ImageMosaic example with Modis COG datasets¶

indexer.properties:¶

This contains the main configuration to index the datasets composing the ImageMosaic.

Cog=true
PropertyCollectors=TimestampFileNameExtractorSPI[timeregex](time)
TimeAttribute=time
Schema=*the_geom:Polygon,location:String,time:java.util.Date
CanBeEmpty=true
Name=modisvi

Relevant parts:

• Cog flag specifying that the ImageMosaic is a Mosaic of COG Datasets

• PropertyCollectors, TimeAttribute and Schema are used to define the ImageMosaic index columns and how to populate them

• CanBeEmpty allows to define an empty ImageMosaic. It will be populated afterwards

• Name is the name for this mosaic

timeregex.properties:¶

The previous indexer refers to a time dimension and the related time column in the index’s schema that will get populated by extracting the time value from the filename (the 8 digits, representing YEAR, MONTH, DAY) using the regex specified in the timeregex.properties file. An example of sample file for this collection as stored on the S3 bucket is 2018.01.01.tif so the time regex will reflect that. Note the 3 groups of digits and the ‘format’ of the date.

. literalinclude:: src/modisvi/timeregex.properties

datastore.properties:¶

Due to the amount of available datasets, storing the ImageMosaic index on a DBMS is recommended, i.e. a PostGIS DB. See datastore.properties section of the ImageMosaic documentation for more info. Make sure that a DB with the name reported in the datastore is available

user=postgres
port=5432
passwd=postgres
url=jdbc\:postgresql\:modisvi
host=localhost
database=modisvi
driver=org.postgresql.Driver
schema=public
SPI=org.geotools.data.postgis.PostgisNGDataStoreFactory
fetch\ size=1000
max\ connections=20
min\ connections=5
validate\ connections=true
Loose\ bbox=true
Expose\ primary\ key=false
Max\ open\ prepared\ statements=50
preparedStatements=false
Estimated\ extends=false
Connection\ timeout=20

Once the 3 files have been setup, create a zip archive with them and let’s name it modisvi.zip. (Note that the files need to be in the root of the zip files, not into a subdirectory)

You are now ready to use REST calls to start the ImageMosaic creation.

ImageMosaic REST operations¶

On the next steps we assume:

• An existing GeoServer instance is running on port 8080 of localhost.

• A workspace named “test” exists on that GeoServer.

• REST credentials are user=admin password=geoserver.

• A default aws region is defined on JAVA System Property, using the flag -Diio.https.aws.region=us-west-2.

Make sure to update the incoming URLs accordingly, based on your actual installation.

Create an empty ImageMosaic without configuring it

curl -u admin:geoserver -XPUT --write-out %{http_code} -H "Content-type:application/zip" --data-binary @modisvi.zip http://localhost:8080/geoserver/rest/workspaces/test/coveragestores/modisvi/file.imagemosaic?configure=none

Response

201 OK

Providing sample prototyping granules

Next step is providing a prototype dataset for the coverage to be supported.

curl -u admin:geoserver -XPOST -H "Content-type: text/plain" --write-out %{http_code} -d "https://modis-vi-nasa.s3-us-west-2.amazonaws.com/MOD13A1.006/2018.01.01.tif" "http://localhost:8080/geoserver/rest/workspaces/test/coveragestores/modisvi/remote.imagemosaic"

Response

202 Accepted

Initializing the store (Listing available coverages)

Once a prototype has been provided we need to initialize the store by querying it for the available coverages.

curl -v -u admin:geoserver -XGET http://localhost:8080/geoserver/rest/workspaces/test/coveragestores/modisvi/coverages.xml?list=all

Response

<List>
  <coverageName>modisvi</coverageName>
</list>

Configuring the coverage

Once we get the list of available coverages, we need to configure a coverage by sending the config through REST.

curl -v -u admin:geoserver -XPOST -H "Content-type: text/xml" -d @"coverage.xml" "http://localhost:8080/geoserver/rest/workspaces/test/coveragestores/modisvi/coverages"

where coverage.xml has this content:

<coverage>
  <name>modisvi</name>
  <nativeName>modisvi</nativeName>
  <enabled>true</enabled>
  <metadata>
    <entry key="time">
      <dimensionInfo>
        <enabled>true</enabled>
        <presentation>LIST</presentation>
        <units>ISO8601</units>
        <defaultValue>
          <strategy>MAXIMUM</strategy>
        </defaultValue>
      </dimensionInfo>
    </entry>
  </metadata>
</coverage>

Adding more granules

Now that we have a coverageStore ready and a coverage layer configured we can start adding more granules.

curl -u admin:geoserver -XPOST -H "Content-type: text/plain" --write-out %{http_code} -d "https://modis-vi-nasa.s3-us-west-2.amazonaws.com/MOD13A1.006/2018.01.17.tif" "http://localhost:8080/geoserver/rest/workspaces/test/coveragestores/modisvi/remote.imagemosaic"

Setting Style

That MODIS data has 2 bands representing (Normalized Difference Vegetation Index) (NDVI) and Enhanced Vegetation Index (EVI). Let’s add this ndvi.sld style to apply a proper colormap to the NDVI band (copy this content to a file named ndvi.sld to be used by the next REST call):

<StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:sld="http://www.opengis.net/sld" xmlns:gml="http://www.opengis.net/gml" xmlns:ogc="http://www.opengis.net/ogc" version="1.0.0">
  <NamedLayer>
    <Name>Default Styler</Name>
    <UserStyle>
      <Name>ndvi</Name>
      <Title>ndvi</Title>
      <FeatureTypeStyle>
        <Name>name</Name>
        <Rule>
          <RasterSymbolizer>
            <ChannelSelection>
              <GrayChannel>
                <SourceChannelName>1</SourceChannelName>
              </GrayChannel>
            </ChannelSelection>
            <ColorMap>
              <ColorMapEntry color="#000000" quantity="-1"/>
              <ColorMapEntry color="#0000ff" quantity="-0.75"/>
              <ColorMapEntry color="#ff00ff" quantity="-0.25"/>
              <ColorMapEntry color="#ff0000" quantity="0"/>
              <ColorMapEntry color="#ffff00" quantity="0.5"/>
              <ColorMapEntry color="#00ff00" quantity="1"/>
            </ColorMap>
            <ContrastEnhancement/>
          </RasterSymbolizer>
        </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

curl -v -u admin:geoserver -XPOST -H "Content-type: application/vnd.ogc.sld+xml" -d @ndvi.sld http://localhost:8080/geoserver/rest/styles

curl -v -u admin:geoserver -XPUT -H "Content-type: text/xml" -d "<layer><defaultStyle><name>ndvi</name></defaultStyle></layer>" http://localhost:8080/geoserver/rest/layers/modisvi.xml

Final preview¶

This is how a layer preview will looks like: