Sonar based maps were edge matched to the IKONOS based maps and GIS topologic quality was established by executing ArcView extension routines that check for: overlapping polygons, multipart polygons, sliver polygons and void polygons. Additionally checks for adjacent polygons with the same habitat attributes were completed. All errors were identified and corrected. This file is believed to be logically consistent.
A first draft map was completed and features in the imagery where uncertainties existed, due to confusing or difficult to interpret signatures, were identified for ground validation. An ArcGIS point theme was generated with points positioned on the features of uncertain habitat type or along transects though gradients between habitat types. The GIS points were converted to GPS waypoints and were navigated to in the field using a Trimble GeoExplorer 3 GPS data logger.
A benthic habitat characterization was conducted at each site by drop camera, free diving, or where water depth and clarity permitted, by observation from the surface. GPS data were collected at each location and site ID, depth, habitat type, zone and the method used to make the assessment were recorded. A second draft of the map was generated incorporating these ground validation data.
The sonar and satellite based maps were edge matched primarily by clipping out any areas of overlap and retaining the sonar derived map. Polygon edges were merged where attributes matched and seams corrected for any inconsistencies.