Vector tiles buffer is used to include data that is just outside of the tile. This data is used to prevent border effects when rendering the geometries. It is currently [hardcoded to 5 pixels](https://github.com/elastic/elasticsearch/blob/de2781f98696c1e6cfad2b5bf46fe752a5e3edbb/x-pack/plugin/vector-tile/src/main/java/org/elasticsearch/xpack/vectortile/feature/FeatureFactory.java#L63) but it should probably need to be user configurable by adding a new property on the vector tiles API which can change the value.




x-pack/plugin/vector-tile/src/main/java/org/elasticsearch/xpack/vectortile/rest/VectorTileRequest.java
private GridType gridType = Defaults.GRID_TYPE;
    private int size = Defaults.SIZE;
    private int extent = Defaults.EXTENT;
    private List<MetricsAggregationBuilder<?, ?>> aggs = Defaults.AGGS;
    private List<FieldAndFormat> fields = Defaults.FETCH;
    private List<SortBuilder<?>> sortBuilders;
    private boolean exact_bounds = Defaults.EXACT_BOUNDS;
    private int trackTotalHitsUpTo = Defaults.TRACK_TOTAL_HITS_UP_TO;
    private VectorTileRequest(String[] indexes, String field, int z, int x, int y) {
        this.indexes = indexes;
        this.field = field;
        this.z = z;
        this.x = x;
        this.y = y;
        
        this.bbox = GeoTileUtils.toBoundingBox(x, y, z);
    }
    public String[] getIndexes() {
        return indexes;
    }
    public String getField() {
        return field;
    }
    public int getX() {
        return x;
    }
    public int getY() {
        return y;
    }
    public int getZ() {