New publication: vegetation response to environmental variables in the mountainous forests of Western Himalaya

New publication: vegetation response to environmental variables in the mountainous forests of Western Himalaya

A recently publisher paper featuring Hooman Latifi and Thorsten Dahms from Dept. of Remote Sensing presents novel results on phenological behaviour of the moist deciduous forests Hymalayan foothills in India during 2013–2015 using Landsat 8 time series data. The paper has been published in International Journal of Remote Sensing, and additionally suggests a new vegetation index called the temporal normalized phenology index (TNPI) to quantify the change in trajectories of Landsat 8 OLIderived normalized difference vegetation index (NDVI) during two time steps of the vegetation growth cycle.

 

Mean NDVI values from April 2014 to June 2015 plotted for study site along with SAL tree
phenology.

 

Based on cross-validated statistics the paper concludes that  TNPI is a superior alternative for the analysis of temporal phenology cycle between two time steps of maximum and minimum vegetation growth periods. This could, in turn, reduce the requirement of large time-series remote-sensing data sets for studies on long-term vegetation phenology. The paper can be retrieved here.

Bibliography:

Khare, S., Ghosh, S.K., Latifi, H., Vijay,S., Dahms,T. 2017. Seasonal-based analysis of vegetation response to environmental variables in the mountainous forests of Western Himalaya using Landsat 8 data. International Journal of Remote Sensing 38(15), 4418-4442.

EAGLE M.Sc. application deadline 2017 is approaching

EAGLE M.Sc. application deadline 2017 is approaching

The EAGLE MSc. application deadline for the upcoming winter term is approaching. Apply within the next 7 days: http://eagle-science.org/apply – all details about needed documents are listed on this page.

Learn within EAGLE how to apply remote sensing for a variety of environmental applications, explore new methods and collaborate with other disciplines. Also read the news by our EAGLE students on their webpage.

More details about the study program or the courses can be found here:

http://eagle-science.org/about/

http://eagle-science.org/courses/

http://eagle-science.org/specialization/

Best practice tutorial on handling low-budget UAV finished

Best practice tutorial on handling low-budget UAV finished

Following the purchase and operaration of our two low-budget UAVs suring 2016 and 2017, a best practice tutorial of how to use the devices was written by Marius Röder, Steven Hill and Hooman Latifi, and it is now available in two English and German versions. This tutorial assumes no prior knowledge of the reader on handling low-budget Unmanned Aerial Vehicles in ecological and environmental contexts. It initially includes general infos on preperation and constellation of a typical UAV system, followed by instructions on planning and implementation of UAV flights using the available commercial software, importing the acquired imagery, relative orientation, optimization of camera parameters, generation of dense point clouds and finally digital surface modeling of the point clouds. The tutorial eventually includes lessons learned, tipps and tricks on further processing and potential applications of the UAV topographic products.
The tutorial can be retrieved here on Research Gate.

New publication: Towards an all-in-one sensor for forestry applications?

New publication: Towards an all-in-one sensor for forestry applications?

A recent paper published by Forestry and featuring Dr. Hooman Latifi from Dept. of Remote Sensing presents novel results of estimating most relevant forest inventory attributes from very high resolution stereoscopic satellite imagery.  The paper couples a systematic review of the state-of-the-art in photogrammetry-basad forest attribute estimation, a case study in southwestern Germany and an expert survey on the potenaitls and pitfalls of remote sensing-assisted forest inventory, in which internationally renowned peers from all over the world took part.

 

Area-based predictions of tree species, aboveground biomass and tree density based on WorldView-2 stereo data

 

The modeling/classification results were comparable to earlier studies in the same test site, obtained with more expensive airborne acquisitions. All in all, the study concludes that the simpler acquisition, reasonable price and the comparably easy data format and handling of VHRSI compared with other sensor types justifies further research on the application of these data for supporting operational forest inventories. The fulltext version of the paper together with the supplementary material can be found here.

Fassnacht, F.E., Mangold, D., Schäfer, J., Immitzer, M., Kattenborn, T., Koch, B and Latifi, H. 2017. Estimating stand density, biomass and tree species from very high resolution stereo-imagery – towards an all-in-one sensor for forestry applications? Forestry, DOI: 10.1093/forestry/cpx014

 

M.Sc. handed in on UAV-based monitoring of post-disturbed forest sites.

M.Sc. handed in on UAV-based monitoring of post-disturbed forest sites.

The M.Sc thesis by Marius Röder (Hochschule für Technik Stuttgart) was handed in. The thesis was supervised by Dr. Hooman Latifi and Prof. Eberhard Gülch and focuses on monitoring post-disturbed and heterogenuous forest sites by cost-effective methods from Unmaned Aerial Vehicle (UAV) domain. The advantage of normalized digital surface models extracted from UAV dta was initially compared to the products derived from standard aerial photography. Subsequently, the suitability of UAV-based inventory was compared to traditional eld methods . For this purpose, reference and UAV data were compared in terms of quality, quantity and cost eectiveness. In addition, an algorithm for automatic tree detection was compared to the manual detection on the UAV-imagery. The extent to which the results differ for certain forest heterogeneity as well as for single and grouped tree individuals was addressed., followed by a cost and benefit analysis of UAV-based forest inventory compared to traditional field-based methods.

 

UAV-based point cloud (left) and UAV-based nDSM (right) of an examplified sample plot in Bavarian Forest National Park

 

the results showed that the UAV inventory can not fully replace the eld methods in terms of quality and quantity due to the general disadvantages of photogrammetric methods in the small-scale forest sites consisting of dense rejuvenation stocks. However, from a purely economic point of view, the advantages over the eld method predominate. Improvements could be achieved by combining field and UAV-methods or a simulteanous use of digital camera and laser scanner mounted on UAV.

UAV and D-GPS fieldwork in the Steigerwald

UAV and D-GPS fieldwork in the Steigerwald

one of our field sites in the Steigerwald

First field work of the year and testing the applicability of our UAV and D-GPS in the Steigerwald at the research station of the University Wuerzburg in Fabrik Schleichach. The research station is part of Prof. Jörg Müllers research department, his staff helped us with the field work and Dr. Simon Thorn, the deputy of the research station gave us a tour of the station and the ongoing research. Several methods to locate ground control points were tested as well as the options to launch the UAV in different types of forest. Additionally, we took images of the research station itself and the plots to evaluate its suitability for later field work and courses. Interesting discussions and potential further collaborations with the biologists working on beetles, bird or fungi composition and distribution, as well as forest composition were also part of it. Tobias Ullmann, Hooman Latifi, Christian Büdel and Martin Wegmann conducted the field work and are now planning further field work in spring and summer as well as joint courses around the research station.

Research Station of the University of Wuerzburg in Steigerwald