Improvement of registration accuracy of a handheld augmented reality system for urban landscape simulation

The need for visual landscape assessment in large-scale projects for the evaluation of the effects of a particular project on the surrounding landscape has grown in recent years. Augmented reality （AR） has been considered for use as a landscape simulation system in which a landscape assessment object created by 3D models is included in the present surroundings. With the use of this system, the time and the cost needed to perform a 3DCG modeling of present surroundings, which is a major issue in virtual reality, are drastically reduced. This research presents the development of a 3D maporiented handheld AR system that achieves geometric consistency using a 3D map to obtain position data instead of GPS, which has tow position information accuracy, particularly in urban areas. The new system also features a gyroscope sensor to obtain posture data and a video camera to capture live video of the present surroundings. All these components are mounted in a smartphone and can be used for urban landscape assessment. Registration accuracy is evaluated to simulate an urban landscape from a short- to a long-range scale. The latter involves a distance of approximately 2000 m. The developed AR system enables users to simulate a Landscape from multiple and longdistance viewpoints simultaneously and to walk around the viewpoint fields using only a smartphone. This result is the tolerance level of Landscape assessment. In conclusion, the proposed method is evaluated as feasible and effective.

Estimating landscape structure efects on pollination for management of agricultural landscapes

Background:The growing human population around the world is creating an increased demand for food.In agricultural landscapes,forests are cleared and turned into agricultural land to produce more food.Increasing the productivity of agricultural land per unit area may prevent extreme forest degradation.Since many agricultural products are dependent on pollinators,it is possible to increase crop production by increasing the pollination rate in the agricultural landscapes.Pollinators are highly dependent on forest patches in agricultural landscapes.Therefore,by creating new forest patches around agricultural felds,we can increase the pollination rate,and thus the crop production.In this regard,estimating the efects of diferent scenarios of forest fragmentation helps us to fnd an optimized pattern of forest patches for increasing pollination in an agricultural landscape.Methods:To investigate the efect of diferent forest fragmentation scenarios on pollination,we used simulated agricultural landscapes,including diferent forest proportions and degrees of fragmentation.Using landscape metrics,we estimated the relationship between pollination and landscape structure for each landscape.Results:Our results showed that for increasing pollination,two signifcant factors should be considered:habitat amount and capacity of small patches to supply pollination.We found that when the capacity of small patches in supplying pollination was low,fragmented patterns of forest patches decreased pollination.With increasing capacity,landscapes with a high degree of forest fragmentation showed the highest levels of pollination.There was an exception for habitat amounts(the proportion of forest patches)less than 0.1 of the entire landscape where increasing edge density,aggregation,and the number of forest patches resulted in increasing pollination in all scenarios.Conclusion:This study encourages agriculturists and landscape planners to focus on increasing crop production per unit area by pollinators because it leads to biodiversity conservation and reduces socio-economic costs of land-use changes.We also suggest that to increase pollination in agricultural landscapes by creating new forest patches,special attention should be paid to the capacity of patches in supporting pollinators.

Plant-pollinator metanetworks in fragmented landscapes:a simulation study

Background The topology of the plant-pollinator network can be explained by the species’abundance and their random interactions.Plant-pollinator networks can be studied in the context of a landscape,because each patch can accommodate a certain local network.Local populations of pollinators in the landscape can be connected through migration and then constitute a metanetwork that is known as a combination of spatial and ecological networks.In this regard,habitat fragmentation can affect the topology of plant-pollinator metanetworks through changes in the species abundance and limiting their interactions.However,it is not clear what pattern(fragmented or aggregated)of the landscape structure can accommodate networks with a higher degree of specialization.Methods we created simulated landscapes with different forest proportions scenarios(from 5%to 50%of the total landscape)and degrees of fragmentation.Then,for each landscape,we limited the proportion of pollinators to the forest patch.We assumed that plants and pollinators are randomly distributed around the landscape and interact randomly.We used landscape metrics to measure different aspects of landscape structure and bipartite metrics for calculating the degree of specialization in plant-pollinator networks.Results The statistical relationship between bipartite and landscape metrics showed that the relationship between the topology of plant-pollinator networks and the landscape structure is affected by the forest amount in the landscape and the degree of forest fragmentation.We also found that according to the nestedness and H2(a measure of specialization)metrics,fragmented landscapes contain more general plant-pollinator networks.Conclusions Our findings suggest that fragmented landscapes,characterized by scattered forest patches,can promote higher levels of interaction between limited pollinators and diverse flowers,leading to more general plant-pollinator networks.