Make an ArcView 3.x gridding Generate raster/grids from the point data collection. Grids are an excellent way of publishing data from the collection and also submitting data for statistics or to numerical models.	1. Open AV3.x with the Spatial Analyst extension. 2. Import (+) the Gulf of Mexico coverage via GSM_WWD shapefiles or via GSM_WWD.TXT through the AV3.x table import tool. 3. Use the query tool to select against the null values (-99 numeric, "-" string) in the target data column. The query syntax will be like: "( [Grainsze] <> -99 )". Real-valued points on the map will be highlighted. 4. Using Analysis>NearestNeighbor ..>Distance, or Surface>InterpolateGrid begin the setup of grid size, resolution and type. 5. To simplify the process it is possible to nominate a grid as template using Analysis>Properties>AnalysisExtent. 6. When the grid is calculated and displayed, visit "http://instaar.colorado.edu/~jenkinsc/dbseabed/legends/_avls/_griddings" to collect a suitable legend, or generate a new one. Choice of interpolation technique can strongly affect the visual and scientific value of a gridding.
Collect data points for statistical analysis in EXCEL This might be used, for instance to characterise the sediment properties and variabilities along a trawl track, or in a NMFS statistical area.	1. Open AV3.x 2. Import (+) the Gulf of Mexico coverage via GSM_WWD shapefiles or via GSM_WWD.TXT through the AV3.x table import tool. 3. Select the geographic subset by drawing a box, or performing Theme>SelectByTheme... . 4. Use the whole data selection, or to restrict to samples having real values of a parameter, use the query tool to select against the null values (-99 numeric, "-" string) in the target data column. Check #SelectFromSet to subset the geographic selection. 5. Save the selection as a shapefile [Theme>ConvertToShapefile...] or  for a text output, open the table [Theme>table... or Tool] and then export the selection [File>Export..>#DelimitedText]. 6. Open the DBF (DBase IV) or Text file in Excel. Caution: dBaseIV DBF tables can use fixed-length and zeroed fields in unexpected ways.
Attach grid values to trawl stations Trawl stations often have no associated in-survey information on substrates. This method allows trawl points or point-traverses to collect that data from a stack of dbSEABED grids.	1. Open ArcGis 9.x. 2. Visit Hawth's Ecological Analysis Tools for ArcGIS "http://www.spatialecology.com/index.php" and download the toolbox. Unzip the file, and run the install EXE. Install Hawth's as an extension in ArcGIS (Tools>Extensions>#CHECKOPTION). 3. Open the toolkit and IntersectPointTool using View>Toolsbars>Hawth'sTools>AnalysisTools>IntersectPointTool. 4. Import the trawl point dataset to ArcGIS. Import any grids or polygons that you wish to attach values from, to the points. 5. Fill in values for the IntersectPointTool dialogue, checking IgnoreAllSpatialReference(Projection)Differences if the projections of points and grids/polygons are not uniform. By checking a polygon or grid, you will append a new column to the point dataset table. 6. Press OK. (Entering a column name will append yet more columns to the data table.) Open the trawl point dataset table (R-CLICK_Theme>OpenAttributeTable) to inspect the results. That table can then be brought into analysis packages starting with EXCEL. There are many other useful ecological GIS tools in Hawth's toolbox.
Author: Chris Jenkins Date: 10 Sep 2007 Location: New Orleans