scholarly journals On the spatial extent of attention in object-based visual selection

1996 ◽  
Vol 58 (8) ◽  
pp. 1238-1251 ◽  
Author(s):  
Nilli Lavie ◽  
Jon Driver
Author(s):  
Niels Svane ◽  
Troels Lange ◽  
Sara Egemose ◽  
Oliver Dalby ◽  
Aris Thomasberger ◽  
...  

Traditional monitoring (e.g., in-water based surveys) of eelgrass meadows and perennial macroalgae in coastal areas is time and labor intensive, requires extensive equipment, and the collected data has a low temporal resolution. Further, divers and Remotely Operated Vehicles (ROVs) have a low spatial extent that cover small fractions of full systems. The inherent heterogeneity of eelgrass meadows and macroalgae assemblages in these coastal systems makes interpolation and extrapolation of observations complicated and, as such, methods to collect data on larger spatial scales whilst retaining high spatial resolution is required to guide management. Recently, the utilization of Unoccupied Aerial Vehicles (UAVs) has gained popularity in ecological sciences due to their ability to rapidly collect large amounts of area-based and georeferenced data, making it possible to monitor the spatial extent and status of SAV communities with limited equipment requirements compared to ROVs or diver surveys. This paper is focused on the increased value provided by UAV-based, data collection (visual/Red Green Blue imagery) and Object Based Image Analysis for gaining an improved understanding of eelgrass recovery. It is demonstrated that delineation and classification of two species of SAV ( Fucus vesiculosus and Zostera marina) is possible; with an error matrix indicating 86–92% accuracy. Classified maps also highlighted the increasing biomass and areal coverage of F. vesiculosus as a potential stressor to eelgrass meadows. Further, authors derive a statistically significant conversion of percentage cover to biomass ( R2 = 0.96 for Fucus vesiculosus, R2 = 0.89 for Zostera marina total biomass, and R2 = 0.94 for AGB alone, p < 0.001). Results here provide an example of mapping cover and biomass of SAV and provide a tool to undertake spatio-temporal analyses to enhance the understanding of eelgrass ecosystem dynamics.


2016 ◽  
Vol 180 ◽  
pp. 35-54
Author(s):  
Alcides X. Benicasa ◽  
Marcos G. Quiles ◽  
Thiago C. Silva ◽  
Liang Zhao ◽  
Roseli A.F. Romero

Author(s):  
Alcides X. Benicasa ◽  
Marcos G. Quiles ◽  
Liang Zhao ◽  
Roseli A.F. Romero

2019 ◽  
Vol 73 (1) ◽  
pp. 29-54 ◽  
Author(s):  
Christoph von Castell ◽  
Heiko Hecht ◽  
Daniel Oberfeld

The texture of an object’s surface influences its perceived spatial extent. For example, Hermann von Helmholtz reported that a square patch with black and white stripes appears elongated perpendicular to the stripes’ orientation. This time-honoured finding stands in contrast with more recent recommendations by interior-design experts who suggest that stripe wall patterns make rooms appear elongated in the direction parallel to the stripes’ orientation. In a series of four experiments, we presented stripe wall patterns and varied the orientation of the stripes (horizontal vs. vertical) and their density (number of stripes per degree of visual angle). Subjects estimated the width and height of stereoscopically presented interior spaces. Stripe patterns with higher densities made rooms appear both wider and higher than did stripe patterns with lower densities or plain walls. In contrast to both the predictions from the Helmholtz-square and the design guidelines, this effect was only weakly modulated by pattern orientation, in the sense that rooms appeared elongated in the direction parallel to the stripes’ orientation. We conclude that object-based texture effects cannot be generalised to interior space perception. For a room’s perceived spatial extent, pattern density is more important than pattern orientation.


Author(s):  
Alcides X. Benicasa ◽  
Marcos G. Quiles ◽  
Thiago C. Silva ◽  
Liang Zhao ◽  
Roseli A.F. Romero

1998 ◽  
Vol 9 (2) ◽  
pp. 104-110 ◽  
Author(s):  
Cathleen M. Moore ◽  
Steven Yantis ◽  
Barry Vaughan

A large body of evidence suggests that visual attention selects objects as well as spatial locations. If attention is to be regarded as truly object based, then it should operate not only on object representations that are explicit in the image, but also on representations that are the result of earlier perceptual completion processes. Reporting the results of two experiments, we show that when attention is directed to part of a perceptual object, other parts of that object enjoy an attentional advantage as well. In particular, we show that this object-specific attentional advantage accrues to partly occluded objects and to objects defined by subjective contours. The results corroborate the claim that perceptual completion precedes object-based attentional selection.


Author(s):  
Catherine M. Arrington ◽  
Dale Dagenbach ◽  
Maura K. McCartan ◽  
Thomas H. Carr
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document