Company Blog


Google Earth Enterprise Server: Exporting a Structured Layers List

In the Virtual Alabama program for the State of Alabama, the majority of users employ the Google Earth Enterprise Desktop Client to connect to and use the Virtual Alabama system. But a number of users required access directly via web browser, either because the desktop client was not locally installed or to enable access to Virtual Alabama at remote locations.

So we wrote a javascript web viewer for Virtual Alabama, using the Google Earth Plug-in, rendering the entire Virtual Alabama data library in a web browser, with no desktop client installation required.

The challenge, then, became how to maintain a duplicate copy of the layers database for display in our javascript viewer, for searching, and for integration with layers from other sources. While the geographic data is stored on the enterprise servers and rendered by the plug-in, we needed a copy of the layer tree's structure to import into our databases to create a tree menu in the javascript viewer similar to what is displayed in Google Earth, allowing users to find layers and turn layers on and off. A further complication is that this duplicate layers structure had to be updated frequently, whenever new data was published or reorganized within the Virtual Alabama system.

The key was in files named dbroot.v5.postamble.DEFAULT on the enterprise servers, newly created with each database publish. 

This is an example of one row from one of those files:

<etNestedLayer> [More Imagery]
		118 	"0b14797e-a3b3-11e2-9e11-b8ff64cb455c" 	"More Imagery" 	"" 	true 	true 	true 	false 	true 	"All Layers" 	24 	"icons/More_Imagery.png" 	"" 	"" 	"" 	"" 	true 	"" 	"" 	"" 	"" 	"" 	"" 	-1 	-1 

Contained within is a list of all published layers, including the layer name, in this example, More Imagery, the Google Earth ID, just before the name, which is used to enable the layer via javascript and the plug-in, the parent layer name, to determine where the layer belongs in the tree's hierarchy, in this example, just below All Layers, and the path to the layer's icon. This provided all the information we need for our system to build a complete layer tree.

Next, we created a service to automatically retrieve this file as need, process the data to create a list of layers, organize them hierarchically, associate appropriate icons, enable layer searching and integration, and update our web-based javascript Google Earth client to reflect new or updated layers.

Now, with the press of a button, our Desktop and Web clients are automatically in sync with the current state of the Virtual Alabama Google Earth Enterprise Servers.

Safe Schools: Indoor Google StreetView

With the Virtual Alabama School Safety Systems (VAS3), there are multiple projects going simultaneously.  One of these projects is the "Indoor Google StreetView" project.  This project includes the creation of "walk throughs" of rooms and hallways through the building.

The process begins with the collection of photos using a very specific device.  This camera system allows for the remote triggering via wifi and download of captured photographs to a user's cell phone or tablet.  The transferred files are automatically stitched together to produce a high quality panoramic image.  Here is a sample of the raw output from our camera system.

Source Image Post Stitching

The next step include the mapping of the positions of where each set of images were captured.  This is done using a mapping interface designed and developed by my team we call the Floor Plan Annotation Tool (FPAT).

Floor Plan Annotation Tool (FPAT)

In the FPAT we are able to actually generate the tiles needed for ingestion into Google StreetView using the "360 View Manager" module by selecting the panoramic image and queue it for tiling.  The tiled Google StreetView dataset is then associated to each point on the map, therefore completing the process.

The following is an example of a final product from the process.