GeoTrellis 0.9 code snippet for merging rasters.

merge.scala

import geotrellis._
import geotrellis.source._
import geotrellis.raster._
import geotrellis.data.arg._

object Main {
  def main(args:Array[String]):Unit = {
    println("Merging...")
    GeoTrellis.init(GeoTrellisConfig("/home/rob/data/sf/catalog.json"))

    try {
      val outpath = "/home/rob/data/sf/dem/sf-dem.arg"
      val outname = "sf-dem"

      val names = (1 to 4).map(i => s"sf-dem$i")

      val extent = Extent(-1.3642671917813445 * math.pow(10,7),
        4537301.94769072,
        -1.3618479632115778 * math.pow(10,7),
        4556831.701332695)
      val info = RasterSource(names.head).info.get
      val rasterType = info.rasterType

      val fullExtent = names.map(RasterSource(_).info.get.rasterExtent.extent).reduce(_.combine(_))
      val fullRe = info.rasterExtent.createAligned(fullExtent)

      val re = info.rasterExtent.createAligned(extent)

      val data = RasterData.emptyByType(rasterType,fullRe.cols,fullRe.rows)

      for(name <- names) {
        println(s"Processing $name")
        val rs = RasterSource(name)
        val r = rs.get
        for(col <- 0 until fullRe.cols;
          row <- 0 until fullRe.rows) {
          val (x,y) = fullRe.gridToMap(col,row)
          val (dcol,drow) = r.rasterExtent.mapToGrid(x,y)
          if(dcol >= 0 && dcol < r.rasterExtent.cols &&
             drow >= 0 && drow < r.rasterExtent.rows) {
            data.setDouble(col,row, r.getDouble(dcol,drow))
          }
        }
      }

      val raster = Raster(data.warp(fullRe,re),re)

      ArgWriter(rasterType).write(outpath,raster,outname)
    } finally {
      GeoTrellis.shutdown
    }
  }
}