Fereshteh Amini

Understanding Data Videos: Looking at Narrative Visualization through the Cinematography Lens

Data videos, motion graphics that incorporate visualizations about facts, are increasingly gaining popularity as a means of telling stories with data. However, very little is systematically recorded about (a) what elements are featured in data videos and (b) the processes used to create them. In this article, we provide initial insights to build this knowledge. We first report on a qualitative analysis of 50 professionally designed data videos, extracting and exposing their most salient constituents. Second, we report on a series of workshops with experienced storytellers from cinematography, graphics design and screenplay writing. We provided them with a set of data facts and visualizations and observed them create storyboards for data videos. From these exploratory studies, we derive broader implications for the design of an authoring tool to enable a wide audience to create data videos. Our findings highlight the importance of providing a flexible tool supporting a non-linear creation process and allowing users to iteratively go back to different phases of the process.

The Impact of Interactivity on Comprehending 2D and 3D Visualizations of Movement Data

GPS, RFID, and other technologies have made it increasingly common to track the positions of people and objects over time as they move through two-dimensional spaces. Visualizing such spatio-temporal movement data is challenging because each person or object involves three variables (two spatial variables as a function of the time variable), and simply plotting the data on a 2D geographic map can result in overplotting and occlusion that hides details. This also makes it difficult to understand correlations between space and time. Software such as GeoTime can display such data with a three-dimensional visualization, where the 3rd dimension is used for time. This allows for the disambiguation of spatially overlapping trajectories, and in theory, should make the data clearer. However, previous experimental comparisons of 2D and 3D visualizations have so far found little advantage in 3D visualizations, possibly due to the increased complexity of navigating and understanding a 3D view. We present a new controlled experimental comparison of 2D and 3D visualizations, involving commonly performed tasks that have not been tested before, and find advantages in 3D visualizations for more complex tasks. In particular, we tease out the effects of various basic interactions and find that the 2D view relies significantly on “scrubbing” the timeline, whereas the 3D view relies mainly on 3D camera navigation. Our work helps to improve understanding of 2D and 3D visualizations of spatio-temporal data, particularly with respect to interactivity.

Performance implications of periodic key exchanges and packet integrity overhead in an 802.15.4 beacon enabled cluster

In this paper, we describe and evaluate a secure data exchange protocol based on the Zigbee specification and built on top of 802.15.4 beacon enabled link layer. This protocol includes a key exchange mechanism and addition of Message Authenication Code to each packet. We have simulated key exchange protocol over physical and data link layers in IEEE 802.15.4 beacon enabled cluster. Since key distribution protocol requires downlink data transmissions which have complex implementation, its communication cost is high. Our results indicate that even for small cluster size, frequent key exchanges impose a serious performance burden on the data traffic. Therefore, the period for key exchanges (i.e. the degree of security protection) has to be traded for the cluster size and throughput.

The Cost of Security: Performance of ZigBee Key Exchange Mechanism in an 802.15.4 Beacon Enabled Cluster

The IEEE 802.15.4 specification is a recent low data rate wireless personal area network standard. While basic security services are provided for, there is a lack of more advanced techniques which are indispensable in modern personal area network applications. In addition, performance implications of those services are not known. In this paper, we describe a secure data exchange protocol based on the ZigBee specification and built on top of 802.15.4 link layer. This protocol includes a key exchange mechanism. Then, we evaluate the overhead of this scheme under different application scenarios. Initial results show the range of network and traffic parameters wherein the proposed scheme is feasible to use

Authoring Data-Driven Videos with DataClips

Data videos, or short data-driven motion graphics, are an increasingly popular medium for storytelling. However, creating data videos is difficult as it involves pulling together a unique combination of skills. We introduce DataClips, an authoring tool aimed at lowering the barriers to crafting data videos. DataClips allows non-experts to assemble data-driven “clips” together to form longer sequences. We constructed the library of data clips by analyzing the composition of over 70 data videos produced by reputable sources such as The New York Times and The Guardian. We demonstrate that DataClips can reproduce over 90% of our data videos corpus. We also report on a qualitative study comparing the authoring process and outcome achieved by (1) non-experts using DataClips, and (2) experts using Adobe Illustrator and After Effects to create data-driven clips. Results indicated that non-experts are able to learn and use DataClips with a short training period. In the span of one hour, they were able to produce more videos than experts using a professional editing tool, and their clips were rated similarly by an independent audience.

Performance of IEEE 802.15.4 Clusters with Power Management and Key Exchange

The IEEE 802.15.4 specification is a recent low data rate wireless personal area network standard. While basic security services are provided for, there is a lack of more advanced techniques which are indispensable in modern personal area network applications. In addition, performance implications of those services are not known. In this paper, we describe a secure data exchange protocol based on the ZigBee specification and built on top of IEEE 802.15.4 link layer. This protocol includes a key exchange mechanism. We assume that all nodes are applying power management technique based on the constant event sensing reliability required by the coordinator. Power management generates random sleep times by every node which in average fairly distributes the sensing load among the nodes. Key exchange is initiated by a cluster coordinator after some given number of sensing packets have been received by the coordinator. We develop and integrate simulation model of the key exchange and power management technique into the cluster’s reliable sensing function. We evaluate the impact of security function and its periodicity on cluster performance.

On Security Attacks in HealthcareWSNs Implemented on 802.15.4 Beacon Enabled Clusters

In this paper, we analyze possible security attacks to the personal WSN carried on the patient’s body and its close vicinity. We assume that WSN is implemented using 802.15.4 beacon enabled technology with a secure sensing, location and power management blocks based on the ZigBee specification and built on top of 802.15.4 link layer. We present networking and security issues which can be used as a basis for security attacks.

Detection of Sybil Attack in Beacon Enabled IEEE802.15.4 Networks

In this paper, we describe a Sybil attack detection algorithm in IEEE 802.15.4 beacon enabled clusters. Our algorithm is based on received signal strength at the cluster coordinator. It considers the multi-path fading and shadowing and uses only two parties to detect the attacks. Using this technique, the detection of sensor displacement attack is also feasible. The results show high accuracy of attack detection and suggest parameter selection values to keep high level of performance. This lightweight scheme suites the IEEE 802.15.4 network nodes which have limitations in terms of battery energy, memory size and CPU speed.

Supporting visual exploration for multiple users in large display environments

We present a design space exploration of interaction techniques for supporting multiple collaborators exploring data on a shared large display. Our proposed solution is based on users controlling individual lenses using both explicit gestures as well as proxemics: the spatial relations between people and physical artifacts such as their distance, orientation, and movement. We discuss different design considerations for implicit and explicit interactions through the lens, and evaluate the user experience to find a balance between the implicit and explicit interaction styles. Our findings indicate that users favor implicit interaction through proxemics for navigation and collaboration, but prefer using explicit mid-air gestures to perform actions that are perceived to be direct, such as terminating a lens composition. Based on these results, we propose a hybrid technique utilizing both proxemics and mid-air gestures, along with examples applying this technique to other datasets. Finally, we performed a usability evaluation of the hybrid technique and observed user performance improvements in the presence of both implicit and explicit interaction styles.

Key Exchange in 802.15.4 Networks and Its Performance Implications

The IEEE 802.15.4 specification is a recent low data rate wireless personal area network standard. While basic security services are provided for, there is a lack of more advanced techniques which are indispensable in modern personal area network applications. In addition, performance implications of those services are not known. In this paper, we describe a secure data exchange protocol based on the Zigbee specification and built on top of 802.15.4 link layer. This protocol includes a key exchange mechanism. Then, we evaluate the overhead of this scheme under different application scenarios. Initial results show the range of network and traffic parameters wherein the proposed scheme is feasible to use.