Current Science

R. Suraj Reddy ¹, Rakesh ¹, C. S. Jha ¹, K. S. Rajan ²

Affiliations
1 Forestry and Ecology Group, National Remote Sensing Centre, Hyderabad 500 037, IN
2 Lab of Spatial Informatics, Indian Institute of Information Technology, Hyderabad 500 032, IN

Abstract

Forest inventories are critical for effective management of forest resources. Recently, the use of terrestrial laser scanning (TLS) to automatically extract forest inventory parameters at tree level (e.g. tree location, diameter at breast height (DBH) and height) has gained significant importance. TLS using both single-scan and multi-scan techniques, not only helps in detailed and accurate measurements of tree objects but also helps increase the measurement frequency. In the current study, we develop an automated solution to extract forest inventory parameters at individual tree level from TLS data by using random sample consensus (RANSAC)-based circle fitting algorithm. The method was evaluated on both single- and multiscan data by characterizing four circular plots of radius 20 m in dry deciduous forests of Betul, Madhya Pradesh (India). Over all the plots, tree detection rates of 75% and 97% were obtained using single- and multi-scan TLS data respectively. Tree detection rates were significantly affected by increase in distance from the scanner, in single-scan approach when compared to multi-scan approach. Field based DBH measurements correlated well using both single (R² = 0.96) and multiple scans (R² = 0.99). The DBH estimates from multi-scan TLS data resulted in low ischolar_main-meansquare error (RMSE) of 2.2 cm compared to that of 4.1 cm using single-scan. Further, tree heights were extracted from TLS data and validated with selectively measured trees on field (R² = 0.98; N = 65). The RMSE of tree height was estimated to be 1.65 m. The current results show the potential use of TLS in automatically deriving forest inventory parameters with reliable accuracy at individual tree level.

Keywords

DBH, Forest Inventory Parameters, Multiscan, Single-Scan, Terrestrial Laser Scanner.

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K. S. Rajan ¹, S. Swaminathan ¹, S. Vaidhyasubramaniam ²

Affiliations
1 Centre for Nanotechnology & Advanced Biomaterials, SASTRA Deemed University, Thanjavur 613 401, IN
2 SASTRA Deemed University, Thanjavur 613 401, IN

Abstract

The publication output from Indian institutions has been steadily increasing during the last few years. This may be attributed to the higher investment in research and also linking the number of publications with career advancement. There is a need to analyse the publication output of Indian institutions in terms of quality of publications. In this study, output in the top 10 percentile, as computed by SciVal (a product of Elsevier), has been used as an indicator of the quality of research output, since it reflects the percentage of an institution’s publication in the top 10 percentile of the most cited articles. Out of the 15 subject areas listed in SciVal, 7 contribute to more than 65% of publications from Indian institutions. Accordingly, Indian institutions with output in the top 10 percentile greater than the national average in these 7 major subject areas have been identified to compare their research output in terms of quality.

Keywords

Public and Private Institutions, Performance Assessment, Quality and Quantity Perspective, Research Output.

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