Monday, November 21. 2005

Hanke's Response on OGC Support in Google Earth

Last week GIS Monitor offered a review of a French company’s review of Google Earth as a tool for military and defense. The editor followed up with several questions for John Hanke, the company’s Product Director for Local Maps & Earth. This question and answer were very interesting to me.

Does Google Earth abide by OGC standards, as claimed in the French report? In general, what is Google's attitude toward standards?

"We currently support the import of WMS data into our enterprise client. You can subscribe to a WMS server and see that as an overlay on the Google Earth data as you pan around. Google Earth is a good complement to a traditional GIS system — it is not a replacement for one. It is about a geo-browsing experience. We support some OGC standards, particularly WMS. OGC standards were created for GIS companies; they are not consumer-oriented standards. We have contacts with OGC and would like to see the emergence of consumer-oriented standards. However, it is pretty easy to add data to Google Earth using KML and people have written converters [to facilitate that]. The bulk of the world's GIS data lives in proprietary ESRI systems — not in OGC-compliant ones. ESRI has announced its intention to support KML."

First off, full disclosure: I consult to OGC and have for several years.

Some thoughts:

“Import of WMS data” – I could be wrong, but there is no such thing as WMS data. WMS servers pick up a graphic - think JPEG or PNG - and delivers it to a client. It's a snapshot of the result from the GIS. The data underneath could be anything – ESRI shape files, DGN, MapInfo, images, whatever. If anything, WMS data is a simple bitmap sent with further information about where to locate it, etc.

“subscribe to a WMS server” – I suppose for Google subscriptions are big deal. Most people talk about connecting to a WMS server.

“We support some OGC standards.” I wonder which ones besides WMS? For those not keeping count, here’s the current list.

“OGC standards were created for GIS companies; they are not consumer-oriented standards.” I admit ignorance – what’s the difference? Is the Wi-Fi standard for electronics companies or consumers? I think both, but perhaps this is more subtle.

“The bulk of the world's GIS data lives in proprietary ESRI systems — not in OGC-compliant ones.” It’s interesting to note that several of ESRI’s products implement OGC specs and others have passed conformance testing for them. So, I wonder if that statement will be outdated soon?

Oh, and that Enterprise Client Hanke mentions, don’t look for any details about its support for WMS on the Google Earth page. The only details I found were on a Keyhole page.

The client, so far as I can tell only comes with the Enterprise version of Google Earth. And, exactly how do you access WMS servers? “A 2D overview map window is available. This overview map can be driven by a WMS-compliant server.”