11
Wisecrack
150d

My God is map development insane. I had no idea.

For starters did you know there are a hundred different satellite map providers?

Just kidding, it's more than that.

Second there appears to be tens of thousands of people whos *entire* job is either analyzing map data, or making maps.
Hell this must be some people's whole *existence*. I am humbled.

I just got done grabbing basic land cover data for a neoscav style game spanning the u.s., when I came across the MRLC land cover data set.

One file was 17GB in size.

Worked out to 1px = 30 meters in their data set. I just need it at a one mile resolution, so I need it in 54px chunks, which I'll have to average, or find medians on, or do some sort of reduction.

Ecoregions.appspot.com actually has a pretty good data set but that's still manual. I ran it through gale and theres actually imperceptible thin line borders that share a separate *shade* of their region colors with the region itself, so I ran it through a mosaic effect, to remove the vast bulk of extraneous border colors, but I'll still have to hand remove the oceans if I go with image sources.

It's not that I havent done things involved like that before, naturally I'm insane. It's just involved.

The reason for editing out the oceans is because the oceans contain a metric boatload of shades of blue.
If I'm converting pixels to tiles, I have to break it down to one color per tile.
With the oceans, the boundary between the ocean and shore (not to mention depth information on the continental shelf) ends up sharing colors when I do a palette reduction, so that's a no-go. Of course I could build the palette bu hand, from sampling the map, and then just measure the distance of each sampled rgb color to that of every color in the palette, to see what color it primarily belongs to, but as it stands ecoregions coloring of the regions has some of them *really close* in rgb value as it is.

Now what I also could do is write a script to parse the shape files, construct polygons in sdl or love2d, and save it to a surface with simplified colors, and output that to bmp.

It's perfectly doable, but technically I'm on savings and supposed to be calling companies right now to see if I can get hired instead of being a bum :P

Comments
  • 7
    Suggestion for dealing with ocean, build a terrain map using topographical data and key using that. Some free terrain datasets https://www.opentopodata.org/
  • 1
    Admittedly, this is... More work...
  • 2
    Also, anything involving coordinate systems is a bit crazy. Having messed up more than one.
  • 2
    Actually that's not a bad idea at all.
    Api limitation would take ages on that site, but in theory, if I open the maps and align and scale them (so we get a roughly one to one correspondance between the pixels on each), then its striaghtforward to consume the one biome map, use the elevation map as a key, and then using PIL, copy and output only those source image pixels which would be above sea level.

    This of course wont work for death valley, but that'll be easy enough to fill in by hand. Lot quicker than hand editing the full map too.

    Thank you Atheist!
    Cant believe I didnt consider this before.
  • 3
    Think you can also host locally or get a free topographical dataset and parse (looks like their docs link to some), or just, yes match image sizes, key from that.
  • 2
    Soon as I heard "and I'll do this manually for data", I was like, "That sounds boring, how can we cheat..." 😂
  • 3
    @atheist beats building a full parser/renderer for 17gbs worth of shapefiles.
  • 5
    In the mid-90s I had a job converting 75 degree paper maps to digital maps for the government. I had a digitizing table with a janky mouse-like device that had magnetic wire crosshairs that I’d have to align with whatever feature I was mapping. Usually roads and boundary lines. Just pointing and clicking to make dot-to-dot sets of arcs that would translate to coordinate points in an ESRI Arc-GIS Oracle database. Then I had to write and run scripts to clean up the data for storing in a digital warehouse. It was time-consuming and tedious work. In the end I mapped millions of acres.
  • 5
    I graduated from a reputable maps school here in Nova Scotia, I didn’t take anything really related to Gis since I was in the programming course, but it’s really quite neat and way more involved than I had expected it to be.

    Maps are cool.
  • 2
    @stackodev that sounds like the coolest fucking job. Thank you for your blood sweat and tears.

    We've come a long way in some ways.
  • 1
    @TurtleTheDev holy shit, that's so far north you-re probably a viking.

    Maps really are cool.

    I'll mail you one so you can navigate and sail the ol' long boat down to my neck of the woods.
  • 3
    Talking of maps:

    https://en.wikipedia.org/wiki/...

    I'm also reminded of:

    https://lapintagalapagoscruise.com/...

    ----

    In 1929, the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as 1,852 meters.

    Imperial units and United States customary units used a definition of the nautical mile based on the Clarke (1866) Spheroid. The United States nautical mile was defined as 6,080.20 feet (1,853.24 m) based in the Mendenhall Order foot of 1893. It was abandoned in favor of the international nautical mile in 1954.

    The Imperial nautical mile, often called an Admiralty mile, or more correctly, an Admiralty measured mile, as defined by its relation to the Admiralty knot – 6,080 imperial feet per hour – so 1 imperial nautical mile is about 1,853.181 meters. It was abandoned in 1970 and, legally, references to the obsolete unit are now converted to 1,853 meters.

    ----
  • 2
    All this different naughtygal mile units, must play havoc when trying to work out old treasure maps !

    Amusingly, some museums have boxes full of treasure maps that no one has looked at for like hundreds of years..
  • 3
    @Wisecrack Thanks. I deeply regret not doing a separate contract which was getting on a 4-wheeler and driving out into the national forest to take GPS points of various roads. What a cool experience that would’ve been. I often wonder whether I would’ve enjoyed a GIS career more than this web dev career I’ve had for 25 years. I could’ve even gotten into the remote sensing industry and maybe even done some stuff with satellites with LiDAR and such.
  • 0
    @stackodev Is it too late to dream different dreams, dreams you dreamed so long ago?
  • 2
    @Wisecrack It feels like it. I’m older and getting weary of building any kind of career. Planning on trying to retire early and get more meaning out of life than a constant grind 8:30-5:30 job in anything at all. Maybe I’ll finally try to finish writing one of the many manuscripts I started over the years and become a published author.
  • 1
    @Nanos why are nautical 'miles' measured in meters though? Was it like the brits trying to assert themselves on their american cousins?
  • 1
    @Wisecrack

    No idea, all this different units for that and that in the same sphere, gets me confused.

    https://en.wikipedia.org/wiki/...

    https://en.wikipedia.org/wiki/...

    ----

    In typography, the point is the smallest unit of measure. It is used for measuring font size, leading, and other items on a printed page. The size of the point has varied throughout printing's history. Since the 18th century, the size of a point has been between 0.18 and 0.4 millimeters. Following the advent of desktop publishing in the 1980s and 1990s, digital printing has largely supplanted the letterpress printing and has established the DTP point (DeskTop Publishing point) as the de facto standard. The DTP point is defined as 1⁄72 of an international inch (1/72 × 25.4 mm ≈ 0.353 mm) and, as with earlier American point sizes, is considered to be 1⁄12 of a pica.

    ----

    All I remember is, 14+ points, or old folk can't read stuff !
  • 1
    @Nanos 14 pt is getting too small for me. I have progressive lenses and 16 is the most comfortable.
  • 0
    @stackodev

    I can just about read stuff on a 50" monitor without my glasses.

    I think I might need a 65" next upgrade cycle..

    I wonder if Covid might be making my eyesight worse..

    https://keckmedicine.org/blog/...

    https://aao.org/editors-choice/...

    https://livescience.com/severe-covi...
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