5、GeoTrellis-读取栅格文件

读取单波段的栅格

import geotrellis.raster.io.geotiff.SinglebandGeoTiff
import geotrellis.raster.io.geotiff.reader.GeoTiffReader

object demo4 {

  def main(args:Array[String]): Unit = {
    val geoTiff: SinglebandGeoTiff = GeoTiffReader.readSingleband("/Users/mocker/Documents/test/jpeg-test-small.tif");
    println(geoTiff)
  }
}

读取多波段栅格

mport geotrellis.raster.io.geotiff.{MultibandGeoTiff, SinglebandGeoTiff}
import geotrellis.raster.io.geotiff.reader.GeoTiffReader

object demo4 {

  def main(args:Array[String]): Unit = {
    val geoTiff: MultibandGeoTiff = GeoTiffReader.readMultiband("/Users/mocker/Documents/test/jpeg-test-small.tif");
    println(geoTiff)
  }

使用流读取栅格

通过流读取的tif，单个小文件可以完整的读取，大文件则Java虚拟机会内存溢出崩溃，大文件和小文件都有一个共同之处，所选的区域越小读取的速度也快，所以对栅格读取区域的范围要严格的控制，避免程序崩溃。

使用流读取指定区域的栅格数据

import geotrellis.raster.io.geotiff.{MultibandGeoTiff, SinglebandGeoTiff}
import geotrellis.raster.io.geotiff.reader.GeoTiffReader
import geotrellis.vector.Extent

object demo5 {

  def main(args:Array[String]): Unit = {
    val path: String = "/Volumes/Samsung_T5/1.tif";
    //指定区域
    val e: Extent = Extent(361557.21354599966, 3374714.92064873, 361559.67652580043, 3379714.2052475177);

    //单波段读取
    SinglebandGeoTiff(path, e)
    GeoTiffReader.readSingleband(path, e)

    //多波段读取
    MultibandGeoTiff(path, e)
    GeoTiffReader.readMultiband(path, e)

    //单波段读取
    SinglebandGeoTiff(path, Some(e))
    GeoTiffReader.readSingleband(path, Some(e))

    //多波段读取
    MultibandGeoTiff(path, Some(e))
    GeoTiffReader.readMultiband(path, Some(e))
  }

使用流读取已加载的栅格进行裁剪

通过裁剪读取已经加载的tif数据，使用此方法不需要去读取文件，直接就可以访问数据，先加载文件再进行裁剪。

import geotrellis.raster.io.geotiff.reader.GeoTiffReader
import geotrellis.raster.io.geotiff.{MultibandGeoTiff, SinglebandGeoTiff}
import geotrellis.vector.Extent

object demo6 {

  def main(args:Array[String]): Unit = {
    val path: String = "/Volumes/Samsung_T5/1.tif";
    //指定区域
    val e: Extent = Extent(361557.21354599966, 3374714.92064873, 361559.67652580043, 3379714.2052475177);

    //单波段读取裁剪
    SinglebandGeoTiff.streaming(path).crop(e)
    println(SinglebandGeoTiff.streaming(path).crop(e))
    GeoTiffReader.readSingleband(path, true).crop(e)

    //多波段读取裁剪
    MultibandGeoTiff.streaming(path).crop(e)
    GeoTiffReader.readMultiband(path,true).crop(e)
  }
}