Month: May 2016

Algorithms used in the Airborne Lidar Processing System (ALPS)

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The Airborne Lidar Processing System (ALPS) analyzes Experimental Advanced Airborne Research Lidar (EAARL) data—digitized laser-return waveforms, position, and attitude data—to derive point clouds of target surfaces. A full-waveform airborne lidar system, the EAARL seamlessly and simultaneously collects mixed environment data, including submerged, sub-aerial bare earth, and vegetation-covered topographies.

(A typical Airborne LiDAR system. Image Source)

ALPS uses three waveform target detection algorithms to determine target positions within a given waveform: centroid analysis, leading edge detection, and bottom detection using water-column backscatter modeling. The centroid analysis algorithm detects opaque hard surfaces. The leading edge algorithm detects topography beneath vegetation and shallow, submerged topography. The bottom detection algorithm uses water-column backscatter modeling for deeper submerged topography in turbid water.

The report describes slant range calculations and explains how ALPS uses laser range and orientation measurements to project measurement points into the Universal Transverse Mercator coordinate system. Parameters used for coordinate transformations in ALPS are described, as are Interactive Data Language-based methods for gridding EAARL point cloud data to derive digital elevation models. Noise reduction in point clouds through use of a random consensus filter is explained, and detailed pseudocode, mathematical equations, and Yorick source code accompany the report.


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La Nina and India’s monsoon

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Meteorologists have said El Nino – a warming of surface temperatures in the Pacific Ocean – led to a deficient monsoon in India last year. EL Nino, which translates to The Little Boy, has a sister called La Nina, which translates to The Little Girl. La Nina –a below-average cooling of sea surface temperatures in the Pacific Ocean – which will kick in this year, will bring cheer to India and is expected to deliver a better-than-average monsoon for the subcontinent.

(A typical scenerio of El Nino and La Nina Source. Check this Infographics)

Above average rainfall

Skymet Weather Services, a privately owned forecaster, recently predicted – with a margin of error of 4% – that the four months of monsoon beginning in June would yield 109% more rainfall than the LPA (long period average). On average, India receives 887 mm of rainfall, and a increase of 9% (966.83 mm) is considered to be ‘above average.’ An increase of 10% or more is considered to be ‘excess.

Early onset

Experts have revised an initial forecast, which predicted that La Niña would kick in this September-October. Now, they expect its onset to be around the same time as the onset of the Indian monsoon.

Lots of rain in August, September

Meteorologists predict that rainfall will be 13% below average in June, but 8% above average in July. The second half of the monsoon season will be significantly wetter than the first, with rainfall expected to be 13% above average in August, and 23% above average in September.


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Drones against natural disasters

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In June 2013, the Himalayan state of Uttarakhand experienced severe flooding and landslides, resulting in a catastrophic natural disaster. An Indo-Norwegian cooperation project now provides technical support for mitigating disasters in the state and beyond.

The Norwegian Geotechnical Institute (NGI) is a leading international centre for research and consulting within geosciences. It offers expertise on the behaviour of soil, rock and snow and their interaction with the natural and manmade environment.

Illustrative photo of a drone. 
Photo: Andrew Turner / Flickr.

(A typical drone)

With support from the Norwegian Embassy in New Delhi, NGI is currently assisting the Department of Science and Technology (DST), Government of India, in spearheading a national program for mitigating landslide disasters. NGI is involved in the Department’s efforts in the state of Uttarakhand. The Himalayan state experienced a catastrophic natural disaster in June 2013 when heavy rainfall and cloudburst caused landslides and flooding, resulting in more than 10.000 fatalities.

Under the Indo-Norwegian cooperation project, state-of-the-art technologies are being used for monitoring, predicting and mitigating landslide disasters. Online automatic weather stations and web cameras are monitoring a critical landslide area (Kunjethi) in Uttarakhand. In addition, drone technology is being used to map unstable hilly areas where landslides can occur. Advanced computer software prepares three-dimensional terrain models for evaluating slope stability.

A scientist from NGI visited India recently, to provide training to DST-supported institutions involved in the Indo-Norwegian project. Participants were trained in the use of drones for mapping hilly terrain and analyzing the data collected by the drone afterwards. A drone can map an area of 1 square kilometer up to a height of 1000 meters in just half an hour. Manual mapping of such scale takes almost a month. As part of the project, a drone has been donated to the National Geotechnical Facility. The Facility has been set up in Dehradun, with technical assistance from NGI.


India’s first-ever indigenous space shuttle RLV-TD launched successfully

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ISRO successfully flight tested India’s first winged body aerospace vehicle operating in hypersonic flight regime. In this experimental mission, the HS9 solid rocket booster carrying RLV-TD lifted off from the First Launch Pad at Satish Dhawan Space Centre, Sriharikota at 07:00hr IST.  After a successful flight of 91.1second, HS9 burn out occurred, following which both HS9 and RLV-TD mounted on its top coasted to a height of about 56 km. At that height, RLV-TD separated from HS9 booster and further ascended to a height of about 65km.

(The seven meter long test vehicle paves the way for the country to develop 
 its own reusable spacecraft. Image source )

From that peak altitude of 65 km, RLV-TD began its descent followed by atmospheric re-entry at around Mach 5 (five times the speed of sound). The vehicle’s Navigation, Guidance and Control system accurately steered the vehicle during this phase for safe descent. After successfully surviving a high temperatures of re-entry with the help of its Thermal Protection System (TPS), RLV-TD successfully glided down to the defined landing spot over Bay of Bengal, at a distance of about 450km from Sriharikota, thereby fulfilling its mission objectives. The vehicle was successfully tracked during its flight from ground stations at Sriharikota and a shipborne terminal. Total flight duration from launch to landing of this mission of the delta winged RLV-TD, lasted for about 770seconds.

In this flight, critical technologies such as autonomous navigation, guidance & control, reusable thermal protection system and re-entry mission management have been successfully validated.



FGI releases hyperspectral Terrestrial Laser Scanning dataset as open data

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Finnish Geospatial Research Institute (FGI) at the National Land Survey of Finland has released a hyperspectral Terrestrial Laser Scanning (TLS) dataset as open data. Each point in the laser scanning point cloud contains colour information from several different wavelengths. Ordinary laser scanners only contain colour information from one wavelength.

(Test area overview from a single scan.)

Unique data

The laser scanning point cloud dataset consists of 30 individual scans collected as a time series covering a 26-hour time frame. The data was collected in September 2013 using FGI’s hyperspectral laser scanner (FGI HSL), which has been developed and built at the FGI. Each point in the laser scanning point cloud carries information about its spatial location and intensities of seven separate wavelength channels. Currently, this dataset is the only one of its kind.

Dataset available via Etsin

The dataset is available via the Etsin research data finding service provided by the Finnish Ministry of Education and Culture. Datasets are provided in .laz format and published under the Creative Commons Attribution 4.0 International License (CC-BY-40).


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India should build its own space station

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India should actively get into building its own space station in the Low Earth Orbit (LEO) as its next space frontier since the time is opportune for this, M.Y.S. Prasad, who retired as director of the Satish Dhawan Space Centre (SDSC) said.


(Artistic rendition of ISS)

“It is time to look 10-15 years ahead rather than planning for incremental growth activities. Building our own space station will be beneficial on many counts and would also generate around 15,000 high-skilled jobs,”, he added.

He said the technology development needed for manned missions to Low Earth Orbit and space stations in Low Earth Orbit will enhance the knowledge and competence of the country’s space agency — Indian Space Research Organisation (ISRO) — and the industrial capacity of the country.

The research and development (R&D) activities in these areas need the evolution of re-entry technologies, life support systems, safe recovery systems, more reliable launch and spacecraft systems, long-term platforms operating in space for specialised experiments and others, Prasad remarked.

He said India should get into the development of a rocket that can carry 7.5 tonnes into a Geostationary Transfer Orbit (GTO) and 10 tonnes into Low Earth Orbit. The setting up of a space station will result in the development of orbit-docking technology which countries like the US, Russia and China now possess.

“Developing the necessary technology, building and maintaining the space station involve huge financial outlay. Human flight is what ISRO should look at,” Radhakrishnan said.


China launches Yaogen-30 high resolution remote sensing satellite

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The Chinese have launched the Yaogan-30 remote sensing satellite via a Long March (Chang Zheng) 2D (Y27) rocket on Sunday. The launch – from the from the Jiuquan Satellite Launch Center – took place at 02:43 UTC from the 603 Launch Platform at the LC43 Launch Complex.

            (Photo of Yaogen-30 launch)

As is usual for the Chinese media, this spacecraft is once again classed as a new remote sensing bird that will be used for scientific experiments, land survey, crop yield assessment, and disaster monitoring.

The Jiuquan Satellite Launch Center, in Ejin-Banner – a county in Alashan League of the Inner Mongolia Autonomous Region – was the first Chinese satellite launch center and is also known as the Shuang Cheng Tze launch center. The site includes a Technical Centre, two Launch Complexes, Mission Command and Control Centre, Launch Control Centre, propellant fuelling systems, tracking and communication systems, gas supply systems, weather forecast systems, and logistic support systems.

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