Bewegungsanalyse von Videos unter Berücksichtigung von Verdeckungen

Die Aufgabe von Motion Estimation ist, Bewegungsbereiche in einem Video zu erkennen und jedem Bildpunkt eine Bewegung zuzuordnen. Es ist eine herausfordernde Aufgabe von Computer Vision, denn viele Anwendungen des Maschinellen Sehens lassen sich erst durch eine qualitativ hochwertige Bewegungsanalyse des Videos lösen. So sind die hohen Kompressionsraten in Videos mitunter auf die Bewegungskompensation zurückzuführen, welche durch Motion Estimation möglich wird. Eine automatische Erfassung und Identifizierung von Gegenständen oder eine dreidimensionale Szenenrekonstruktion sind Anwendungen, welche eine Bewegungsanalyse voraussetzen. In dieser Arbeit wird ein Algorithmus auf Grundlage der Arbeiten von Jiangjan Xiao und Mubarak Shah entworfen, der eine kurze Videosequenz analysiert. Im Gegensatz zu anderen Arbeiten in diesem Bereich berücksichtigt der Algorithmus Verdeckungen. Das Ergebnis einer Analyse ist eine Ebenenrepräsentation des Videos, bei der jeder Ebene eine affine Bewegung zugrunde liegt. Um die affinen Bewegungen zu finden, sucht der Algorithmus im ersten Schritt Featurepoints. Jeder Featurepoint wird als Saatpunkt im folgenden Region-Growing-Schritt verwendet. In jeder Region-Growing-Wachstumsphase werden die affinen Bewegungen mit dem Newton Näherungsverfahren bis zu einem bestimmten Punkt verfeinert. Ähnliche affine Bewegungen werden zu einer zusammengefasst. Im nächsten Schritt, dem Layer Assignment Schritt, wird eine Energiefunktion entworfen und durch das Minimale-Schnitt-Verfahren minimiert. Durch die Minimierung wird jedem Bildpunkt eine affine Bewegung zugeordnet, was die Lösung des Zuordnungsproblems darstellt. Die Energiefunktion enthält neben Daten- und Smoothnesskosten auch einen Term für Verdeckungen zwischen Bildern und einen Term für Verdeckungen zwischen Bildpaaren. Das Minimale-Schnitt-Verfahren wird seit einigen Jahren häufig für Computer Vision Aufgaben eingesetzt, da es sich in der Praxis gut bewährt.Motion estimation is used to detect motion model parameters and to assign each pixel in a video frame to one of the identified motion models. Motion estimation is a challenging task in computer vision because many applications require high qualitative motion description of the video. For example, the high compression rates of videos are largely depending on the motion compensation of video streams. The automatic identification of objects and the three dimensional scene reconstruction are also depending on motion estimation. In this work, we present an algorithm which is based on the work of Jiangjan Xiao and Mubarak Shah. The algorithm analyses a short video sequence. In contrast to previous work, it takes occlusions into account. The result of the computation is a layered representation of the video, whereby each layer represents one affine motion model. In the first step the algorithm identifies motion parameters. The algorithm selects feature points and uses a region growing method for each feature point. In every growing stage the motion model parameters of the region are re-estimated via the Newton procedure. After this step, similar motions are combined. In the layer assignment step, an energy minimization method is used to minimize a cost function and to assign each pixel to one of the previously identified motion parameters. In addition to common data and smoothness terms, the cost function includes an occlusion term. The energy minimization method is based on graph-cuts

Determining Statistically Robust Changes in Ungulate Browsing Pressure as a Basis for Adaptive Wildlife Management

Ungulate browsing has a major impact on the composition and structure of forests. Repeatedly conducted, large-scale regeneration inventories can monitor the extent of browsing pressure and its impacts on forest regeneration development. Based on the respective results, the necessity and extent of wildlife management activities such as hunting, fencing, etc., can be identified at a landscape scale. However, such inventories have rarely been integrated into wildlife management decision making. In this article, we evaluate a regeneration inventory method which was carried out in the Bavarian Forest National Park between 2007 and 2018. We predict the browsing impact by calculating browsing probabilities using a logistic mixed effect model. To provide wildlife managers with feedback on their activities, we developed a test which can assess significant changes in browsing probability between different inventory periods. To find the minimum observable browsing probability change, we simulated ungulate browsing based on the data of a potential browsing indicator species (Sorbus aucuparia) in the National Park. Sorbus aucuparia is evenly distributed, commonly found, selectively browsed and meets the ecosystem development objectives in our study area. We were able to verify a browsing probability change down to ±5 percentage points with a sample size of about 1,000 observations per inventory run. In view of the size of the National Park and the annual fluctuations in browsing pressure, this estimation accuracy seems sufficient. In seeking the maximal cost-efficiency, we were able to reduce this sample size in a sensitivity analysis by about two thirds without severe loss of information for wildlife management. Based on our findings, the presented inventory method combined with our evaluation tool has the potential to be a robust and efficient instrument to assess the impact of herbivores that are in the National Park and other region.publishedVersio

Biomass functions for the two alien tree species Prunus serotina Ehrh. and Robinia pseudoacacia L. in floodplain forests of Northern Italy

As one cause for biodiversity loss, invasive alien species are a worldwide threat. In forests, however, invasive tree species can also have an enormous biomass potential which can be harvested while taking measures against the species. Allometric equations help estimating the biomass but are often only available for the native range of the species. This lack on information complicates the management of invaded stands, and the equations presented here should help fill this gap. The above-ground biomass for single trees of black cherry (Prunus serotina Ehrh.) and black locust (Robinia pseudoacacia L.) in Ticino/Italy was estimated with differing explanatory variables as total, stem, crown, and leaf biomass. Regression equations of P. serotina were compared with equations from North America. The methods to derive biomass estimates from fresh weight and volumetric measurements in combination with wood densities were critically examined. The biomass could be estimated well by using "diameter" as explanatory variable. The productivity of P. serotina was lower here compared to its range of origin. Biomass estimates from volumetric measurements combined with the truncated cone formula have lead to systematic overestimations. Also the use of volumetric measurements combined with wood density measurements has overestimated comparable estimates from fresh weight measurements. peerReviewe

Bioenergie-Regionen stärken

Die Produktion und Bereitstellung holzbasierter Biomasse zur Energiegewinnung ist ein Baustein der Energiewende. Dabei spielen so unterschiedliche Herausforderungen wie Flächenverfügbarkeit, ökonomische Konkurrenzfähigkeit gegenüber anderen Landnutzungsformen bis hin zur öko logischen Verträglichkeit von Energieholz eine Rolle

Advanced Aboveground Spatial Analysis as Proxy for the Competitive Environment Affecting Sapling Development

Tree saplings are exposed to a competitive growth environment in which resources are limited and the ability to adapt determines general vitality and specific growth performance. In this study we analyzed the aboveground spatial neighborhood of oak [Quercus petraea (Matt.) Liebl.] and beech (Fagus sylvatica L.) saplings growing in Germany, by using hemispherical photography and terrestrial laser scanning as proxy for the competitive pressure saplings were exposed to. The hemispherical images were used to analyze the light availability and the three-dimensional (3D) point clouds from the laser scanning were used to assess the space and forest structure around the saplings. The aim was to increase the precision with which the biomass allocation, growth, and morphology of the saplings could be predicted by including more detailed information of their environment. The predictive strength of the models was especially increased through direct neighborhood variables (e.g., relative space filling), next to the light availability being the most important predictor variable. The biomass allocation patterns within the more light demanding oak were strongly driven by the space availability around the saplings. Diameter and height growth variables of both species reacted significantly to changes in light availability, and partly also to the neighborhood variables. The leaf morphology [as leaf-area ratio (LAR)] was also driven by light availability and decreased with increasing light availability. However, the branch morphology (as mean branch weight) could not be explained for oak and the model outcome for beech was hard to interpret. The results could show that individuals of the same species perform differently under constant light conditions but differing neighborhoods. Assessing the neighborhood of trees with highly precise measurement devices, like terrestrial laser scanners, proved to be useful. However, the primary response to a dense neighborhood seemed to be coping with a reduction of the lateral light availability aboveground, rather than responding to an increase of competition belowground. The results suggest continuing efforts to increase the precision with which plant environments can be described through innovative and efficient methods, like terrestrial laser scanning

Bedarfsgerechte Riboflavin-(Vitamin B2-)Versorgung bei langsam wachsenden Masthühnern

In zwei Durchgängen mit jeweils 800 gemischtgeschlechtlichen Eintagsküken der Genetik Ranger Gold™ wurde ein auf Basis der Fermentation des Hefe-Pilzes Ashbya gossypii hergestelltes Trockenprodukt untersucht. Es wurden vier unterschiedliche Riboflavingehalte je Durchgang getestet. Eine Kontrollmischung enthielt ausschließlich native Riboflavingehalte ohne Zudosierung. In den ersten zwei Wochen erhielten die Tiere Starterfutter, in den folgenden vier Wochen Aufzuchtfutter 1 und in den letzten zwei Wochen Aufzuchtfutter 2. Wöchentlich wurden Tiergewicht und Futterverbrauch erfasst. Bei der Schlachtung wurden Schlachtparameter erhoben. Die nativen Riboflavingehalte konnten den Bedarf der langsam wachsenden Masthühner nicht decken. Hohe Zudosierungen hingegen zeigten keinen positiven Effekt auf die Leistungs- und Schlachtparameter. Eine Reduktion der Riboflavin-Supplementierung insbesondere in den späteren Mastabschnitten scheint daher geeignet, die erhöhten Kosten, die beim Einsatz des getesteten Produktes im Vergleich zu günstigeren Produkten, welche mit gentechnisch veränderten Mikroorganismen hergestellt werden, auszugleichen

Relationship between tree growth and physical dimensions of Fagus sylvatica crowns assessed from terrestrial laser scanning

Measurements of physical tree crown dimensions were of subjective character in the past, even though they can be considered important for the management of many silvicultural operations, such as timing of thinning operations. In our study we investigated if and how measures of physical crown dimensions of trees differed when quantified conventionally versus based on 3D-terrestrial laser scanning and how they are related to basal area increment. Some 24 randomly selected predominant or dominant beech trees between 90 and 110 yrs of age and of varying height were used as study trees. We hypothesized that tree crown dimensions obtained from scans are more closely related to tree radial growth than those obtained from conventional field measurements. It was found that from a variety of compared crown size characteristics the scan-based tree attributes mean crown radius, maximum area of the crown and crown projection area were most closely related to individual tree growth. We conclude that the horizontal extension of a tree crown in general is to be considered one of the most important drivers of tree growth. We also conclude that terrestrial laser scanning is a powerful tool to reliably measure physical crown dimensions and TLS-based measurements are more reliable than conventional onesThis is the publisher’s final pdf. The published article is copyrighted by the Italian Society of Silviculture and Forest Ecology and can be found at: http://www.sisef.it/iforest/Keywords: Crown Surface Area, Tree Geometry, Crown Structure, Basal Area Incremen

Forest Structure and Fine Root Biomass Influence Soil CO 2 Efflux in Temperate Forests under Drought

Soil respiration is rarely studied at the landscape scale where forest and soil properties can be important drivers. We performed forest and soil inventories in 150 temperate forest sites in three German landscapes and measured in situ soil CO 2 efflux with the soda-lime method in early summer 2018 and 2019. Both years were affected by naturally occurring summer droughts. Our aim was to investigate the impact of forest structural and compositional properties, soil properties and climate on soil CO 2 efflux at the landscape. Forest properties explained a large portion of soil CO 2 efflux variance (i.e., 14% in 2018 and 20% in 2019), which was comparable or larger than the portion explained by soil properties (i.e., 15% in 2018 and 6% in 2019), and much larger than that of climate. Using Structural Equation Modeling, we found that forest structural properties, i.e., tree density and basal area, were negatively linked to soil CO 2 efflux, while forest composition, i.e., conifer share and tree species richness, was not important. Forest structure effects on soil CO 2 efflux were either direct or mediated by fine root biomass under dry summer conditions. Summer soil CO 2 efflux was positively linked to fine root biomass but not related to total soil organic carbon stocks or climate. Forest structural properties influence soil CO 2 efflux under drought events and should be considered when predicting soil respiration at the landscape scale

It is not just a ‘trade‐off’: : indications for sink‐ and source‐limitation to vegetative and regenerative growth in an old‐growth beech forest

Summary Controls on tree growth are key issues in plant physiology. The hypothesis of our study was that the interannual variability of wood and fruit production are primarily controlled directly by weather conditions (sink limitation), while carbon assimilation (source limitation) plays a secondary role. We analyzed the interannual variability of weather conditions, gross primary productivity (GPP) and net primary productivity (NPP) of wood and fruits of an old‐growth, unmanaged Fagus sylvatica forest over 14 yr, including six mast years. In a multiple linear regression model, c . 71% of the annual variation in wood‐NPP could be explained by mean air temperature in May, precipitation from April to May (positive influence) and fruit‐NPP (negative influence). GPP of June to July solely explained c . 42% of the variation in wood‐NPP. Fruit‐NPP was positively related to summer precipitation 2 yr before ( R 2 = 0.85), and negatively to precipitation in May ( R 2 = 0.83) in the fruit years. GPP had no influence on fruit‐NPP. Our results suggest a complex system of sink and source limitations to tree growth driven by weather conditions and going beyond a simple carbon‐mediated ‘trade‐off’ between regenerative and vegetative growth