geotrellis.spark.tiling.LayoutDefinition.scala Maven / Gradle / Ivy

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GeoTrellis is an open source geographic data processing engine for high performance applications.

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package geotrellis.spark.tiling

import geotrellis.raster._
import geotrellis.vector.Extent

/**
 * Defines tiled raster layout
 * @param extent      extent covered by the layout tiles, could be greater than extent of data in the layer
 * @param tileLayout  tile layout (tile cols, tile rows, tile pixel size)
 */
case class LayoutDefinition(extent: Extent, tileLayout: TileLayout) extends Product with GridDefinition {
  val CellSize(cellwidth, cellheight) = tileLayout.cellSize(extent)

  lazy val mapTransform = MapKeyTransform(extent, tileLayout.layoutDimensions)

  def tileCols = tileLayout.tileCols
  def tileRows = tileLayout.tileRows
  def layoutCols = tileLayout.layoutCols
  def layoutRows = tileLayout.layoutRows
}

object LayoutDefinition {
  /**
   * Divides given RasterExtent into a TileLayout given a required tileSize.
   * Since padding may be required on the lower/right tiles to preserve the original resolution of the
   * raster a new Extent is returned, covering the padding.
   */
  def apply(grid: GridDefinition, tileSize: Int): LayoutDefinition =
    apply(grid, tileSize, tileSize)

  /**
   * Divides given grid into a TileLayout given tile dimensions.
   * Since padding may be required on the lower/right tiles to preserve the original resolution of the
   * raster a new Extent is returned, covering the padding.
   */
  def apply(grid: GridDefinition, tileCols: Int, tileRows: Int): LayoutDefinition = {
    val extent = grid.extent
    val cellSize = grid.cellSize
    val totalPixelWidth = extent.width / cellSize.width
    val totalPixelHeight = extent.height / cellSize.height
    val tileLayoutCols = (totalPixelWidth / tileCols).ceil.toInt
    val tileLayoutRows = (totalPixelHeight / tileRows).ceil.toInt

    val layout = TileLayout(tileLayoutCols, tileLayoutRows, tileCols, tileRows)
    // we may have added padding on the lower/right border, need to compensate for that in new extent
    val layoutExtent = Extent(
      extent.xmin,
      extent.ymax - (layout.totalRows * cellSize.height),
      extent.xmin + layout.totalCols * cellSize.width,
      extent.ymax
    )

    LayoutDefinition(layoutExtent, layout)
  }
}