Unmanned Aerial Vehicle (UAV), popularly known as Drone, is an airborne system or an aircraft operated remotely by a human operator or autonomously by an onboard computer. UAV based Remote Sensing (UAV-RS) is the new addition to the North Eastern Space Applications Centre (NE-SAC) for large-scale mapping and real time assessment and monitoring activities of various applications.

NE-SAC has taken the initiative for design and assembling of UAVs for various applications. Different components of the UAV are selected based on the design parameters (Table 1) and assembled as per the requirements. A Hex Copter was designed and assembled by NE-SAC, which can carry maximum payload up to 2.5 Kg of different sensors such as thermal, multispectral, optical, hyperspectral or LIDAR. The centre is also equipped with a Ready-to-fly Quad Copter with an integrated optical sensor, which can capture high-resolution geo-tagged aerial photos and high-definition videos.

In addition, NE-SAC has also indigenously developed a Fixed Wing UAV and the flight test was successfully carried out on November 01, 2016 at NE-SAC. The design parameters along with flight test results are given in the Table 2.

The multi rotor based UAV has been flown in different areas of NE states by NE-SAC as part of technology developmental activities. Few tests were made based on the demands from the respective District Administrations of NE region. Some of the important case studies made by the centre are highlighted below:

Mapping of Landslide Affected Area: Mapping of landslide affected area was taken at the request of District Disaster Management Authority of Nongpoh, Meghalaya. The NH-40 connecting Guwahati to Shillong city is considered to be the life line of Meghalaya State. A number of landslides had occurred there which caused loss of life and properties. 3D View of Landslide Infested Crop Damage Assessment: Naramari village of Morigaon District, Assam, India had been reported severe infestation of Boro Paddy by Brown Plant Hopper (BPH) insect. As per the request from officials from State Government of Assam, an UAV flight was conducted in the affected area and a total area of 0.55 sq. km was covered with a 15 minutes flight. Figure shows the categorisation of BPH infested rice fields. Infested Fields in Naramari Village, Morigaon District, Assam Categorisation of BPH Infested Rice Fields Large Scale Mapping of Nongpoh Town of Meghalaya: A flight was performed at 120 m height along the NH-40 for a period of 12 minutes covering an area of 0.84 Sq. Km. The image was acquired with a ground pixel resolution of 5 cms. Nongpoh Town as viewed from UAV Large Scale Land Use Map of Nongpoh Town 3-Dimensioinal Terrain Model Construction: The realistic and aesthetically pleasing 3D mesh models, accurate 3D models for volumetric analysis etc.,can be generated from the UAV imagery. Figure shows the 3D reconstruction of Municipal Urban Development Authority (MUDA) shopping complex of Nonghpoh town using the UAV images with a ground pixel resolution of 5 cms. 3D Reconstruction: MUDA Shopping Complex, Nongpoh

NE-SAC organised a two weeks advance course on "UAV Remote Sensing – Technological Advances and Applications", during October 31 – November 11, 2016 to provide in-depth understanding and knowledge in the field of UAV remote sensing and its relevant technologies and applications. A total of 26 participants from different parts of the country attended the training programme.

Operational Challenges and Issues

The imagery obtained from UAVs can immensely support in many applications ranging from large scale mapping, urban modelling to vegetation structure mapping. However, there are restrictions like – i) limitation in the size of the study area, ii) constraint in processing of large volume of data, iii) requirement of large scale processing and large storage space, etc. In addition, existing features capturing and extraction techniques need to be improved for processing of high dimensional UAV data. UAVs can perform efficient surveys for disaster prone or physically inaccessible areas, quick damage assessment of landslides, floods and earthquakes for enabling relief measures.

Table 1: Test Flight Results of Hex Copter

Sl. No. Design Criterion Design Parameter Test Flight Results 1 Payload capacity Up to 2.5 kgs A maximum of 1.5 kgs was tested 2 Flight endurance Up to 30 mins 15 mins for 1.5 kgs payload and 25 mins for GoPro/YI action camera (weight less than 100 gms) 3 Fly options Manual, GPS aided, Autonomous All tested successfully 4 Fly height Up to 2 Kms Tested up to 500 m which was good enough for required applications 5 Fly range Up to 2 Kms Tested up to 1.8 kms with clear line of sight

Table 2: Test Flight Results of Experimental Fixed Wing UAV

Sl. No. Design Criterion Design Parameter Test Flight Results 1 Payload capacity Up to 0.5 kgs A maximum of 0.2 kgs was tested 2 Flight endurance Up to 30 mins Tested up to 20 mins with 0.2 kgs of payload 3 Fly options Manual Tested successfully 4 Fly height Up to 0.5 Kms Tested up to 300 m 5 Fly range Up to 1 Kms Tested up to 0.5 kms with clear line of sight

The Customisable Hex Copter Ready to Fly Quad Copter

Flight Test of Fixed Wing UAV carried out successfully at NE-SAC