A sharper map, and aircraft that fade rather than blink out

Three things asked for, and a fourth found while doing them.

The map looked like a photograph of a map, and did so twice over.  The
window fetched at its own pixel size but for a box a third larger in each
direction -- the margin added to stop the ground blinking -- and then cut
the middle out, so every pixel was enlarged by two thirds.  It now asks
for enough pixels to cover the bigger box at the window's own detail.
Underneath that, both the window and the animation took the nearest source
pixel: the tile mosaic is commonly half again the size of the picture, so
most of every tile was thrown away and what survived was the aliasing.
Both now average the source pixels that fall in each output cell, done as
the difference of a running total rather than a loop.

An aircraft that goes quiet now fades instead of vanishing.  Taking it off
between one frame and the next says it stopped existing; fading says it
stopped talking, which is what happened.  It fades where it was last
actually seen and never along a reckoned track, because the reason for
giving up on it is that where it would be by now is a guess.  --fade sets
how long, and it is in the menu.  The window has alpha and fades smoothly;
an indexed picture cannot blend, so the animation gained a fourth ramp at
a seventh of full and fades in four steps, which at a second apart reads
as a fade.  A trail fades with the aircraft it belongs to, and the box
goes before the symbol does.

The aircraft's country of registration carries a flag now as well as the
two ends of its route, from the register where one answered and from the
address block otherwise.

And the fourth: the window's header counted an aircraft that had gone
quiet as overhead, which was saying more than had been heard.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg

packaging/make-man.py

@@ -728,10 +728,14 @@ cycles how much each box says, for a busy sky;
 turns the trails off,
 .B g
 the map underneath,
+.B [
+and
+.B ]
+its brightness,
 .B +
 and
 .B \-
-change the range and
+the range, and
 .B q
 closes it. Closing the window leaves exactly the files a passive capture
 leaves, because it is the same code with a different thing watching it: the
@@ -873,6 +877,29 @@ draws the tracks on their own,
 .BI \-\-tiles " URL"
 points at another server, and where there is no network and nothing cached
 the picture falls back to the plain grid.
+.PP
+An aircraft that goes quiet fades rather than vanishing: taking it off the
+picture between one frame and the next says it stopped existing, and fading it
+says it stopped talking, which is what happened. It fades where it was last
+actually seen and never along a reckoned track, since the reason for giving up
+on it is that where it would be by now is a guess.
+.BI \-\-fade " SECONDS"
+is how long that takes, and zero takes it away at once.
+.PP
+The map is averaged down to the size of the picture rather than point-sampled,
+so lettering and roads stay whole, and the window fetches enough pixels to
+cover its margin at full detail rather than enlarging what it has.
+.BI \-\-map\-brightness " PERCENT"
+is how far up its range the map is drawn: dark enough that the aircraft stay
+the brightest thing on the picture, light enough that a coastline can be made
+out, and which way to err depends on the screen.
+.PP
+Every aerodrome under the picture is marked, not only the ones being flown
+between \[em] a receiver hears aircraft over its own county, and the county's
+airports say where on the map you are looking. They come from the same map
+data the tiles are drawn from, asked once per area and kept for a month.
+.B \-\-no\-airports
+turns that off.
 .SH METERS AND SENSORS
 Two things on the ISM bands are worth naming rather than reporting as
 hexadecimal.