Dan Q

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My Geo*ing Limits

I thought it might be fun to try to map the limits of my geocaching/geohashing. That is, to draw the smallest possible convex polygon that surrounds all of the geocaches I’ve found and geohashpoints I’ve successfully visited.

World map showing the outer extent of the areas in which Dan has geocached/geohashed. A shaded polygon covers the UK (except the far North of Scotland), parts of California, Cape Town, and parts of Italy and Austria.

Mathematically, such a shape is a convex hull – the smallest polygon encircling a set of points without concavity. Here’s how I made it:

1. Extract all the longitude/latitude pairs for every successful geocaching find and geohashpoint expedition. I keep them in my blog database, so I was able to use some SQL to fetch them: 

SELECT DISTINCT coord_lon.meta_value lon, coord_lat.meta_value lat
FROM wp_posts
LEFT JOIN wp_postmeta expedition_result ON wp_posts.ID = expedition_result.post_id AND expedition_result.meta_key = 'checkin_type'
LEFT JOIN wp_postmeta coord_lat ON wp_posts.ID = coord_lat.post_id AND coord_lat.meta_key = 'checkin_latitude'
LEFT JOIN wp_postmeta coord_lon ON wp_posts.ID = coord_lon.post_id AND coord_lon.meta_key = 'checkin_longitude'
LEFT JOIN wp_term_relationships ON wp_posts.ID = wp_term_relationships.object_id
LEFT JOIN wp_term_taxonomy ON wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id
LEFT JOIN wp_terms ON wp_term_taxonomy.term_id = wp_terms.term_id
WHERE wp_posts.post_type = 'post' AND wp_posts.post_status = 'publish'
AND wp_term_taxonomy.taxonomy = 'kind'
AND wp_terms.slug = 'checkin'
AND expedition_result.meta_value IN ('Found it', 'found', 'coordinates reached', 'Attended');

2. Next, I determine the convex hull of these points. There are an interesting variety of algorithms for this so I adapted the Monotone Chain approach (there are convenient implementations in many languages). The algorithm seems pretty efficient, although that doesn’t matter much to me because I’m caching the results for a fortnight.

Animation showing an algorithm draw lines from point to point, selecting each point by avoiding counter-clockwise turns.
I watched way too many animations of different convex hull algorithms before selecting this one… pretty-much arbitrarily.

3. Finally, I push the hull coordinates into Geoapify, who provide mapping services to me. My full source code is available.

An up-to-date (well, no-more than two weeks outdated) version of the map appears on my geo* stats page. I don’t often get to go caching/hashing outside the bounds already-depicted, but I’m excited to try to find opportunities to push the boundaries outwards as I continue to explore the world!

(I could, I suppose, try to draw a second larger area of places I’ve visited: the difference between the smaller and larger areas would represent all of the opportunities I’d missed to find a hashpoint!)

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you are a printer we are all printers

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

…

Anyway, here’s the best printer for 2024: a Brother laser printer. You can just pick any one you like; I have one with a sheet feeder and one without a sheet feeder. Both of them have reliably printed return labels and random forms and pictures for my kid to color for years now, and I have never purchased replacement toner for either one. Neither has fallen off the WiFi or insisted I sign up for an ink-related hostage situation or required me to consider the ongoing schemes of HP executives who seem determined to make people hate a legendary brand with straightforward cash grabs and weird DRM ideas.

…

It’s sort-of alarming that Brother are the only big player in the printer space who subscribe to a philosophy of “don’t treat the customers like livestock”. Presumably all it’d take is a board-level decision to flip the switch from “not evil” to “evil” and we’d lose something valuable. Thankfully, for now at least, they still clearly see the value of the positive marketing the world gives them. Positive marketing like like this article.

The article is excellent, by the way. I know that I’m “supposed” to stir up hatred about the fact that its conclusion is written by an AI but… well, just read it for yourself and you’ll see why I don’t mind even one bit. Top notch reporting. Consider following the links within it to stories about how other printer manufacturers continue to show exactly how shitty they can be.

I recommended a Brother printer to the Vagina Museum the other month. I assume it ‘s still working out fine for them (and not ripping them off, spying on them, and/or contributing to the destruction of the the planet).

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A Proper Cup of Tea

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Screenshot from "A Proper Cup of Tea", showing the start of the game.

This “choose your own adventure”-style game about making the perfect cup of tea is just… excellent.

If you lack the imagination to understand how a game like this could have dozens of possible endings, you desperately need to play it. My favourite path so far through the game was to add a teabag, then hot water, then remove the teabag, then add some milk, then add a second teabag, then drink it.

Genuinely can’t stop laughing at this masterpiece.

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April Features!

I’m testing a handful of highly-experimental new features on my personal website using multivariate (“A/B”) testing.

Screenshot of the recent "Quickly Solving JigsawExplorer Puzzles" blog post with a new "Dark mode" switch hovering over it.
“Dark Mode” is just one of the new features I’m testing out.

If you visit within the next day or so you’re likely to be randomly-selected to try out one of them. (If you’re not selected, you can manually enable one of the experiments.)

I’d love to hear your feedback on these Very Serious New Features! Let me know which one(s) you see and whether you think they should become permanent fixtures on my site.

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Aberystwyth 1984

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Nigel Lowrie

This promotional video for Aberystwyth University has been kindly archived onto YouTube by one of the undergraduate students who features in it. It was produced in 1984; approximately the same time I first visited Aberystwyth, although it would take until fifteen years later in 1999 for me to become a student there myself.

But the thing is… this 1984 video, shot on VHS in 1984, could absolutely be mistaken at-a-glance for a video shot on an early digital video camera a decade and a half later. The pace of change in Aberystwyth was and is glacial; somehow even the fashion and music seen in Pier Pressure in the video could pass for late-90s!

Anyway: I found the entire video amazingly nostalgic in spite of how far it predates my attendance of the University! Amazing.

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Better In Our App

What they say: “This site works better in our app.”

What they mean (optimistic): “We couldn’t be bothered to make a good website.”

What they mean (realistic): “We can track and monetise you better if we can coerce you into installing this.”

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Quickly Solving JigsawExplorer Puzzles

Background

I was contacted this week by a geocacher called Dominik who, like me, loves geocaching…. but hates it when the coordinates for a cache are hidden behind a virtual jigsaw puzzle.

A popular online jigsaw tool used by lazy geocache owners is Jigidi: I’ve come up with several techniques for bypassing their puzzles or at least making them easier.

Dominik had been looking at a geocache hidden last week in Eastern France and had discovered that it used JigsawExplorer, not Jigidi, to conceal the coordinates. Let’s take a look…

Unsolved approx. 1000 piece jigsaw puzzle.
Not just any puzzle; the geocache used an ~1000 piece puzzle! Ugh!

I experimented with a few ways to work-around the jigsaw, e.g. dramatically increasing the “snap range” so dragging a piece any distance would result in it jumping to a neighbour, and extracting original image URLs from localStorage. All were good, but none were perfect.

For a while, making pieces “snap” at any range seemed to be the best hacky workaround.

Then I realised that – unlike Jigidi, where there can be a congratulatory “completion message” (with e.g. geocache coordinates in) – in JigsawExplorer the prize is seeing the completed jigsaw.

Dialog box reading "This puzzle's box top preview is disabled for added challenge."
You can click a button to see the “box” of a jigsaw, but this can be disabled by the image uploader.

Let’s work on attacking that bit of functionality. After all: if we can bypass the “added challenge” we’ll be able to see the finished jigsaw and, therefore, the geocache coordinates. Like this:

Hackaround

Here’s how it’s done. Or keep reading if you just want to follow the instructions!
  1. Open a jigsaw and try the “box cover” button at the top. If you get the message “This puzzle’s box top preview is disabled for added challenge.”, carry on.
  2. Open your browser’s debug tools (F12) and navigate to the Sources tab.
  3. Find the jigex-prog.js file. Right-click and select Override Content (or Add Script Override).
  4. In the overridden version of the file, search for the string – e&&e.customMystery?tt.msgbox("This puzzle's box top preview is disabled for added challenge."): – this code checks if the puzzle has the “custom mystery” setting switched on and if so shows the message, otherwise (after the :) shows the box cover.
  5. Carefully delete that entire string. It’ll probably appear twice.
  6. Reload the page. Now the “box cover” button will work.

The moral, as always, might be: don’t put functionality into the client-side JavaScript if you don’t want the user to be able to bypass it.

Or maybe the moral is: if you’re going to make a puzzle geocache, put some work in and do something clever, original, and ideally with fieldwork rather than yet another low-effort “upload a picture and choose the highest number of jigsaw pieces to cut it into from the dropdown”.

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Oxford’s Area Code at OGN 57

Ever wondered why Oxford’s area code is 01865? The story is more-complicated than you’d think.

Modern desk telephone with an 01865 number (masked) and a keypad with letters on the buttons, 2=ABC through 9=WXYZ, with superimposed question marks between the two.
As a child, I was told that city STD codes were usually associated to the letters that appear on some telephones… but that wouldn’t make any sense for Oxford’s code!

I’ll share the story on my blog, of course. But before then, I’ll be telling it from the stage of the Jericho Tavern at 21:15 on Wednesday 17 April as my third(?) appearance at Oxford Geek Nights! So if you’re interested in learning about some of the quirks of UK telephone numbering history, I can guarantee that this party’s the only one to be at that Wednesday night!

Not your jam? That’s okay: there’s plenty of more-talented people than I who’ll be speaking, about subjects as diverse as quantum computing with QATboxen, bringing your D&D experience to stakeholder management (!), video games without screens, learnings from the Horizon scandal, and whatever Freyja Domville means by The Unreasonable Effectiveness of the Scientific Method (but I’m seriously excited by that title).

Oxford Geek Night logo

Anyway: I hope you’ll be coming along to Oxford Geek Nights 57 next month, if not to hear me witter on about the fossils in our telecommunications networks then to enjoy a beer and hear from the amazing speakers I’ll be sharing the stage with. The event’s always a blast, and I’m looking forward to seeing you there!

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The Road (Segment) Less Travelled

Map showing approximate location of Dan's house, on a set of rural roads that connect to the A40 in two different places, with the segment between the two relevant junctions marked.

There are two junctions at which I can join the A40 trunk road from my house. When I drive East, I use the Easternmost of the two; when I drive West, I use the Westernmost; but I almost never drive the stretch of road between them!

A few years ago I generated heatmaps of my movements based on my long-running personal location log and, indeed, it shows a “cool spot” along this section of road too:

Heatmap showing a "cool spot" on the road (segment) less-travelled.

It’s inevitable I suppose that there should exist a “road (segment) less-travelled” right on my doorstep, but it still feels strange. Like when you live near a tourist attraction that you never get around to visiting. Except instead of a tourist attraction, I live near a major highway I rarely use.

Maybe I’m missing out on something great. Probably the commuters who use that road to get into and out of Oxford don’t think so.

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Dan Q found GC2BHX9 C-130J Hercules

This checkin to GC2BHX9 C-130J Hercules reflects a geocaching.com log entry. See more of Dan's cache logs.

Found by the geohound and I after a brief battle with the first stinging nettles of the season. Owie! She and I came over from Stanton Harcourt this morning – from which we see plenty of Brize Nortons’ Hercules! – because many of our favourite local walks are waterlogged. Things are somewhat drier underfoot here, but after our walk through the fields the pup and I are still rather muddy! TFTC.

Home Page, 50% Off!

In August, I celebrated my blog – with its homepage weighing-in at a total of just 481kb – being admitted to Kev Quirk‘s 512kb club. 512kb club celebrates websites (often personal sites) whose homepage are neither “ultra minimal” or “link pages” but have a total size, including all assets, of under half a megabyte. It’s about making a commitment to a leaner, more-efficient Web.

My relatively-heavyweight homepage only just slipped in under the line. But, feeling inspired perhaps by some performance enhancements I’ve been planning this week at work, I decided to try to shave a little more off:

Now, at ~234kb, danq.me just beats the excellent gomakethings.com (it’s all those heavyweight fonts, Chris!).

Here’s what I changed:

  1. The “recent article” tiles are dynamically sized based on their number, type, and the visitor’s screen resolution. But apart from the top one they’re almost never very large. Using thumbnail images for the non-first tile shaved off almost 160kb.
Illustration showing how the smaller tiles only need thumbnail images.
You can see the difference, but it’s still acceptable to look at, I think.
  1. Not space-saving, but while I was in there I ensured that the first tile’s image – which almost-certainly comprises part of the Largest Contentful Paint – is never delivered with loading="lazy".
  2. I was providing a shortcut icon in .ico format (<link rel="shortcut icon" href="/_q23t/icons/favicon-16-32-48-64-128.ico" />), which is pretty redundant nowadays because all modern browsers (and even IE11) support .png icons. I was already providing .png and .svg versions, but it turns out that some browsers favour the one with the (harmful?) rel="shortcut icon" over rel="icon" if both are present, and .ico files are – being based on Windows Bitmaps – horrendously inefficient.

By getting under the 250kb threshold, I’ve jumped up a league from Blue Team to Orange Team, so that’s nice too. I can’t see a meaningful path from where I’m at to Green Team (under 100kb) though, so this level might have to suffice.

Last-minute additions:

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