Dunphy, P. and Yan, J. 2007. Do background images improve "draw a secret" graphical passwords?. In Proceedings of the 14th ACM Conference on Computer and Communications Security (Alexandria, Virginia, USA, October 28 - 31, 2007). CCS '07. ACM, New York, NY, 36-47.
Summary
The authors use DAS passwords in conjunction with background images in order to improve the complexity of the passwords without harming user recall. A user would typically choose a small portion of an image to draw on, which could increase the complexity of the password if the image itself was complex.
The paper contains great user studies focusing on the recall of passwords, the complexity of images, what images users chose to draw on, and what recall errors occurred.
Discussion
This is another DAS paper, and, like the previously blogged one, shows how much room the graphical password field has to grow. The studies in this paper were phenomenally thorough, and if we ever start a sketching passwords project this is the paper we should all read.
Sunday, February 22, 2009
Graphical Passwords & Qualitative Spatial Relations
Lin, D., Dunphy, P., Olivier, P., and Yan, J. 2007. Graphical passwords & qualitative spatial relations. In Proceedings of the 3rd Symposium on Usable Privacy and Security (Pittsburgh, Pennsylvania, July 18 - 20, 2007). SOUPS '07, vol. 229. ACM, New York, NY, 161-162.
Summary
The authors modify the Draw-a-Secret (DAS) scheme where users draw a graphical password in a grid so that the "looking over the shoulder" phenomenon could be reduced. A DAS password is a simple encoding of a drawn stroke using a grid and directions, such as up, right, up.
The extended abstract presents a Qualitative Draw-a-Secret (QDAS) scheme that changes DAS by first assigning a number to each grid. Then, the grid itself varies based on the direction changes of the stroke. The grid changes based on cell height and width.
Discussion
Although this extended abstract wasn't too informative, it did give me some thoughts about how we could use sketch recognition techniques to improve upon drawn passwords.
Summary
The authors modify the Draw-a-Secret (DAS) scheme where users draw a graphical password in a grid so that the "looking over the shoulder" phenomenon could be reduced. A DAS password is a simple encoding of a drawn stroke using a grid and directions, such as up, right, up.
The extended abstract presents a Qualitative Draw-a-Secret (QDAS) scheme that changes DAS by first assigning a number to each grid. Then, the grid itself varies based on the direction changes of the stroke. The grid changes based on cell height and width.
Discussion
Although this extended abstract wasn't too informative, it did give me some thoughts about how we could use sketch recognition techniques to improve upon drawn passwords.
Monday, February 16, 2009
SKIT: A Computer-Assisted Sketch Instruction Tool
Greg Coombe and Brian Salomon
Department of Computer Science, University of North Carolina
This paper discusses a system, SKIT, that assists users in sketching line drawings by using some artist techniques. The system breaks a full outline sketch into subdrawings that the user can draw at various sizes. This allows the user to see the model they are drawing as a set of smaller, more geometric objects. The subdrawings are then merged back together in the end.
The small user study was more qualitative and showed users improved when using SKIT.
Discussion:
The paper presents a technique or two that might be helpful in starting a user-training program for sketching.
Department of Computer Science, University of North Carolina
This paper discusses a system, SKIT, that assists users in sketching line drawings by using some artist techniques. The system breaks a full outline sketch into subdrawings that the user can draw at various sizes. This allows the user to see the model they are drawing as a set of smaller, more geometric objects. The subdrawings are then merged back together in the end.
The small user study was more qualitative and showed users improved when using SKIT.
Discussion:
The paper presents a technique or two that might be helpful in starting a user-training program for sketching.
Monday, April 28, 2008
Invariant features for 3-D gesture recognition
Summary:
Campbell et al. use HMMs and a list of features to find a good recognition rate for a set of T'ai Chi gestures that are performed by users in a swivel chair; a hand gesture's change in polar coordinates provided the highest recognition for the 18 gestures tested.
Discussion:
Performing T'ai Chi in a chair kind of defeats the purpose of T'ai Chi. That's like trying to study race car drivers by observing people who take the bus.
Campbell et al. use HMMs and a list of features to find a good recognition rate for a set of T'ai Chi gestures that are performed by users in a swivel chair; a hand gesture's change in polar coordinates provided the highest recognition for the 18 gestures tested.
Discussion:
Performing T'ai Chi in a chair kind of defeats the purpose of T'ai Chi. That's like trying to study race car drivers by observing people who take the bus.
Wednesday, April 23, 2008
FreeDrawer - A Free-Form Sketching System on the Responsive Workbench
Summary:
Wesche et al. created a 3D sketching tool where the skeleton of a model is created. A user can draw curves in a virtual space. A new curve can be drawn anywhere, but additional curves must be merged with the present model. Altering curves can be done on a local or global scale. Surfaces can be filled in at closed curve loops. Surfaces can also be smoothed.
Discussion:
This paper had some nice pictures, but very little material was actually presented. How does the computer know where the pen point is? How does the user interact with the pen? Range of motion? Gestures?
Wesche et al. created a 3D sketching tool where the skeleton of a model is created. A user can draw curves in a virtual space. A new curve can be drawn anywhere, but additional curves must be merged with the present model. Altering curves can be done on a local or global scale. Surfaces can be filled in at closed curve loops. Surfaces can also be smoothed.
Discussion:
This paper had some nice pictures, but very little material was actually presented. How does the computer know where the pen point is? How does the user interact with the pen? Range of motion? Gestures?
Interacting with human physiology
Summary:
The authors Pavlidis et al. propose a system to monitor humans for stress levels and altered psychological states using high-end infrared cameras. This system could then be used for a variety of purposes such as stress management of UIs, illness detection, or lie detection.
The system tracks the user's face through tandem tracking to track a small, keys section of the face. These sections include the nose, forehead, and temporal regions. The tracker models each region by its center of mass and orientation. Blood flow is tracked in the face through a perfusion model and directional model. The model involves a differential equation set to measure the "volumetric metabolic heat" flow in the face. Other measurements tracked include pulse, heat transfer in areas, and breathing rate.
Discussion:
The ideas behind this system are great, although talking with Pavlidis showed us that there are issues with the current system's usability. Sweat and minor body temperature fluctuations can alter the system's reliability (since the system is trying to measure minor fluctuations). Unfortunately, the cost for one of these high-end cameras is $60k, so we won't be seeing this any time soon.
The authors Pavlidis et al. propose a system to monitor humans for stress levels and altered psychological states using high-end infrared cameras. This system could then be used for a variety of purposes such as stress management of UIs, illness detection, or lie detection.
The system tracks the user's face through tandem tracking to track a small, keys section of the face. These sections include the nose, forehead, and temporal regions. The tracker models each region by its center of mass and orientation. Blood flow is tracked in the face through a perfusion model and directional model. The model involves a differential equation set to measure the "volumetric metabolic heat" flow in the face. Other measurements tracked include pulse, heat transfer in areas, and breathing rate.
Discussion:
The ideas behind this system are great, although talking with Pavlidis showed us that there are issues with the current system's usability. Sweat and minor body temperature fluctuations can alter the system's reliability (since the system is trying to measure minor fluctuations). Unfortunately, the cost for one of these high-end cameras is $60k, so we won't be seeing this any time soon.
3D Object Modeling Using Spatial and Pictographic Gestures
Summary:
Nishino et al. designed a 3D object modeling system that uses stereoscopic glasses, CyberGloves, and polhemus trackers.
The system allows the creation of superellipsoids that can have smooth or squarish parameters. These primitive shapes can be bent, stretched, twisted, and merged with other shapes. Hand postures control these actions, such as grasping and pointing. Virtual hands are displayed on a 200-inch arched screen, along with the object, in stereoscopic mode. The virtual hands allow the user to easily see where they can touch and modify the 3D model.
The authors tested the system by having users attempt two types of objects: symmetric and asymmetric. The symmetric object was a bottle, and the asymmetric object was a teapot.
Creation of the objects took up to 120 minutes. The size of the stored objects was much less than a competing program, Open Inventor.
Discussion:
For a paper in 1998, this was a pretty advanced system and seemed to offer some benefits over other systems. I would have liked to have seen feedback from the users, though, since I'm not sure how hard the system is to use.
Nishino et al. designed a 3D object modeling system that uses stereoscopic glasses, CyberGloves, and polhemus trackers.
The system allows the creation of superellipsoids that can have smooth or squarish parameters. These primitive shapes can be bent, stretched, twisted, and merged with other shapes. Hand postures control these actions, such as grasping and pointing. Virtual hands are displayed on a 200-inch arched screen, along with the object, in stereoscopic mode. The virtual hands allow the user to easily see where they can touch and modify the 3D model.
The authors tested the system by having users attempt two types of objects: symmetric and asymmetric. The symmetric object was a bottle, and the asymmetric object was a teapot.
Creation of the objects took up to 120 minutes. The size of the stored objects was much less than a competing program, Open Inventor.
Discussion:
For a paper in 1998, this was a pretty advanced system and seemed to offer some benefits over other systems. I would have liked to have seen feedback from the users, though, since I'm not sure how hard the system is to use.
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