xmlns:xmlns="http://www.opengis.net/kml/2.2/" version="1.0">
...
> </Document>
> <kml>

 that last tag should be a closing </kml> - but google earth
complained until I changed it so maybe thats a typo that happened when
you chooped a data file up to put in the email! Take CARE!

 Now, you don't say exactly what you are doing. All we have is "the
files do not run in sequence in Google Earth. It shows the last file
only".

 Well, yes, that's because the last one is on top of the others. You
are trying to do some kind of animation? So what have you done with
the animation controller?

 The animation controller has a start and end marker. Initially the
markers will be at the limits of the start and end of the timepoints
of your data. Hit the 'play' button (aka "click to toggle time slider
animation") and it will animate the start point only. The end doesn't
change. Since your top image has an end point within the time range
for all times, it stays visible. What is happening is that the images
underneath it are being animated, but you don't see that because they
are hidden under the top one at all time points.

So... drag the time END point back so it nudges up to the start point
marker. Now that will put the top layers out of range, and just reveal
the earliest bottom layer. Hit play again....

 That's what I do to get an animation. As time goes forward, I see the
blue area shrinking, in three steps.

Barry