Make clusters look better by averaging locations of clustered points

README.md

@@ -218,7 +218,7 @@ tippecanoe -z5 -o filtered.mbtiles -j '{ "ne_10m_admin_0_countries": [ "all", [
    compensate for the larger marker, or `-Bf`*number* to allow at most *number* features in the densest tile.
  * `-al` or `--drop-lines`: Let "dot" dropping at lower zooms apply to lines too
  * `-ap` or `--drop-polygons`: Let "dot" dropping at lower zooms apply to polygons too
- * `-K` _distance_ or `--cluster-distance=`_distance_: Cluster points (as with `--cluster-densest-as-needed`, but without the experimental discovery process) that are approximately within _distance_ of each other. The units are tile coordinates within a nominally 256-pixel tile, so the maximum value of 255 allows only one feature per tile. Values around 20 are probably appropriate for typical marker sizes.
+ * `-K` _distance_ or `--cluster-distance=`_distance_: Cluster points (as with `--cluster-densest-as-needed`, but without the experimental discovery process) that are approximately within _distance_ of each other. The units are tile coordinates within a nominally 256-pixel tile, so the maximum value of 255 allows only one feature per tile. Values around 10 are probably appropriate for typical marker sizes. See `--cluster-densest-as-needed` below for behavior.
 
 ### Dropping a fraction of features to keep under tile size limits
 
@@ -229,7 +229,7 @@ tippecanoe -z5 -o filtered.mbtiles -j '{ "ne_10m_admin_0_countries": [ "all", [
  * `-aD` or `--coalesce-densest-as-needed`: Dynamically combine the densest features from each zoom level into other nearby features to keep large tiles under the 500K size limit. (Again, mostly useful for polygons.)
  * `-aS` or `--coalesce-fraction-as-needed`: Dynamically combine a fraction of features from each zoom level into other nearby features to keep large tiles under the 500K size limit. (Again, mostly useful for polygons.)
  * `-pd` or `--force-feature-limit`: Dynamically drop some fraction of features from large tiles to keep them under the 500K size limit. It will probably look ugly at the tile boundaries. (This is like `-ad` but applies to each tile individually, not to the entire zoom level.) You probably don't want to use this.
- * `-aC` or `--cluster-densest-as-needed`: If a tile is too large, try to reduce its size by increasing the minimum spacing between features, and leaving one placeholder feature from each group.  The remaining feature will be given a `"cluster": true` attribute to indicate that it represents a cluster, a `"point_count"` attribute to indicate the number of features that were clustered into it, and a `"sqrt_point_count"` attribute to indicate the relative width of a feature to represent the cluster.
+ * `-aC` or `--cluster-densest-as-needed`: If a tile is too large, try to reduce its size by increasing the minimum spacing between features, and leaving one placeholder feature from each group.  The remaining feature will be given a `"cluster": true` attribute to indicate that it represents a cluster, a `"point_count"` attribute to indicate the number of features that were clustered into it, and a `"sqrt_point_count"` attribute to indicate the relative width of a feature to represent the cluster. If the features being clustered are points, the representative feature will be located at the average of the original points' locations; otherwise, one of the original features will be left as the representative.
 
 ### Dropping tightly overlapping features
 
@@ -309,7 +309,7 @@ The postfilter receives the features at tile resolution, after simplification, c
 
 The layer name is provided as part of the `tippecanoe` element of the feature and must be passed through
 to keep the feature in its correct layer. In the case of the prefilter, the `tippecanoe` element may also
-contain `index`, `sequence`, and `extent` elements, which must be passed through for internal operations like
+contain `index`, `sequence`, `extent`, and `dropped`, elements, which must be passed through for internal operations like
 `--drop-densest-as-needed`, `--drop-smallest-as-needed`, and `--preserve-input-order` to work.
 
 #### Examples: