GeoTrellis Chattanooga model demo

This is a demo of GeoTrellis functionality. The demo consists of two parts: the tile ingest process and demo server to query ingested data.

Dependencies

• Java 8
• (optional - for make ingest) Apache Spark
• (optional - for make ingest-docker) Docker

Usage

See the Makefile for full details.

Command	Action
make build	Build ingest/server code
make ingest	Ingest data for use by server
make ingest-docker	Ingest via docker
make server	Start a test server at localhost:8777
make image	Generate a Docker image for deployment

Details

The demo covers Chattanooga with different Byte tiles. (In fact each tile is essentially of type Bit because they only contain the values {0, 1}). Each tile is ingests into it's own layer, and the resulting map consists of layers which consist of combinations of differently-weighted source layers (a weighted overlay).

API routes:

• gt/colors - Color Ramps
• gt/breaks - Color Breaks
• gt/tms/{zoom}/{x}/{y} - Weighted Overlay
• gt/sum - Zonal Summary

Color Ramps

List of available color ramps to color weighted overlay:

• blue-to-orange
• green-to-orange
• blue-to-red
• green-to-red-orange
• light-to-dark-sunset
• light-to-dark-green
• yellow-to-red-heatmap
• blue-to-yellow-to-red-heatmap
• dark-red-to-yellow-heatmap
• purple-to-dark-purple-to-white-heatmap
• bold-land-use-qualitative
• muted-terrain-qualitative

Color Breaks

Get Parameters: layers, weights, numBreaks.

Calculates breaks for combined layers by weights with specified breaks amount.

Weighted Overlay:

Get Parameters: layers, weights, breaks, bbox, colors: [default: 4], colorRamp: [default: "blue-to-red"], mask.

It is a TMS layer service that gets {zoom}/{x}/{y}, passed a series of layer names and weights, and returns PNG TMS tiles of the weighted overlay. It also takes the breaks that were computed using the gt/breaks service. If the mask option is set to a polygon, {zoom}/{x}/{y} tiles masked by that polygon would be returned.

Zonal Summary:

Get Parameters: polygon, layers, weights.

This service takes layers, weights and a polygon. It will compute a weighted summary of the area under the polygon.

Running Demo with GeoDocker Cluster

Quick clarification:

• Ingest requires Spark usage.
• Server works without Spark (uses GeoTrellis Collections API).

This description is a bit more generic, and describes dependent Spark server run.

To compile and run this demo, we prepared an environment. To run cluster we have a slightly-modified docker-compose.yml file:

• To run cluster:

    docker-compose up

  To check that cluster is operating normally check the availability of these pages:

  • Hadoop http://localhost:50070/
  • Accumulo http://localhost:50095/
  • Spark http://localhost:8080/

  To check containers status is possible using following command:

  docker ps -a | grep geodocker

More information avaible in a GeoDocker cluster repo

• Install and run this demo using GeoDocker cluster

  • Modify application.conf (working conf example for GeoDocker cluster):

      geotrellis {
        port = 8777
        server.static-path = "../static"
        hostname = "spark-master"
        backend  = "accumulo"
      }
    
      accumulo {
        instance   = "accumulo"
        user       = "root"
        password   = "GisPwd"
        zookeepers = "zookeeper"
      }
    

  • Modify backend-profiles.json (working conf example for GeoDocker cluster):

      {
        "name": "accumulo-local",
        "type": "accumulo",
        "zookeepers": "zookeeper",
        "instance": "accumulo",
        "user": "root",
        "password": "GisPwd"
      }

  • Copy everything into spark master container:

      cd ./geotrellis
      ./sbt assembly
      docker exec geotrellischattademo_spark-master_1 mkdir -p /data/target/scala-2.10/
      docker cp target/scala-2.11/GeoTrellis-Tutorial-Project-assembly-0.1-SNAPSHOT.jar geotrellischattademo_spark-master_1:/data/target/scala-2.10/GeoTrellis-Tutorial-Project-assembly-0.1-SNAPSHOT.jar
      docker cp  ../static geotrellischattademo_spark-master_1:/static
      docker cp data/arg_wm/ geotrellischattademo_spark-master_1:/data/
      docker cp conf geotrellischattademo_spark-master_1:/data/
      docker cp ingest.sh geotrellischattademo_spark-master_1:/data/
      docker cp run-server.sh geotrellischattademo_spark-master_1:/data/

      docker exec -it geotrellischattademo_spark-master_1 bash
      cd /data/; make ingest  # to ingest data into accumulo
      cd /data/; make server  # to run the server

  This demo would be installed into /data directory, inside spark master container.