Today's random topic: Map archeology

Specifically I am talking about the BatMUD world map of the "new world" aka
"Age of Exiles" world, with the five major continents and all that.

All this was triggered by an off-hand rhetorical question from ?arppa on a
society channel. Our anonymous hero was curious whether there existed a
version of the world map without all the location / scenic markers.
This made me ponder about the issue, because there are actually several
different answers to that question, and none of them are exactly "correct".

0) The Prelude
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As the "map bunny", over the years I have developed various kinds of tools
to produce and maintain the "Pupumaps" which are the basis also for the
BatClient location data and Jeskko's fancy world map thingamabob.

While BatMUD publishes the current (aka updated once per boot) raw ASCII
maps on the web, those maps contain all the scenics, player city blocks
etc, embedded into them.

But with my tools, and having been around for a long time, I have been able
to keep "cleaner" base versions of the continent maps. They are not perfect,
because us mortals back then in late 2006 arrived to a new world which already
had been somewhat populated by areas. Not all of them, though. And at the
beginning, the raw maps were not available - we had to run or sail around
the world to construct the ASCII maps from 'map' blocks. It was a huge
undertaking and you can read some tidbits about the history from
https://tnsp.org/maps/faq.php#4

Summa summarum, I personally did not have the "pristine" new world continent
maps stashed anywhere. Not that I needed them, but the issue started to nag
me a bit...

1) The MUDdier side of things
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First of all, some technical background: in the game itself, the world map
(or maps, as each continent has a separate one), have the scenic markers in
the map data itself. When a new area or player city is placed with a scenic
marker in the outworld, the terrain in that room gets replaced by '?' (or
'%', 'C' or so on). For area scenics, the previous terrain for it is stored
in the area server. I haven't investigated what happens with pcity blocks.
The previous terrain seems to be used for some purposes if it is set.

However .. there are some scenics that seem to have been transplanted in
some manner that there is no previous terrain known. I do not know the exact
details, I was not there in the wizard-side of things when the transition
occured back in 2006.

This would make it seem that the original terrain data for those scenics
is permanently lost.

But .. obviously there was something there originally. Someone drew the
continent maps, and many of the areas were placed only after the fact ..
maybe they were stashed somewhere.

2) Holy investigation, BATman!
------------------------------
After wandering around the BatFilesystem(tm) for a while, I first managed
to find some remnants of what seemed to be pre-production versions of SOME
of the continent maps. Unfortunately most of them seemed to only exist in
image format like PPM and/or GIF. Also some of them were broken. There
were some non-working Python scripts for converting between PPM and ASCII
maps, both ways. After hacking together a working converter with some
error resilience I had something .. but it was not 100% good news.

Unfortunately the conversion made by those tools was "lossy", e.g. the
PPM/GIF files used same color values for some terrain/tile types that
should've been differentiated, thus making it impossible to recover all
the data (mainly the road types were not differentiable, e.g. | \ / + -)

While I pondered if this would be enough for reconstructing the original
states from my data and the partial recovered maps, I had a brainwave.

What if there are other relevant copies around?

Sure enough. One of the architects of the new world, Melemkor had some
copies around in his directories and after some investigation I found what
I believe are _almost_ the pristine continent maps before scenics etc.
had been placed on them.

I say "almost", because there are few scenic markers there already. These
files are timestamped 19 May 2006, about 6 months before the transition to
the new world occured in December of 2006.

3) Towards incoherent non-conclusions
-------------------------------------
Well, we have the mostly "pristine" original map data now .. are we done?
It's not that simple. The continents have changed several times during the
last 20 years, also in ways other than new scenics or player cities.
There have been various adjustments like adding new pieces of roads,
trails, and other geographical features. Creating "pristine" versions
of the continent maps that are up to date with current state of things
would require some work to combine the relevant changes.

This finally brings us to the heart of the problem. As I mentioned above
in the "MUDdier side of things", scenic placement can be "destructive".
While we probably can (and I probably will at some point) reconstruct
a up-to-date version of "pristine" continent maps - as much as that is
possible because of the potential unknowns - it leaves us with the
dilemma: It is entirely possible that there exist locations where it
is ambiguous what acutally SHOULD be there.

Maybe the original 2006 map has been changed in that place but after that
something has been placed there "destructively". And let us assume that
for this problem case my "cleaned" version does not have the answer either.

That leaves us with guessing. The point is somewhat moot in any case, as
when a scenic marker (or pcity) is removed, the terrain could be replaced
with anything. So maybe there is no right or wrong answer to be found? :)

Perhaps unsatisfactory, but that's life.