Measuring the influence of map label density on perceived complexity: a user study using eye tracking

Abstract: We combine eye tracking and a questionnaire-based approach to explore the influence of label density on the perceived visual complexity of maps. We design two experiments in which participants are asked to search for the names of point features on maps and to rate the map complexity and legibility for different label densities. Specifically, we conduct a highly controlled experiment in which all the map variables except the label density are held constant (the controlled experiment). Then, we conduct a second experiment following the same protocol but using real maps as visual stimuli (the real-map experiment) to verify if the results of the controlled experiment were applicable to real maps. The results of both experiments indicate a significantly positive correlation between perceived visual complexity and label density and between the response time in visual search tasks and label density. Surprisingly, we observe a significant inverse correlation between the label density and two eye movement parameters (fixation duration and fixation frequency) between the two experiments. We discuss how the variables of real maps might have affected these eye movement parameters and why the results of the two experiments are inconsistent. Our findings suggest that eye tracking parameters are not reliable indicators of map complexity. These empirical results can be helpful to future map design and map complexity investigation.

Cite this paper:

Liao, H., Wang, X., Dong, W., & Meng, L. (2018). Measuring the influence of map label density on perceived complexity: a user study using eye tracking. Cartography and Geographic Information Science, 1-18. DOI: https://doi.org/10.1080/15230406.2018.1434016

Using Eye Tracking to Explore the Guidance and Constancy of Visual Variables in 3D Visualization

Abstract: An understanding of guidance, which means guiding attention, and constancy, meaning that an area can be perceived for what it is despite environmental changes, of the visual variables related to three-dimensional (3D) symbols is essential to ensure rapid and consistent human perception in 3D visualization. Previous studies have focused on the guidance and constancy of visual variables related to two-dimensional (2D) symbols, but these aspects are not well documented for 3D symbols. In this study, we used eye tracking to analyze the visual guidance from shapes, hues and sizes, and the visual constancy that is related to the shape, color saturation and size of 3D symbols in different locations. Thirty-six subjects (24 females and 12 males) participated in the study. The results indicate that hue and shape provide a high level of visual guidance, whereas guidance from size, a variable that predominantly guides attention in 2D visualization, is much more limited in 3D visualization. Additionally, constancy of shape and saturation are perceived with relatively high accuracy, whereas constancy of size is perceived with only low accuracy. These first empirical studies are intended to pave the way for a more comprehensive user understanding of 3D visualization design.

Cite this paper:

Liu, B.; Dong, W.; Meng, L. Using Eye Tracking to Explore the Guidance and Constancy of Visual Variables in 3D Visualization. ISPRS Int. J. Geo-Inf. 20176, 274. doi: 10.3390/ijgi6090274

董卫华团队参加江苏卫视《最强大脑》节目录制

地理科学学部董卫华老师作为特约嘉宾参加江苏卫视《最强大脑》第四季节目录制,该节目已于2017年1月13日在江苏卫视播出,题目为《一眼辨山》。在节目中,选手通过观察三张随机选取的庐山3D实景图,在庐山全貌等高线地形图中绘制相应的观察点和观察方向,选手答案与正确答案相差在四度以内,点位偏差在两百米以内则回答正确,正确两题则挑战成功。为录制该节目,董卫华老师带队进行了为期半年的研究,并亲赴庐山进行实地考察。以下为该节目的视频:

Selection of LiDAR geometric features with adaptive neighborhood size for urban land cover classification

Abstract: LiDAR has been an effective technology for acquiring urban land cover data in recent decades. Previous studies indicate that geometric features have a strong impact on land cover classification. Here, we analyzed an urban LiDAR dataset to explore the optimal feature subset from 25 geometric features incorporating 25 scales under 6 definitions for urban land cover classification. We performed a feature selection strategy to remove irrelevant or redundant features based on the correlation coefficient between features and classification accuracy of each features. The neighborhood scales were divided into small (0.5–1.5 m), medium (1.5–6 m) and large (>6 m) scale. Combining features with lower correlation coefficient and better classification performance would improve classification accuracy. The feature depicting homogeneity or heterogeneity of points would be calculated at a small scale, and the features to smooth points at a medium scale and the features of height different at large scale. As to the neighborhood definition, cuboid and cylinder were recommended. This study can guide the selection of optimal geometric features with adaptive neighborhood scale for urban land cover classification.

Cite this paper: Dong, W., Lan, J., Liang, S., Yao, W. and Zhan, Z. 2017. Selection of LiDAR geometric features with adaptive neighborhood size for urban land cover classification. International Journal of Applied Earth Observation and Geoinformation, 60, 99-110. DOI: 10.1016/j.jag.2017.04.003

Global and regional changes in exposure to extreme heat and the relative contributions of climate and population change

Abstract: The frequency and intensity of extreme heat wave events have increased in the past several decades and are likely to continue to increase in the future under the influence of human-induced climate change. Exposure refers to people, property, systems, or other elements present in hazard zones that are thereby subject to potential losses. Exposure to extreme heat and changes therein are not just determined by climate changes but also population changes. Here we analyze output for three scenarios of greenhouse gas emissions and socio-economic growth to estimate future exposure change taking account of both climate and population factors. We find that for the higher emission scenario (RCP8.5-SSP3), the global exposure increases nearly 30-fold by 2100. The average exposure for Africa is over 118 times greater than it has been historically, while the exposure for Europe increases by only a factor of four. Importantly, in the absence of climate change, exposure is reduced by 75–95% globally and across all geographic regions, as compared with exposure under the high emission scenario. Under lower emission scenarios RCP4.5-SSP2 and RCP2.6-SSP1, the global exposure is reduced by 65% and 85% respectively, highlighting the efficacy of mitigation efforts in reducing exposure to extreme heat.

继续阅读“Global and regional changes in exposure to extreme heat and the relative contributions of climate and population change”

An Exploratory Study Investigating Gender Effects on Using 3D Maps for Spatial Orientation in Wayfinding

Abstract: 3D representations in applications that provide self-localization and orientation in wayfinding have become increasingly popular in recent years because of technical advances in the field. However, human factors have been largely ignored while designing 3D representations in support of pedestrian navigation. This exploratory study aims to explore gender effects on using 3D maps for spatial orientation. We designed a 3D map that combines salient 3D landmarks and 2D layouts, and evaluated gender differences in their performance during direction-pointing tasks by administrating an eye tracking experiment. The results indicate there was no significant overall gender difference on performance and visual attention. However, we observed that males using the 3D map paid more attention to landmarks in the environment and performed better than when using the conventional 2D map, whereas female performance did not show any significant difference between the two types of map usage. We also observed contrary gender differences in visual attention on landmarks between the 3D and 2D maps. While males fixated longer on landmarks than females when using the 3D map, females paid more visual attention to landmarks than males when using the 2D map. In addition, verbal protocols showed that males had more confidence while make decisions. These empirical results can be helpful in the design of map-based wayfinding enhancement tools.

Cite this paper: Liao H, Dong W. An Exploratory Study Investigating Gender Effects on Using 3D Maps for Spatial Orientation in Wayfinding. ISPRS International Journal of Geo-Information. 2017; 6(3):60. DOI: http://dx.doi.org/10.3390/ijgi6030060

 

Study on the Influence of Field Cognitive Style, Gender and Spatial Terminology on Geographical Spatial Orientation Ability: based on Experiments in Virtual Space

Abstract: Nowadays, studies of factors influencing geographical spatial orientation ability mainly concentrate on gender whereas relationships of field cognitive style and spatial terminology with spatial orientation ability have rarely been studied. This study used eye tracking technology to explore the influences of the three individual variables on spatial orientation ability. 86 people participated in the experiments with an average age of 21 (SD=2.67). 继续阅读“Study on the Influence of Field Cognitive Style, Gender and Spatial Terminology on Geographical Spatial Orientation Ability: based on Experiments in Virtual Space”

Eye tracking to explore the impacts of photorealistic 3d representations in pedestrian navigation performance

Abstract: Despite the now-ubiquitous two-dimensional (2D) maps, photorealistic three-dimensional (3D) representations of cities (e.g., Google Earth) have gained much attention by scientists and public users as another option. However, there is no consistent evidence on the influences of 3D photorealism on pedestrian navigation. Whether 3D photorealism can communicate cartographic information for navigation with higher effectiveness and efficiency and lower cognitive workload compared to the traditional symbolic 2D maps remains unknown. 继续阅读“Eye tracking to explore the impacts of photorealistic 3d representations in pedestrian navigation performance”

Exploring Differences of Visual Attention in Pedestrian Navigation when using 2D Maps and 3D Geo-browsers

Abstract: Despite the now-ubiquitous two-dimensional (2D) electronic maps, three-dimensional (3D) globe viewers, or 3D geo-browsers such as Google Earth and NASA World Wind have gained much attention. However, the effect of such interactive 3D geo-browsers on spatial knowledge acquisition and decision making is not well known. This study aims to explore the potential benefits of using interactive 3D geo-browsers in three processes of pedestrian navigation (self-localization, spatial knowledge acquisition, and decision making) in digital environments. 继续阅读“Exploring Differences of Visual Attention in Pedestrian Navigation when using 2D Maps and 3D Geo-browsers”

The Influence of FOV and Viewing Angle on the Visual Information Processing of 3D Maps

Abstract: Current studies of map symbols mainly concentrate on the basic visual variables such as color, shape and size, which are commonly used in two dimensional maps. Recent technical advances and the ubiquitous use of smart devices have made three- dimensional (3D) maps (e.g., Google Maps and AutoNavi) increasingly popular. However, 3D visual variables, such as field of view (FOV) and viewing angle (VA) which play fundamental roles in visual information processing of 3D maps and spatial scenes, have been rarely investigated. 继续阅读“The Influence of FOV and Viewing Angle on the Visual Information Processing of 3D Maps”