Importing float grid files.

These floating point grids are created using the r4toESRI command on linux. The command produces .flt and .hdr files. Both are required for import and need to be in the same directory.

Open ArcToolbox ->Conversion Tools->to Raster ->Float to Raster. Navigate to your input .flt and your output grid.

To run an import batch right-click on the ArcToolbox ->Conversion Tools->to Raster ->Float to Raster and choose Batch. One thing to keep in mind is that Arc doe not permit grid names longer than 13 characters, or starting with anything but a letter.

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Defining projection parameters.

After converting an .flt file to a grid, its projection must be defined. To do that, right click on the grid in ArcCatalog, go to Properties and scroll down to Spatial Reference->Edit. Follow the wizard and define the parameters. For OMG datasets it is usually Mercator with a central meridian of -180.00 degrees and a standard parallel defined in the geometa file of the dataset.

If your want to define a projection for several datasets that share the same parameters, you can do so through the ArcToolbox interface. ArcToolbox->Samples->Data Management->Projections->Batch Define Coordinate System.

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Creating hillshaded grids

Drop down the Spatial Analyst menu ->Surface Analysis-> Hillshade. Make sure the input surface is want you want it to be. Define your parameters (or use default). Define your output raster location (otherwise a temporary grid is created).

Changing grid symbology.

Bathymetry: Right –click->Properties->Symbology->choose color ramp (we’ve been using one called Precipitation)->Stretch (use min-max and edit your low-high values to suit the data). Click the display tab and set the transparency to 65%).