output_pth = os.path.join(parameters[self.PAR_OUTPUT_FOLDER].valueAsText, '')
        raster = Rt.ReadAsciiRaster(dem_pth)
        filterOut = Filter(raster, "HIGH", "DATA")
        filtered_pth = os.path.join(output_pth, "filtered.asc")
        arcpy.env.overwriteOutput = True
        Rt.WriteRaster(filtered_pth, filterOut )
        arcpy.env.overwriteOutput = False