Ms. Haleh H. Hagh-Shenas Profile

Haleh H. Hagh-Shenas

at Univ of Minnesota

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 9 February 2006 Paper

A closer look at texture metrics for visualization

Haleh Hagh-Shenas, Victoria Interrante, Cheong Hee-Park

Proceedings Volume 6057, 60570W (2006) https://doi.org/10.1117/12.643150

KEYWORDS: Visualization, Image classification, Visual process modeling, Statistical analysis, Electronic imaging, Computer graphics, Fourier transforms, Human subjects, Computer science, Human vision and color perception

Read Abstract +

Proceedings Article | 17 June 2003 Paper

Showing shape with texture: two directions seem better than one

Sunghee Kim, Haleh Hagh-Shenas, Victoria Interrante

Proceedings Volume 5007, (2003) https://doi.org/10.1117/12.477368

KEYWORDS: Visualization, Systems modeling, Spatial frequencies, Error analysis, Data modeling, Statistical analysis, Convolution, 3D modeling, Visual process modeling, Radiotherapy

Read Abstract +

Studies have shown that observers' judgment of surface orientation and curvature is affected by the presence of surface texture pattern. However, the question of designing a texture pattern that does not hide the surace information nor does convey a misrepresentation of the surface remains unsolved. The answer to this question has important potential imapct across a wide range of visualization application. Molecular modeling and radiation therapy are among the many fields that are in need of accurately visualizing their data and could benefit from such methods. Over the past several years we have carried out a series of experiments to investigate the impact of various texture pattern characteristics on shape perception. In this paper we report the result of our most recent study. The task in this study was adjusting surface attitude probes under three different texture conditions and a control condition in which no texture was present. We later compare the performances of the subjects. The three texture conditions were: a doubly oriented texture in which approximately evenly spaced lines followed both of the principal directions, a singly oriented texture in which lines followed only the first principal direction, and a singly oriented line integral convolution. Over a series of 200 trials (4 texture conditions, 10 surface probe locations * five repeated measures) a total of five naive participants were asked to adjust a circular probe. The probes were randomly located on an arbitrary curved surface and its perpendicular extension appeared to be oriented in the direction of the surface normal. An analysis of the results showed that the performance was best in the two directional texture condition. Performances were further decreased in one directional and no texture conditions (in that order). The paper is organized as follows. In Section 1 we briefly describe the motivation for our work. In Section 2 we describe our experimental methods, including a brief summary of the process of the stimuli preparation and a detailed presentation of statistic analysis of our experimental results. In Section 3 we discuss the implications of our findings and in the last section we will talk about our future plans.

Proceedings Article | 30 May 2002 Paper

Conveying 3D shape with texture: recent advances and experimental findings

Victoria Interrante, Sunghee Kim, Haleh Hagh-Shenas

Proceedings Volume 4662, (2002) https://doi.org/10.1117/12.469515

KEYWORDS: Algorithm development, Light sources and illumination, 3D image processing, Distortion, Image processing, Computer science, Lighting standards, Switches, Volume rendering, Solids

Read Abstract +

If we could design the perfect texture pattern to apply to any smooth surface in order to enable observers to more accurately perceive the surface's shape in a static monocular image taken from an arbitrary generic viewpoint under standard lighting conditions, what would the characteristics of that texture pattern be? In order to gain insight into this question, our group has developed an efficient algorithm for synthesizing a high resolution texture pattern, derived from a provided 2D sample, over an arbitrary doubly curved surface in such a way that the orientation of the texture is constrained to follow a specified underlying vector field over the surface, at a per-pixel level, without evidence of seams or projective distortion artifacts. In this paper, we report the findings of a recent experiment in which we attempt to use this new texture synthesis method to assess the shape information carrying capacity of two different types of directional texture patterns (unidirectional and bi-directional) under three different orientation conditions (following the first principal direction, following a constant uniform direction, or swirling sinusoidally in the surface). In a four alternative forced choice task, we asked participants to identify the quadrant in which two B-spline surfaces, illuminated from different random directions and simultaneously and persistently displayed, differed in their shapes. We found, after all subjects had gained sufficient training in the task, that accuracy increased fairly consistently with increasing magnitude of surface shape disparity, but that the characteristics of this increase differed under the different texture orientation conditions. Subjects were able to more reliably perceive smaller shape differences when the surfaces were textured with a pattern whose orientation followed one of the principal directions than when the surfaces were textured with a pattern that either gradually swirled in the surface or followed a constant uniform direction in the tangent plane regardless of the surface shape characteristics. These findings appear to support our hypothesis that anisotropic textures aligned with the first principal direction may facilitate shape perception, for a generic view, by making more, reliable information about the extent of the surface curvature explicitly available to the observer than would be available if the texture pattern were oriented in any other way.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years