SOS supports Keyhole Markup
data in addition to the previously existing movie and image formats. KML is a
popular specification and actively used with Google Earth for displaying data
on a sphere. The initial SOS KML capability supports a limited set of the
entire specification, which includes many of the commonly used KML features you
would typically display in Google Earth.
Typically, KML files are used with Google Earth which allows users to display
information on a virtual sphere similar to SOS. There are a couple of
differences to be aware of. Google Earth has additional space around the sphere
where legends, icons, or other meta information can be displayed. SOS has only
the sphere for displaying data. By default, all ancillary information is
displayed at point 0° North, 180° East. Each subsequent piece is staggered from
this starting point. This is user configurable. Within the playlist, use
kmllegendxoffset and kmllegendyoffset to specify a new location.
KML Placemarks or Icons referenced in KML may appear small on the sphere.
Additional playlist parameters have been included to scale icon’s to make them
more visible on the sphere. Use kmlplacemarkscale to scale these features if
Often, KML files reference remote data via a web address. KML files of this
nature require SOS to have access to the internet to retrieve these files.
Depending upon your network connectivity and the number of external links
referenced in the KML file, the initial load may take some time. SOS will
perform local caching of downloaded files and subsequent loads will perform
It is strongly recommended to test KML files prior to any presentation to
insure data is cached locally and the presentation is not delayed by waiting
for remote files to be retrieved. When an SOS playlist references a KML
dataset, SOS will parse the file and store any temporary or cache information
in the system temporary directory. The default is /tmp on SOS systems.
The SOS software does not support the entire KML specification. Here is a list
of major items not currently supported in this release: Tours, Fly To, Features
with 3 Dimensions, Resource Map, Model’s, Regions. If KML data or KML data
isn’t displaying correctly, please contact the SOS support team at
email@example.com and include
the problem KML file in your message.
You cannot have multiple KML layers defined within a single playlist item
because we do not support time matching capabilities between various KML files.
Future versions should allow multiple static KML files.
SOS supports loading imagery directly from the Open GeoSpatial Consortium (OGC)
Web Mapping Service (WMS). This
feature requires an internet connection and will not work unless the SOS system
has access to the internet and the referenced WMS Server.
A WMS provides a service allowing users to request data through URLs using
specific key value pairs defining terms such as the width, height, image type,
etc.… A unique feature of the WMS standard allows users to
request subsets of imagery by defining a bounding box using a lower left and
upper right latitude and longitude coordinates. The combination of these
features allows users to host very large high resolution imagery and users can
request smaller versions or subsets of the original imagery. SOS takes
advantage of this functionality through the magnifying glass, allowing users to
see more detail as you increase the zoom level on the sphere.
To use a WMS URL with SOS, you set it as the value for the layerdata attribute.
#WMS Data Example
Four things have changed: //WMS//, HEIGHT=<image_height>,
WIDTH=<image_width>, BBOX=<bounding_box>. All 4 items are required in order
for WMS data to work correctly with SOS. The first item indicates the following
path to data is a dynamic WMS URL. The last 3 are placeholders for dynamic
fields that change while in use for SOS. For each WMS URL used within SOS,
these values must be replaced exactly as above. SOS will automatically replace
these values when loading the data.
All WMS URL’s are remote data and require SOS to have access to the internet to
retrieve the corresponding imagery. Depending upon your network connectivity
and the performance of the remote WMS server, the initial load may take some
time. SOS will perform local caching of downloaded files and subsequent loading
will perform faster.
It is strongly recommended to test WMS Playlists prior to any presentation
to insure data is cached locally and the presentation is not delayed by waiting
for remote files to be retrieved.
When SOS playlist references a WMS dataset, SOS will retrieve and store any
temporary zoom files or cache information in the system temporary directory.
The default is /tmp on SOS Systems.
With the SOS magnifying glass enabled, SOS will determine a bounding box for
the area currently under view and dynamically retrieve and load that image. A
bounding box cannot be determined around either the North or South Pole. The
nearest image that does not cross the pole will be used.