Lidar reveals urbanization and landscape modifications at ancient Maya city | Hacker News Reader

Lidar reveals urbanization and landscape modifications at ancient Maya city

ucalgary.ca

81 pointsmdp202123 comments

Original title: 'UCalgary research collaboration reveals new urbanization and landscape modifications at ancient Maya city // Lidar technology unearthed tropical megapolis beneath forest canopy of the Calakmul Biosphere'

Video presentation, 1hr, in Spanish (by the Instituto Nacional de Antropología e Historia, Mexico), at https://www.youtube.com/watch?v=m58Wjq9jRWY

Information about the use of LiDAR for archaeology can be found at https://education.nationalgeographic.org/resource/lidar-and-...

> Many of the buildings and artifacts of Mesoamerica's civilizations have been hidden by lush rainforest vegetation. Now the technology of LiDAR has helped archeologists to unearth these hidden gems

I see that a moderator rewrote my "cut" of the original title: thank you. I try to be conservative when I have to edit the titles (to avoid tampering as much as possible), so there will easily be better versions.

I was there at Calakmul in 2015. It was awe inspiring to see an ancient settlement in the middle of what is a remote site of today. We drove through several hours of dirt roads to get to the site, and the place was magnificent. Walking in the ruins felt like time travel because we could climb in the pyramids, imagine what their houses looked like from what remained, was told by the archeological info boards about what used to be a merchants gallery vs residential area etc. To imagine the life of the mayans was fascinating.

> To imagine the life of the mayans was fascinating.

The ancient Mayans. The life of todays Mayans is equally interesting. If you want to know how they live today, knock on the door of one of their houses and ask them. They'll probably cook you an excellent meal while describing their life. Most speak Spanish as their second language, and they're re-learning how to write their native language because the Spanish forced them to forget it (on pain of death).

Well worth visiting. The nearest town is probably 1.5 - 2 hours away from the main site. It is truly in the middle of nowhere. The pyramids are enormous and spectacular. Basically all of the site is shrouded in jungle. I do not think you can see the acropolis with surviving paintings but perhaps this has changed.

Also from the top of one pyramid you can see what looks like a mountain maybe 20 miles away in Guatemala. Very interesting and unusual for such a flat region! In fact it isn’t a mountain at all, but another pyramid at the (mostly unexcavated) El Mirador site in Guatemala. By some definitions, that other pyramid is the world’s largest. The calakmul pyramids are themselves enormous.

Cannot recommend the Mayan sites of the Yucatán highly enough. If you have only been to Tulum you are cheating yourself! Definitely worth a trip to Mexico!

Huh. I wonder if they used some kind of signaling to communicate with each other back in the day?

You forgot to mention the cenotes! That whole peninsula is underrated. We had entire pyramids to ourselves and this was before Covid.

https://en.wikipedia.org/wiki/1491:_New_Revelations_of_the_A...

An excellent book if this ancient America is interesting to you.

Several copies are in the Library of the Archive, such as:

https://archive.org/details/149100char

You are happily reminded that participation is free and anonymous.

Strongly second this recommendation. The book is eye-opening - you won't look at the western hemisphere the same way again.

I've recently read this book and would like to third this recommendation. Eminently readable and illuminating, a great joy. I look forward to reading his follow-up "1493" soon.

Very cool project, I misread that as "megalopolis" but I take it that a megapolis is a city with thousands of residents - 50K in the case of Calakmul[1], which is large for a premodern city, but only 1/4 the size of Tenochtitlan[2].

1: https://en.wikipedia.org/wiki/Calakmul#Population_and_extent

2: https://en.wikipedia.org/wiki/Tenochtitlan#History

Can anyone knowledgeable correct / confirm my understanding of why the Lidar technique works?

The Lidar is able to penetrate (or just get in between) gaps in foliage which otherwise obscure or smooth out the features on the ground / dirt-level. So then by taking the lowest ground surface height reached in a certain patch of ground scanned (like sq. ft) you're able to "see" the actual ground?

If so, why didn't radar work previously? Too long wavelength? Or that's like a continuous wave / average scan versus a point-by-point scan?

Thanks!

Radar does work, there's just a trade-off between frequency and resolution. LIDAR is way up in the near-optical regime, so it has very poor penetration but the resolution is so high that you can see the small gaps in the canopy. Importantly, you can also do fancy signal processing with the reflectance and multiband stuff to distinguish man-made objects from foilage. That's uncommon in the archaeology world (unless using data where that's already been done), but the military and commercial people take full advantage.

Good question.

> What makes lidar a better choice for many applications, including archaeology, is that the wavelength is about half a micron – tiny relative to radar wavelengths, which are measured in centimetres or decimetres. For details of a relatively small spot on the ground, lidar provides a precision that radar cannot match.

Source: https://www.theguardian.com/science/2015/jun/20/lidar-radar-...

Wengrow & Graeber’s Dawn of Everything is a fantastic read related to this

I went to Calakmul earlier this year - it's an awesome site. It's amazing that there may be yet much more to be discovered.

For the ones interested in the subject I recall the documentary "Lost Treasures of the Maya" (2018) was quite good. It's a four part doc about Maya and the discoveries made due to Lidar. It might still be available on D+

I use LiDar in the USA for finding places to metal detect.

Seems like an odd comnment - why and how?

Lidar ain't much use without an air platform .. and it will basically just give you topography; surface land shape, vegetation density and snowpack (with tweaks), etc.

If you're using an air platform and want to explore for metals .. why not go full EM and magnetic survey while you're there ...

Sure you're not an AI-bot saying silly things?

OP probably meant to say that he uses pre-made Lidar maps to scout locations where he is likely to find lost human artifacts. He's not looking for underground deposits, but trying to find things like long lost outlines of house foundations in the woods. The availability of these maps has made it much easier to find these. Instead of wandering blindly through the woods, you can go straight to a GPS location. It's a big thing in the metal detecting community, and he is not likely to be a bot. Here are some of the maps to check out if you are in the US: https://apps.nationalmap.gov/3depdem/.

> Sure you're not

Defrost, now assuming there did not exist an interpretation that makes that original comment sensible - and really, I can think of one (it is vague and does not matter now) -, now consider the several possible reasons one may say instances of what you call «silly things», starting from a very personal sense of humour to very possible, "very personal other states". Automation being just a very limited sector in the realm of possibilities. Now see the image of somebody calling a "bot" somebody else who may, in an important range of cases, struggling for their own reasons - a few of them also common to all of us, unless for example some Benjamin Button's syndrome had you born fully adult.

I myself had been called "a bot" in this pages for having written very, very valid, I grant you, pieces of data and instances of reasoning that some in the public could not understand and dismissed. Even the style I used for this post I can already tell you will trigger a "must be a bot" in some readers. Very "avoidable" responses.

Take the seconds required to make a list of why people may «say[] silly things», and see why it is not a good idea to call them a bot. If you really cannot figure out some trivial possibilities, I may mention some among us that could create Operating Systems and yet "struggled".

Edit (an addition):

Paradoxically, if you could not understand, in some "Voight-Kampff test" scenario, why it would be offensive to call a bot e.g. some "Nietzsche" behind the curtains, guess who the Bayesian needle would incline to suspect as a bot.

Interesting that the other comment on this account is also a short sentence that mentions a recreational pursuit (Pokémon GO) in the U.S

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