Try to clarify documentation

This commit is contained in:
Eric Fischer
2015-12-15 12:22:19 -08:00
parent fee8b33bc8
commit 8e2c20265f
2 changed files with 15 additions and 11 deletions
+10 -6
View File
@@ -71,11 +71,13 @@ specified, the files are all merged into the single named layer.
.SS Zoom levels and resolution
.RS
.IP \(bu 2
\-z \fIzoom\fP: Base (maxzoom) zoom level (default 14)
\-z \fIzoom\fP: Maxzoom: the highest zoom level for which tiles are generated (default 14)
.IP \(bu 2
\-Z \fIzoom\fP: Lowest (minzoom) zoom level (default 0)
\-Z \fIzoom\fP: Minzoom: the lowest zoom level for which tiles are generated (default 0)
.IP \(bu 2
\-d \fIdetail\fP: Detail at base zoom level (default 12, for tile resolution of 4096)
\-B \fIzoom\fP: Base zoom, the level at and above which all points are included in the tiles (default maxzoom)
.IP \(bu 2
\-d \fIdetail\fP: Detail at max zoom level (default 12, for tile resolution of 4096)
.IP \(bu 2
\-D \fIdetail\fP: Detail at lower zoom levels (default 12, for tile resolution of 4096)
.IP \(bu 2
@@ -95,7 +97,7 @@ specified, the files are all merged into the single named layer.
.SS Point simplification
.RS
.IP \(bu 2
\-r \fIrate\fP: Rate at which dots are dropped at lower zoom levels (default 2.5)
\-r \fIrate\fP: Rate at which dots are dropped at zoom levels below basezoom (default 2.5)
.IP \(bu 2
\-g \fIgamma\fP: Rate at which especially dense dots are dropped (default 0, for no effect). A gamma of 2 reduces the number of dots less than a pixel apart to the square root of their original number.
.RE
@@ -168,7 +170,7 @@ coordinated with the base zoom level and dot\-dropping rate. You can use this sh
calculate the appropriate marker\-width at high zoom levels to match the fraction of dots
that were dropped at low zoom levels.
.PP
If you used \fB\fC\-z\fR to change the base zoom level or \fB\fC\-r\fR to change the
If you used \fB\fC\-B\fR or \fB\fC\-z\fR to change the base zoom level or \fB\fC\-r\fR to change the
dot\-dropping rate, replace them in the \fB\fCbasezoom\fR and \fB\fCrate\fR below.
.PP
.RS
@@ -193,7 +195,9 @@ awk 'BEGIN {
At every zoom level, line and polygon features are subjected to Douglas\-Peucker
simplification to the resolution of the tile.
.PP
For point features, it drops 1/2.5 of the dots for each zoom level above the base.
For point features, it drops 1/2.5 of the dots for each zoom level above the
point base zoom (which is normally the same as the \fB\fC\-z\fR max zoom, but can be
a different zoom specified with \fB\fC\-B\fR if you have precise but sparse data).
I don't know why 2.5 is the appropriate number, but the densities of many different
data sets fall off at about this same rate. You can use \-r to specify a different rate.
.PP