This satellite and LIDAR can see inside forests

Amazing stuff! What little we still know about our forests and oceans!

Global warming is a hoax and climate change is a religion!

(3) This satellite can see inside forests | BBC News - YouTube

An ancient civilization of 1-3 millions once flourished in the Amazonia

Amazing stuff!

"The first hint that sprawling ancient populations once occupied the Amazon rainforest in Brazil was found through the most mundane of happenstances. More than 20 years ago, geographer Alceu Ranzi, now at the University of Acre, sat on the right side of a plane flying over the ocean of green. Looking down, he saw a perfect circle inscribed on the ground, an unnatural shape produced only, he felt certain, by humans. He was right.

Decades of subsequent research ... have slowly revealed remnants of peoples that occupied even the forest’s most remote areas. ... what archaeologists call earthworks—a type of architecture carved into the landscape. Now, using a laser-based form of radar known as lidar, researchers suggest ancient Amazonians were widespread in territories previously considered uninhabited. ...

The area surveyed by the researchers cuts through Acre and Amazonas, two northern Brazilian states that border Venezuela, Colombia, Peru, and Bolivia. Although scientists already knew there were earthworks in the region, the new study delineated the western and northern borders of the geoglyph-building society, which researchers had previously named Aquiry. Far away from any major rivers, which historically sustained thriving populations, the scientists did not expect the Aquiry to reach such high numbers. ...

The team identified most of the earthworks in the new study as geoglyphs, ditches made in the ground that form geometric shapes including squares and circles, as well as more complex shapes such as pentagrams and octagons. Some are even more sophisticated, combining, for example, circles inside a perfect square. ..."

From the abstract:

"Numerous geometric earthworks have been found in southwestern Amazonia, evidence of a monument-building precolonial civilization. This knowledge has contributed to the discussion about the deep history and the precolonial urbanism of Amazonia, its sociocultural contexts and its environmental legacy.

Estimates of the geographical extent and population size of the forest civilization have remained weak, because the detection of earthworks has been almost exclusively limited to deforested areas where vegetation does not completely hide the structures.

Here we used canopy-penetrating LiDAR data over 4,430 km of flight to define the geographical distribution and quantity of earthworks in this region better. On the basis of both existing data and our LiDAR documentation, we show that this cultural area alone contains as many earthworks as previously estimated for the whole of Amazonia.

We also propose that the total human population of the area in 100–300 ad was 1.25–3 million people.

If similar results are found elsewhere in Amazonia, the total precolonial population density and its effect on the current Amazonian soil and forest structure, biodiversity and even some modelling of the global climate should be re-evaluated."

An ancient civilization of millions once flourished in the Amazon

Odd shapes hidden in dense Amazon rainforest reveal sprawling ancient civilization "Newly found earthworks suggest about 3 million people might have lived in just about 3% of the forest’s entire area"

Over 20,000 precolonial earthworks in the Southwest Amazonia (open access)

An aerial shot shows a square-shaped geoglyph in Acre, a state at Brazil’s northern border

Lidar uses infrared light to uncover the shapes hidden underneath dense tree canopies.

Fig. 2: Diverse earthwork types with their topographical contexts.

Fig. 1: Map of the study area.

Photonics advance could enable compact, high-performance lidar sensors with no moving parts

Good news!

"... A new study from ... researchers could help to enable next-generation lidar sensors that are compact, durable, and have no moving parts. The key advance is a novel design for a silicon-photonics chip, which is a semiconductor device that manipulates light rather than electricity.  ...

To avoid these drawbacks, the ... researchers designed and demonstrated an array of integrated antennas that minimizes unwanted crosstalk between the antennas. Their innovation allows a lidar chip to scan a wider field of view while maintaining low-noise operation compared to other silicon-photonics-based approaches. ..."

From the abstract:

"Integrated optical phased arrays (OPAs) have emerged as a promising technology for many applications due to their ability to dynamically control free-space optical beams in a compact and non-mechanical manner.

However, these integrated OPAs typically have a restricted field of view (FOV), limited by grating lobes caused by large antenna pitches that are typically necessary to reduce crosstalk between the antennas in the integrated OPA.

In this work, we develop and experimentally demonstrate for the first time, to the best of our knowledge, a set of integrated grating-based antennas with significantly-reduced inter-antenna crosstalk that enable half-wavelength-pitch integrated OPAs with grating-lobe-free and wide-FOV functionality.

First, we derive a generalized theoretical model to describe the coupling dynamics between lossy modes in a system and use this model to analyze the coupling between antennas.

Next, we design and demonstrate a set of three integrated grating-based antennas with different propagation coefficients to enable reduced inter-antenna crosstalk, successfully measuring a significant reduction from 100% to 1% coupling.

Finally, using these reduced-crosstalk antennas, we develop and demonstrate a half-wavelength-pitch integrated OPA, successfully demonstrating grating-lobe-free and wide-FOV functionality.

This work facilitates new functionality for high-performance integrated OPAs."

Photonics advance could enable compact, high-performance lidar sensors | MIT News | Massachusetts Institute of Technology "With a novel design, MIT researchers overcame a stubborn problem that has limited the effectiveness of chip-based systems for lidar."

Reduced-crosstalk antennas for grating-lobe-free and wide-field-of-view integrated optical phased arrays (open access)

Fig. 1: Wide-FOV integrated-OPA concept.

Fig. 2: Design of reduced-crosstalk antennas.

Jelena Notaros, senior author (Source)

Sub-$200 Lidar Could be installed in every car

Good news!

"MicroVision, a solid-state sensor technology company located in Redmond, Wash., says it has designed a solid-state automotive lidar sensor intended to reach production pricing below US $200. That’s less than half of typical prices now, and it’s not even the full extent of the company’s ambition. The company says its longer-term goal is $100 per unit. MicroVision’s claim, which, if realized, would place lidar within reach of advanced driver-assistance systems (ADAS) rather than limiting it to high-end autonomous vehicle programs. Lidar’s limited market penetration comes down to one issue: cost. ..."

Low-Cost Solid State Lidar Aims for ADAS Integration - IEEE Spectrum "MicroVision says its sensor could one day break the $100 barrier"

MicroVision hopes to produce a lidar unit costing under US $200—half of typical prices today.

Cheap Lidar on a Chip Puts Self-Driving Cars in the Fast Lane

Good news!

"... We expect to be turning our creations into actual products and producing large numbers of samples for the automotive industry in 2025.

We are currently working on two different versions of our lidar: a long-range version intended to be mounted at the front of the car for use at highway speeds and a short-range version with a wider field of view to provide complete coverage all around the vehicle. The two sensors have different optical phased arrays in their photonic ICs, while sharing the same back-end signal processing.

We expect that relatively low-cost lidar sensors from some of our competitors, such as Cepton and Luminar, will begin showing up in some top-of-the line cars as early as next year. ..."

Lidar on a Chip Puts Self-Driving Cars in the Fast Lane - IEEE Spectrum Commercial sensors will be reliable, tiny, and affordable

The authors’ lidar consists of two parts: a silicon photonic chip and a semiconductor chip [electron micrograph at left]. The latter contains the electronics that control the many photonic elements. A higher-magnification micrograph details the tiny copper bumps that are used to make the electrical connections between these two chips [right].

MIT Spinoff Building New Solid-State Lidar-on-a-Chip System

Recommendable! Comprehensive overview article on Lidar!

What is the challenge?

"The fully autonomous vehicles application space highlights the performance and development challenges facing the lidar industry. These requirements include
cost on the order of US $100 per unit,
ranging greater than 200 meters at 10 percent object reflectivity,
a minimum field of view (FOV) of 120° horizontal by 20° vertical, 0.1° angular resolution,
at least 10 frames per second with approximately 100,000 pixels per frame, and
scalable manufacturing (millions of units per year). ...
However, before lidar can be widely used by autonomous vehicles and robots, lidar units need to be manufacturable at large volumes, have high performance, and cost two orders of magnitude less than current commercial systems, which cost several thousands of dollars apiece. ..."

MIT Spinoff Building New Solid-State Lidar-on-a-Chip System - IEEE Spectrum Our team at Kyber Photonics is developing a lidar chip to enable the next generation of autonomous robots and vehicles