Sunday, 20 May 2012

Cloud Futures #3: Bridging the Gap

Bridging the gap between desktop and on-line GIS follows the first and second instalment, online vector GIS and spatial data validation. GisCloud introduced a free Esri extension to load features and attributes to its file system. This follows other services such as Arc2Earth and  Arc2Googleexcept in the vector domain. Having both Esri @ home and a private cloud I put this new extension through its paces.

East Anglia Fenlands mashup on looks like this on But how do I get there? First you download and install the extension, and it's added to ArcMap for you. Pressing the single button in ArcMap pops up this screen:

click on image to enlarge

Log in via your social media or own login, select the layers to export et voilà! layers get uploaded: 9 layers at 1900 features each totalling 58Mb took 9 min. on a 1mbps up / 20mbps down ADSL line on a stock HP Pavilion g6 notebook running ArcGIS 10 for Home Use (read: ArcView with all extensions).

As with online validation, the usual lessons learned are almost as interesting as the process itself... It's so easy, we have to get something more out if it, don't we? Here are mine:
  • UK Ordnance survey data come in British National Grid (ORD SURV GB) with a defined datum but not ellipsoid, which posts as Transverse Mercator with unnamed ellipsoid and datum, and thus fails the GIScloud import but posts as unprojected
  • a simple reprojection to WGS84 in the file geodatabase fixed that and posts like so:

You can follow Socium's on-line validation output (triangles where adjacent polygons differ by more than one unit). The best part of it, however, is that it took longer to write this blogpost than it took to upload, fix and re-upload the data! How's that for ease-of-use from Esri and