Efficient and precise localization is a prerequisite for the intelligent navigation of mobile robots. Traditional visual localization systems, such as visual odometry （VO） and simultaneous localization and mapping ...Efficient and precise localization is a prerequisite for the intelligent navigation of mobile robots. Traditional visual localization systems, such as visual odometry （VO） and simultaneous localization and mapping （SLAM）, suffer from two shortcomings： a drift problem caused by accumulated localization error, and erroneous motion estimation due to illumination variation and moving objects. In this paper, we propose an enhanced VO by introducing a panoramic camera into the traditional stereo-only VO system. Benefiting from the 360° field of view, the panoramic camera is responsible for three tasks： （1） detect- ing road junctions and building a landmark library online; （2） correcting the robot＇s position when the landmarks are revisited with any orientation; （3） working as a panoramic compass when the stereo VO cannot provide reliable positioning results. To use the large-sized panoramic images efficiently, the concept of compressed sensing is introduced into the solution and an adap- tive compressive feature is presented. Combined with our previous two-stage local binocular bundle adjustment （TLBBA） stereo VO, the new system can obtain reliable positioning results in quasi-real time. Experimental results of challenging long-range tests show that our enhanced VO is much more accurate and robust than the traditional VO, thanks to the compressive panoramic landmarks built online.展开更多
Spatial memory of cached food items plays an important role in cache recovery by scatter-hoarding animals.However,whether scatter-hoarding animals intentionally select cache sites with respect to visual landmarks in t...Spatial memory of cached food items plays an important role in cache recovery by scatter-hoarding animals.However,whether scatter-hoarding animals intentionally select cache sites with respect to visual landmarks in the environment and then rely on them to recover their cached seeds for later use has not been extensively explored.Furthermore,there is a lack of evidence on whether there are sex differences in visual landmark-based food-hoarding behaviors in small rodents even though male and female animals exhibit different spatial abilities.In the present study,we used a scatter-hoarding animal,the Siberian chipmunk,Tamias sibiricus to explore these questions in semi-natural enclosures.Our results showed that T.sibiricus preferred to establish caches in the shallow pits labeled with visual landmarks(branches of Pinus sylvestris,leaves of Athyrium brevifrons and PVC tubes).In addition,visual landmarks of P.sylvestris facilitated cache recovery by T.sibiricus.We also found significant sex differences in visual landmark-based food-hoarding strategies in Siberian chipmunks.Males,rather than females,chipmunks tended to establish their caches with respect to the visual landmarks.Our studies show that T.sibiricus rely on visual landmarks to establish and recover their caches,and that sex differences exist in visual landmark-based food hoarding in Siberian chipmunks.展开更多
We describe our research in using environmental visual landmarks as the basis for completing simple robot construction tasks.Inspired by honeybee visual navigation behavior,a visual template mechanism is proposed in w...We describe our research in using environmental visual landmarks as the basis for completing simple robot construction tasks.Inspired by honeybee visual navigation behavior,a visual template mechanism is proposed in which a natural landmark serves as a visual reference or template for distance determination as well as for navigation during collective construction.To validate our proposed mechanism,a wall construction problem is investigated and a minimalist solution is given.Experimental results show that,using the mechanism of a visual template,a collective robotic system can successfully build the desired structure in a decentralized fashion using only local sensing and no direct communication.In addition,a particular variable,which defines tolerance for alignment of the structure,is found to impact the system performance.By decreasing the value of the variable,system performance is improved at the expense of a longer construction time.The visual template mechanism is appealing in that it can use a reference point or salient object in a natural environment that is new or unexplored and it could be adapted to facilitate more complicated building tasks.展开更多
Many scholars have conducted visual analyses of urban skylines, but little attention has been paid to the quantitative measures regarding specific design elements within the skyline. This article aims to help urban de...Many scholars have conducted visual analyses of urban skylines, but little attention has been paid to the quantitative measures regarding specific design elements within the skyline. This article aims to help urban designers and regulators improve the skyline and investigate which factors can make urban skylines more pleasant for people. Computer generated images of skylines are tested for three factors including greenery, layering, and landmarks. For the data collection, a questionnaire was used, as one of the simple and effective methods to gather results. The authors use statistics as a method of measuring the degree of people's preferences. The study finds that the proportions of landmarks in the overall skyline, the height of layers, and the percentage of greenery deserve special attention. The authors also discuss the current problems of skyline design in typical Chinese cities according to the above findings.展开更多
基金Project supported by the National Natural Science Foundation of China （Nos. 61071219 and 90820306） and the Fundamental Research Funds for the Central Universities, China
文摘Efficient and precise localization is a prerequisite for the intelligent navigation of mobile robots. Traditional visual localization systems, such as visual odometry （VO） and simultaneous localization and mapping （SLAM）, suffer from two shortcomings： a drift problem caused by accumulated localization error, and erroneous motion estimation due to illumination variation and moving objects. In this paper, we propose an enhanced VO by introducing a panoramic camera into the traditional stereo-only VO system. Benefiting from the 360° field of view, the panoramic camera is responsible for three tasks： （1） detect- ing road junctions and building a landmark library online; （2） correcting the robot＇s position when the landmarks are revisited with any orientation; （3） working as a panoramic compass when the stereo VO cannot provide reliable positioning results. To use the large-sized panoramic images efficiently, the concept of compressed sensing is introduced into the solution and an adap- tive compressive feature is presented. Combined with our previous two-stage local binocular bundle adjustment （TLBBA） stereo VO, the new system can obtain reliable positioning results in quasi-real time. Experimental results of challenging long-range tests show that our enhanced VO is much more accurate and robust than the traditional VO, thanks to the compressive panoramic landmarks built online.
基金supported by the National Natural Science Foundation(No.31470113 and 31330013)the State Key Laboratory of Integrated Management of Pest Insects and Rodents(ChineseIPM1404)the Program for New Century Excellent Talents in University(NCET-12-0693).
文摘Spatial memory of cached food items plays an important role in cache recovery by scatter-hoarding animals.However,whether scatter-hoarding animals intentionally select cache sites with respect to visual landmarks in the environment and then rely on them to recover their cached seeds for later use has not been extensively explored.Furthermore,there is a lack of evidence on whether there are sex differences in visual landmark-based food-hoarding behaviors in small rodents even though male and female animals exhibit different spatial abilities.In the present study,we used a scatter-hoarding animal,the Siberian chipmunk,Tamias sibiricus to explore these questions in semi-natural enclosures.Our results showed that T.sibiricus preferred to establish caches in the shallow pits labeled with visual landmarks(branches of Pinus sylvestris,leaves of Athyrium brevifrons and PVC tubes).In addition,visual landmarks of P.sylvestris facilitated cache recovery by T.sibiricus.We also found significant sex differences in visual landmark-based food-hoarding strategies in Siberian chipmunks.Males,rather than females,chipmunks tended to establish their caches with respect to the visual landmarks.Our studies show that T.sibiricus rely on visual landmarks to establish and recover their caches,and that sex differences exist in visual landmark-based food hoarding in Siberian chipmunks.
基金Project (No.61075091) supported by the National Natural Science Foundation of China
文摘We describe our research in using environmental visual landmarks as the basis for completing simple robot construction tasks.Inspired by honeybee visual navigation behavior,a visual template mechanism is proposed in which a natural landmark serves as a visual reference or template for distance determination as well as for navigation during collective construction.To validate our proposed mechanism,a wall construction problem is investigated and a minimalist solution is given.Experimental results show that,using the mechanism of a visual template,a collective robotic system can successfully build the desired structure in a decentralized fashion using only local sensing and no direct communication.In addition,a particular variable,which defines tolerance for alignment of the structure,is found to impact the system performance.By decreasing the value of the variable,system performance is improved at the expense of a longer construction time.The visual template mechanism is appealing in that it can use a reference point or salient object in a natural environment that is new or unexplored and it could be adapted to facilitate more complicated building tasks.
基金supported by a soft science research grant (No.2013-R2-43) from the Science and Technology Program funded by the Ministry of Housing and Urban-Rural Development of China
文摘Many scholars have conducted visual analyses of urban skylines, but little attention has been paid to the quantitative measures regarding specific design elements within the skyline. This article aims to help urban designers and regulators improve the skyline and investigate which factors can make urban skylines more pleasant for people. Computer generated images of skylines are tested for three factors including greenery, layering, and landmarks. For the data collection, a questionnaire was used, as one of the simple and effective methods to gather results. The authors use statistics as a method of measuring the degree of people's preferences. The study finds that the proportions of landmarks in the overall skyline, the height of layers, and the percentage of greenery deserve special attention. The authors also discuss the current problems of skyline design in typical Chinese cities according to the above findings.
