geotrellis核密度分析(spark分布式计算)

代码：

  def ncdensityrdd(): Unit ={

    val conf = new SparkConf().setMaster("local").setAppName("Kernel Density")
    val sc = new SparkContext(conf)
    val tl = TileLayout(7, 4, 100, 100)
    val ld = LayoutDefinition(extent, tl)

    val kernelWidth=9
    def ptfToExtent[D](p: PointFeature[D]) = pointFeatureToExtent(kernelWidth, ld, p)
    def pointFeatureToExtent[D](kwidth: Double, ld: LayoutDefinition, ptf: PointFeature[D]): Extent = {
      val p = ptf.geom

      Extent(p.x - kwidth * ld.cellwidth / 2,
        p.y - kwidth * ld.cellheight / 2,
        p.x + kwidth * ld.cellwidth / 2,
        p.y + kwidth * ld.cellheight / 2)
    }

    def ptfToSpatialKey[D](ptf: PointFeature[D]): Seq[(SpatialKey,Poi