GeoHashGridProcess.java

/**
 * This file is hereby placed into the Public Domain. This means anyone is
 * free to do whatever they wish with this file.
 */
package mil.nga.giat.process.elasticsearch;

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import org.geotools.coverage.grid.GridCoverage2D;
import org.geotools.coverage.processing.Operations;
import org.geotools.data.Query;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.filter.visitor.SimplifyingFilterVisitor;
import org.geotools.geometry.jts.ReferencedEnvelope;
import org.geotools.process.ProcessException;
import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.process.vector.VectorProcess;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.geotools.util.logging.Logging;
import org.opengis.coverage.grid.GridGeometry;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory;
import org.opengis.filter.expression.PropertyName;
import org.opengis.filter.spatial.BBOX;
import org.opengis.util.ProgressListener;

@DescribeProcess(title = "geoHashGridAgg", description = "Computes a grid from GeoHash grid aggregation buckets with values corresponding to doc_count values.")
public class GeoHashGridProcess implements VectorProcess {

    private final static Logger LOGGER = Logging.getLogger(GeoHashGridProcess.class);

    private final static FilterFactory FILTER_FACTORY = CommonFactoryFinder.getFilterFactory(null);

    public enum Strategy {

        BASIC(BasicGeoHashGrid.class),  
        METRIC(MetricGeoHashGrid.class),
        NESTED_AGG(NestedAggGeoHashGrid.class);

        private Class<? extends GeoHashGrid> clazz;

        private Strategy(Class<? extends GeoHashGrid> clazz) {
            this.clazz = clazz;
        }

        public GeoHashGrid createNewInstance() throws ReflectiveOperationException {
            return clazz.getConstructor().newInstance();
        }

    }

    @DescribeResult(name = "result", description = "Output raster")
    public GridCoverage2D execute(

            // process data
            @DescribeParameter(name = "data", description = "Input features") SimpleFeatureCollection obsFeatures,

            // process parameters
            @DescribeParameter(name = "pixelsPerCell", description = "Resolution used for upsampling (in pixels)", defaultValue="1", min = 1) Integer argPixelsPerCell,
            @DescribeParameter(name = "gridStrategy", description = "GeoHash grid strategy", defaultValue="Basic", min = 1) String gridStrategy,
            @DescribeParameter(name = "gridStrategyArgs", description = "Grid strategy arguments", min = 0) List<String> gridStrategyArgs,
            @DescribeParameter(name = "emptyCellValue", description = "Default cell value", min = 0) Float emptyCellValue,
            @DescribeParameter(name = "scaleMin", description = "Scale minimum", defaultValue="0") Float scaleMin,
            @DescribeParameter(name = "scaleMax", description = "Scale maximum", min = 0) Float scaleMax,
            @DescribeParameter(name = "useLog", description = "Whether to use log values (default=false)", defaultValue="false") Boolean useLog,

            // output image parameters
            @DescribeParameter(name = "outputBBOX", description = "Bounding box of the output") ReferencedEnvelope argOutputEnv,
            @DescribeParameter(name = "outputWidth", description = "Width of output raster in pixels") Integer argOutputWidth,
            @DescribeParameter(name = "outputHeight", description = "Height of output raster in pixels") Integer argOutputHeight,

            ProgressListener monitor) throws ProcessException {

        try {
            // construct and populate grid
            final GeoHashGrid geoHashGrid = Strategy.valueOf(gridStrategy.toUpperCase()).createNewInstance();
            geoHashGrid.setParams(gridStrategyArgs);
            geoHashGrid.setEmptyCellValue(emptyCellValue);
            geoHashGrid.setScale(new RasterScale(scaleMin, scaleMax, useLog));
            geoHashGrid.initalize(argOutputEnv, obsFeatures);
            // convert to grid coverage
            final GridCoverage2D nativeCoverage = geoHashGrid.toGridCoverage2D();

            // reproject
            final GridCoverage2D transformedCoverage = (GridCoverage2D) Operations.DEFAULT.resample(nativeCoverage, argOutputEnv.getCoordinateReferenceSystem()); 
            // upscale to approximate output resolution
            final GridCoverage2D scaledCoverage = GridCoverageUtil.scale(transformedCoverage, argOutputWidth*argPixelsPerCell, argOutputHeight*argPixelsPerCell);
            // crop (geohash grid envelope will always contain output bbox)
            final GridCoverage2D croppedCoverage = GridCoverageUtil.crop(scaledCoverage, argOutputEnv);
            return GridCoverageUtil.scale(croppedCoverage, argOutputWidth, argOutputHeight);
        } catch (Exception e) {
            throw new ProcessException("Error executing GeoHashGridProcess", e);
        }
    }

    public Query invertQuery(
            @DescribeParameter(name = "outputBBOX", description = "Georeferenced bounding box of the output") ReferencedEnvelope envelope,
            Query targetQuery, GridGeometry targetGridGeometry
            ) throws ProcessException {

        final BBOXRemovingFilterVisitor visitor = new BBOXRemovingFilterVisitor();
        Filter filter = (Filter) targetQuery.getFilter().accept(visitor, null);
        final String geometryName = visitor.getGeometryPropertyName();
        if (geometryName != null) {
            final BBOX bbox;
            try {
                if (envelope.getCoordinateReferenceSystem() != null) {
                    envelope = envelope.transform(DefaultGeographicCRS.WGS84,false);
                }
                bbox = FILTER_FACTORY.bbox(geometryName, envelope.getMinX(), envelope.getMinY(), envelope.getMaxX(), envelope.getMaxY(),  "EPSG:4326");
            } catch (Exception e) {
                throw new ProcessException("Unable to create bbox filter for feature source", e);
            }
            filter = (Filter) FILTER_FACTORY.and(filter, bbox).accept(new SimplifyingFilterVisitor(), null);
            targetQuery.setFilter(filter);
        }

        final List<PropertyName> properties = new ArrayList<>();
        properties.add(FILTER_FACTORY.property("_aggregation"));
        targetQuery.setProperties(properties);
        return targetQuery;
    }

}