Alternative Formats

In addition to image and movie files, Science On a Sphere® has limited support for KML and WMS data sources.

SOS supports Keyhole Markup Language (KML) 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 necessary.

More information on these commands can be found in the Playlist Reference Guide.

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 faster.

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 sos.support@noaa.gov 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.

https://www.gebco.net/data_and_products/gebco_web_services/web_map_service/mapserv?request=getmap&service=wms&BBOX=-90,-180,90,360&crs=EPSG:4326&format=image/jpeg&layers=gebco_latest&width=1200&height=600&version=1.3.0

To use a WMS URL with SOS, you set it as the value for the layerdata attribute.

#WMS Data Example
layerdata = //WMS//https://www.gebco.net/data_and_products/gebco_web_services/web_map_service/mapserv?Service=WMS&WMS=worldmap&Version=1.1.0&Request=GetMap&BBox=,,,&SRS=EPSG:4326&Width=&Height=&Layers=gebco_latest&Format=image/png

Four things have changed: //WMS//, Height=<PIXELHEIGHT>, Width=<PIXELWIDTH>, BBox=<WEST>,<SOUTH>,<EAST>,<NORTH>. 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.

Also to note is that the CRS= value should either be equal to CRS:84 or EPSG:4326. If CRS= is not working, try SRS= as in the example above.

See the Web Map Service (WMS) Tutorial for more information on using WMS in SOS.

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. If you try out your WMS dataset and you get a loading error, you’ll need to go into the /tmp directory and delete the directory corresponding to the URL you put in your layerdata field and then make modifications to your layerdata value and then try again.

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.