BTM updateParameters example

gistfile1.py

    def updateParameters(self, parameters):
        validator = getattr(self, 'ToolValidator', None)

        # parameter names
        cols = ['bathy', 'inner', 'outer', 'scale_factor', 'output']
        outer_radius = parameters[cols.index('outer')].valueAsText
        bathy = parameters[cols.index('bathy')].valueAsText
        if outer_radius is not None and bathy is not None:
            raster_desc = arcpy.Describe(bathy)
            # get the cellsize of the input raster; assume same in X & Y
            cellsize = raster_desc.meanCellHeight
            # calculate our 'scale factor':
            scale_factor = math.ceil(float(cellsize) * int(outer_radius) - 0.5)
            # try modifying our scale factor
            parameters[cols.index('scale_factor')].value = scale_factor

        if validator:
             return validator(parameters).updateParameters()