What is GeoTrellis?¶

GeoTrellis is a Scala library and framework that uses Apache Spark to work with raster data. It is released under the Apache 2 License.

GeoTrellis reads, writes, and operates on raster data as fast as possible. It implements many Map Algebra operations as well as vector to raster or raster to vector operations.

GeoTrellis also provides tools to render rasters into PNGs or to store metadata about raster files as JSON. It aims to provide raster processing at web speeds (sub-second or less) with RESTful endpoints as well as provide fast batch processing of large raster data sets.

Why GeoTrellis?¶

Raster processing has traditionally been a slow task, which has prompted advances in vector data processing as an alternative. Raster data isn’t going anywhere, however, with more and more satellite data made public every year. GeoTrellis is an answer to the growing need for raster processing at scale. We personally have handled terabyte-level data sets, but really we are only bound by the theoretical limits of Apache Spark. By scale then, we mean arbitrarily large.

Contact and Support¶

You can find more information and talk to developers (let us know what you’re working on!) at:

Hello Raster!¶

Here’s a small example showing a routine focal operation over a single Tile:

scala> import geotrellis.raster._
import geotrellis.raster._

scala> import geotrellis.raster.mapalgebra.focal._
import geotrellis.raster.mapalgebra.focal._

scala> val nd = NODATA
nd: Int = -2147483648

scala> val input = Array[Int](
nd, 7, 1, 1,  3, 5, 9, 8, 2,
9, 1, 1, 2,  2, 2, 4, 3, 5,
3, 8, 1, 3,  3, 3, 1, 2, 2,
2, 4, 7, 1, nd, 1, 8, 4, 3)
input: Array[Int] = Array(-2147483648, 7, 1, 1, 3, 5, 9, 8, 2, 9, 1, 1, 2,
2, 2, 4, 3, 5, 3, 8, 1, 3, 3, 3, 1, 2, 2, 2, 4, 7, 1, -2147483648, 1, 8, 4, 3)

scala> val iat = IntArrayTile(input, 9, 4)  // 9 and 4 here specify columns and rows
iat: geotrellis.raster.IntArrayTile = IntArrayTile([I@278434d0,9,4)

// The asciiDraw method is mostly useful when you're working with small tiles
// which can be taken in at a glance
scala> iat.asciiDraw()
res0: String =
"    ND     7     1     1     3     5     9     8     2
9     1     1     2     2     2     4     3     5
3     8     1     3     3     3     1     2     2
2     4     7     1    ND     1     8     4     3
"

scala> val focalNeighborhood = Square(1)  // a 3x3 square neighborhood
focalNeighborhood: geotrellis.raster.op.focal.Square =
O  O  O
O  O  O
O  O  O

scala> val meanTile = iat.focalMean(focalNeighborhood)
meanTile: geotrellis.raster.Tile = DoubleArrayTile([D@7e31c125,9,4)

scala> meanTile.getDouble(0, 0)  // Should equal (1 + 7 + 9) / 3
res1: Double = 5.666666666666667