We present results from a user study that compared six visualization methods for 2D vector data. ... more We present results from a user study that compared six visualization methods for 2D vector data. Two methods used different distributions of short arrows, two used different distributions of integral curves, one used wedges located to suggest flow lines, and the final was line-integral convolution (LIC). We defined three simple but representative tasks for users to perform using visualizations from each method: 1) locating all critical points in an image, 2) identifying critical point types, and 3) advecting a particle.
IEEE Transactions on Visualization and Computer Graphics, 2005
We present results from a user study that compared six visualization methods for two-dimensional ... more We present results from a user study that compared six visualization methods for two-dimensional vector data. Users performed three simple but representative tasks using visualizations from each method: 1) locating all critical points in an image, 2) identifying critical point types, and 3) advecting a particle. Visualization methods included two that used different spatial distributions of short arrow icons, two that used different distributions of integral curves, one that used wedges located to suggest flow lines, and line-integral convolution (LIC). Results show different strengths and weaknesses for each method. We found that users performed these tasks better with methods that: 1) showed the sign of vectors within the vector field, 2) visually represented integral curves, and 3) visually represented the locations of critical points. Expert user performance was not statistically different from nonexpert user performance. We used several methods to analyze the data including omnibus analysis of variance, pairwise t-tests, and graphical analysis using inferential confidence intervals. We concluded that using the inferential confidence intervals for displaying the overall pattern of results for each task measure and for performing subsequent pairwise comparisons of the condition means was the best method for analyzing the data in this study. These results provide quantitative support for some of the anecdotal evidence concerning visualization methods. The tasks and testing framework also provide a basis for comparing other visualization methods, for creating more effective methods and for defining additional tasks to further understand the tradeoffs among the methods. In the future, we also envision extending this work to more ambitious comparisons, such as evaluating two-dimensional vectors on two-dimensional surfaces embedded in three-dimensional space and defining analogous tasks for three-dimensional visualization methods.
To review our experience and examine the size at which aneurysms ruptured in our patient populati... more To review our experience and examine the size at which aneurysms ruptured in our patient population. Patient charts and angiograms for all patients admitted with a diagnosis of subarachnoid hemorrhage to the Thomas Jefferson/Wills Eye Hospital between April 1996 and March 2000 were reviewed. Of the 362 cases reviewed, definite measurements of the ruptured aneurysm were obtained in 245. The data clearly showed that most ruptured aneurysms presenting to our institution were less than 10 mm in diameter. We found that, regardless of location on the circle of Willis, 85.6% of all aneurysms presenting with rupture were less than 10 mm. Review by location shows that aneurysms of the anterior communicating artery most often presented with rupture at sizes less than 10 mm (94.4%). A large number of ruptured posterior communicating artery aneurysms also presented at sizes less than 10 mm (87.5%). This trend continued for all aneurysm sites in our review. The incidence of subarachnoid hemorrhage in Western countries is estimated at 10 per 100,000 people per year. Recent reports have indicated that aneurysms less than 10 mm in size are unlikely to rupture. We argue that the risk of small aneurysms rupturing is not insignificant, especially those of the anterior communicating artery. Our findings indicate that surgery on unruptured aneurysms should not be predicated on aneurysm size alone.
Pancreas graft loss due to venous thrombosis is the leading non-immunological cause for graft fai... more Pancreas graft loss due to venous thrombosis is the leading non-immunological cause for graft failure following kidney-pancreas transplantation. Thromboelastography (TEG)-directed anticoagulation protocol has shown that approximately one-third of the patients undergoing pancreas transplantation require therapeutic anticoagulation to prevent the occurrence of graft thrombosis. This article presents the argument for individualised anticoagulation in these patients based on their TEG tracings and suggests the use of TEG in patients undergoing pancreas transplantation.
We present results from a user study that compared six visualization methods for 2D vector data. ... more We present results from a user study that compared six visualization methods for 2D vector data. Two methods used different distributions of short arrows, two used different distributions of integral curves, one used wedges located to suggest flow lines, and the final was line-integral convolution (LIC). We defined three simple but representative tasks for users to perform using visualizations from each method: 1) locating all critical points in an image, 2) identifying critical point types, and 3) advecting a particle.
IEEE Transactions on Visualization and Computer Graphics, 2005
We present results from a user study that compared six visualization methods for two-dimensional ... more We present results from a user study that compared six visualization methods for two-dimensional vector data. Users performed three simple but representative tasks using visualizations from each method: 1) locating all critical points in an image, 2) identifying critical point types, and 3) advecting a particle. Visualization methods included two that used different spatial distributions of short arrow icons, two that used different distributions of integral curves, one that used wedges located to suggest flow lines, and line-integral convolution (LIC). Results show different strengths and weaknesses for each method. We found that users performed these tasks better with methods that: 1) showed the sign of vectors within the vector field, 2) visually represented integral curves, and 3) visually represented the locations of critical points. Expert user performance was not statistically different from nonexpert user performance. We used several methods to analyze the data including omnibus analysis of variance, pairwise t-tests, and graphical analysis using inferential confidence intervals. We concluded that using the inferential confidence intervals for displaying the overall pattern of results for each task measure and for performing subsequent pairwise comparisons of the condition means was the best method for analyzing the data in this study. These results provide quantitative support for some of the anecdotal evidence concerning visualization methods. The tasks and testing framework also provide a basis for comparing other visualization methods, for creating more effective methods and for defining additional tasks to further understand the tradeoffs among the methods. In the future, we also envision extending this work to more ambitious comparisons, such as evaluating two-dimensional vectors on two-dimensional surfaces embedded in three-dimensional space and defining analogous tasks for three-dimensional visualization methods.
To review our experience and examine the size at which aneurysms ruptured in our patient populati... more To review our experience and examine the size at which aneurysms ruptured in our patient population. Patient charts and angiograms for all patients admitted with a diagnosis of subarachnoid hemorrhage to the Thomas Jefferson/Wills Eye Hospital between April 1996 and March 2000 were reviewed. Of the 362 cases reviewed, definite measurements of the ruptured aneurysm were obtained in 245. The data clearly showed that most ruptured aneurysms presenting to our institution were less than 10 mm in diameter. We found that, regardless of location on the circle of Willis, 85.6% of all aneurysms presenting with rupture were less than 10 mm. Review by location shows that aneurysms of the anterior communicating artery most often presented with rupture at sizes less than 10 mm (94.4%). A large number of ruptured posterior communicating artery aneurysms also presented at sizes less than 10 mm (87.5%). This trend continued for all aneurysm sites in our review. The incidence of subarachnoid hemorrhage in Western countries is estimated at 10 per 100,000 people per year. Recent reports have indicated that aneurysms less than 10 mm in size are unlikely to rupture. We argue that the risk of small aneurysms rupturing is not insignificant, especially those of the anterior communicating artery. Our findings indicate that surgery on unruptured aneurysms should not be predicated on aneurysm size alone.
Pancreas graft loss due to venous thrombosis is the leading non-immunological cause for graft fai... more Pancreas graft loss due to venous thrombosis is the leading non-immunological cause for graft failure following kidney-pancreas transplantation. Thromboelastography (TEG)-directed anticoagulation protocol has shown that approximately one-third of the patients undergoing pancreas transplantation require therapeutic anticoagulation to prevent the occurrence of graft thrombosis. This article presents the argument for individualised anticoagulation in these patients based on their TEG tracings and suggests the use of TEG in patients undergoing pancreas transplantation.
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