I think you're being unjustifiably uncharitable by accusing them of intentional fraud. I think they're just fooling themselves because they're carried away by their enthusiasm for what they've created, which is really pretty cool.
You don't need custom printers to print at 1200+ pixels per "inch". Most off-the-shelf inkjet printers and some laser printers can do it, though at high resolutions there's a serious tradeoff between precise color and precise position. https://news.ycombinator.com/item?id=27965938 points out that standard imagesetters are 2540 "dpi" (and they have been since the 01980s). Photographic processes routinely produce images with a resolution below 10μm (2540 "dpi") and, when desired, below 2μm (12700 "dpi"). I don't mean with some kind of super niche lab equipment; I mean Kodak point-and-shoot cameras with mass-market Kodachrome film. Metal machining routinely hits precisions of 25 μm (1000 "dpi") and has for a century and a half, sometimes using machines made out of junk using nothing but hand tools; when it matters, it gets down to 1 μm (25400 "dpi"), which is roughly the measuring repeatability of any old handheld micrometer. You can buy such a micrometer on eBay for US$30 https://www.ebay.com/itm/363415676100?hash=item549d4324c4:g:... though a quality one probably costs US$60 or more, even used.
What made Harrison's achievements with the diffraction-grating ruling engines 70 years ago remarkable was not that he could position the ruling engine in increments of 25 nanometers or better (a million dpi); that, and even 2-nanometer increments, had been achieved for small gratings about a century earlier. His achievement was maintaining a total error under 5 nanometers across a distance of over 200 mm during the weeks necessary to rule a full diffraction grating. (I think the Richardson Grating Lab still uses the Michelson ruling engine he overhauled in the 01940s, though with further improvements.)
Fraud? Huh? When they say that these maps are the “most detailed” in their marketing materials they clearly mean that they are using a digital elevation model with higher resolution than the ones used to create other similar images available for sale elsewhere. They obviously use relatively standard digital photo printing processes, and are not implying otherwise. If you have your own source file, you can get it printed/mounted using similar technology from your favorite commercial print shop.
One can certainly produce a higher resolution image using various technologies (as you say, a photographic negative potentially has very high resolution). But so what? I really have no idea why you are talking about micrometers, diffraction gratings, and so on.
I came here to tell you, kragen, that I am enjoying your zeros before 4-digit dates, your derision of old units, etc. Oh, that and your informative comments, of course.
Comments
I think you're being unjustifiably uncharitable by accusing them of intentional fraud. I think they're just fooling themselves because they're carried away by their enthusiasm for what they've created, which is really pretty cool.
You don't need custom printers to print at 1200+ pixels per "inch". Most off-the-shelf inkjet printers and some laser printers can do it, though at high resolutions there's a serious tradeoff between precise color and precise position. https://news.ycombinator.com/item?id=27965938 points out that standard imagesetters are 2540 "dpi" (and they have been since the 01980s). Photographic processes routinely produce images with a resolution below 10μm (2540 "dpi") and, when desired, below 2μm (12700 "dpi"). I don't mean with some kind of super niche lab equipment; I mean Kodak point-and-shoot cameras with mass-market Kodachrome film. Metal machining routinely hits precisions of 25 μm (1000 "dpi") and has for a century and a half, sometimes using machines made out of junk using nothing but hand tools; when it matters, it gets down to 1 μm (25400 "dpi"), which is roughly the measuring repeatability of any old handheld micrometer. You can buy such a micrometer on eBay for US$30 https://www.ebay.com/itm/363415676100?hash=item549d4324c4:g:... though a quality one probably costs US$60 or more, even used.
What made Harrison's achievements with the diffraction-grating ruling engines 70 years ago remarkable was not that he could position the ruling engine in increments of 25 nanometers or better (a million dpi); that, and even 2-nanometer increments, had been achieved for small gratings about a century earlier. His achievement was maintaining a total error under 5 nanometers across a distance of over 200 mm during the weeks necessary to rule a full diffraction grating. (I think the Richardson Grating Lab still uses the Michelson ruling engine he overhauled in the 01940s, though with further improvements.)
Fraud? Huh? When they say that these maps are the “most detailed” in their marketing materials they clearly mean that they are using a digital elevation model with higher resolution than the ones used to create other similar images available for sale elsewhere. They obviously use relatively standard digital photo printing processes, and are not implying otherwise. If you have your own source file, you can get it printed/mounted using similar technology from your favorite commercial print shop.
One can certainly produce a higher resolution image using various technologies (as you say, a photographic negative potentially has very high resolution). But so what? I really have no idea why you are talking about micrometers, diffraction gratings, and so on.
I came here to tell you, kragen, that I am enjoying your zeros before 4-digit dates, your derision of old units, etc. Oh, that and your informative comments, of course.