bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual Differences in Inhibitory Control and Children's Theory of Mind
Authors: Carlson Stephanie M. , Moses Louis J.
Published: March 2003

This research examined the relation between individual differences in inhibitory control (IC; a central component of executive functioning) and theory‐of‐mind (ToM) performance in preschool‐age children. Across two sessions, 3‐ and 4‐year‐old children (N=107) were given multitask batteries measuring IC and ToM. Inhibitory control was strongly related to ToM, r=.66, p < .001. This relation remained significant controlling for age, gender, verbal ability, motor sequencing, family size, and performance on pretend‐action and mental state control tasks. Inhibitory tasks requiring a novel response in the face of a conflicting prepotent response (Conflict scale) and those requiring the delay of a prepotent response (Delay scale) were significantly related to ToM. The Conflict scale, however, significantly predicted ToM performance over and above the Delay scale and control measures, whereas the Delay scale was not significant in a corresponding analysis. These findings suggest that IC may be a crucial enabling factor for ToM development, possibly affecting both the emergence and expression of mental state knowledge. The implications of the findings for a variety of executive accounts of ToM are discussed.
When Groups Are Not Created Equal: Effects of Group Status on the Formation of Intergroup Attitudes in Children
Authors: Bigler Rebecca S. , Spears Brown Christia , Markell Marc
Published: March 2003

This study was designed to examine whether the presence of implicit links between social groups and high versus low status attributes affects the formation of intergroup attitudes. Elementary school children aged 7 to 12 years (N=91) were given measures of classification skill and self‐esteem, and assigned to one of three types of summer school classrooms in which teachers made (1) functional use of novel (“blue” and “yellow”) social groups that were depicted via posters as varying in status, (2) no explicit use of novel social groups that were, nonetheless, depicted as varying in status, or (3) functional use of novel social groups in the absence of information about status. After 6 weeks, children completed measures of intergroup attitudes. Results indicated that children's intergroup attitudes were affected by the status manipulation when teachers made functional use of the novel groups. Children who were members of high‐status (but not low‐status) groups developed in‐group biased attitudes.
Interparental Discord and Adolescent Adjustment Trajectories: The Potentiating and Protective Role of Intrapersonal Attributes
Authors: Davies Patrick , Windle Michael
Published: March 2003

This prospective study of 360 adolescent – mother dyads examined whether associations between marital discord and trajectories of adolescent depressive symptoms and delinquency varied as a function of three intrapersonal attributes: temperament, childhood behavior problems, and perceived family support. Difficult temperament (i.e., dysrhythmicity, poor task orientation) potentiated the effects of marital discord on adolescent trajectories of adjustment, whereas heightened perceptions of family support protected adolescents from the adverse effects of marital discord. Adolescents with behavior problem histories were initially less vulnerable to marital discord; however, the high levels of depressive symptoms exhibited by adolescents with childhood behavior problems persisted over time only when they were exposed to elevated marital discord. The effects of the moderators differed in terms of duration and course.
The Influence of Neighborhood Disadvantage, Collective Socialization, and Parenting on African American Children's Affiliation with Deviant Peers
Authors: Brody Gene H. , Conger Rand , Gibbons Frederick X. , Ge Xiaojia , McBride Murry Velma , Gerrard Meg , Simons Ronald L.
Published: March 2003

This study focused on hypotheses about the contributions of neighborhood disadvantage, collective socialization, and parenting to African American children's affiliation with deviant peers. A total of 867 families living in Georgia and Iowa, each with a 10‐ to 12‐year‐old child, participated. Unique contributions to deviant peer affiliation were examined using a hierarchical linear model. Community disadvantage derived from census data had a significant positive effect on deviant peer affiliations. Nurturant/involved parenting and collective socialization processes were inversely associated, and harsh/inconsistent parenting was positively associated, with deviant peer affiliations. The effects of nurturant/involved parenting and collective socialization were most pronounced for children residing in the most disadvantaged neighborhoods.
Perception of Kinetic Illusory Contours by Two‐Month‐Old Infants
Authors: Johnson Scott P. , Mason Uschi
Published: March 2003

Perception of kinetic illusory contours by 2‐month‐old infants was explored with sparse random‐dot displays depicting an illusory shape against a background. In Experiment 1, 24 infants were habituated to a shape specified by accretion and deletion of background texture and relative motion, and exhibited a novelty preference when presented with luminance‐defined familiar and novel shapes. Subsequent experiments explored kinetic cues in isolation. In Experiment 2 (n= 24), relative motion information was removed, leaving accretion and deletion of texture and luminance cues, and in Experiment 3 (n= 24), only relative motion information was available. In both these experiments the novelty preference obtained in Experiment 1 was replicated. Results from a control condition (n= 12) mitigated against the likelihood of an inherent preference for either of the test shapes. These findings reveal an early capacity to perceive shape solely from kinetic information, and suggest a mechanism geared toward spatiotemporal boundary formation that is functional shortly after birth. Theories of development of edge and motion discrimination are discussed.
Relation of Maternal Cognitive Stimulation, Emotional Support, and Intrusive Behavior during Head Start to Children’s Kindergarten Cognitive Abilities
Authors: Hubbs‐Tait Laura , Culp Anne McDonald , Culp Rex E. , Miller Carrie E.
Published: March 2003

The current study examined how parental cognitive stimulation, emotional support, and intrusiveness measured during children’s prekindergarten year were related to children’s verbal and nonverbal abilities 1 year later. Participants were 110 Head Start children and their caregivers from primarily rural and low‐income backgrounds. Analysis of children’s scores on the McCarthy Scales of Children’s Abilities confirmed the predictive utility of cognitive stimulation, emotional support, and intrusive behavior for perceptual scores (20% of the unique variance) as well as the predictive utility of emotional support and intrusive behavior for verbal scores (15% of the unique variance). Parental emotional support during guidance of problem solving (positive feedback) explained statistically significant unique variance in children’s perceptual scores beyond other measures of emotional support. Cognitive stimulation moderated the relation between positive feedback and perceptual scores. Although other syntactic forms of maternal utterances such as commands did not explain statistically significant unique variance in children’s scores beyond emotional support and intrusive behavior, mothers’ questions did. Specific policy implications of the effects are discussed.
Unique and Protective Contributions of Parenting and Classroom Processes to the Adjustment of African American Children Living in Single‐Parent Families
Authors: Brody Gene H. , Dorsey Shannon , Forehand Rex , Armistead Lisa
Published: March 2003

The unique contributions that parenting processes (high levels of monitoring with a supportive, involved mother‐child relationship) and classroom processes (high levels of organization, rule clarity, and student involvement) make to children’s self‐regulation and adjustment were examined with a sample of 277 single‐parent African American families. A multi‐informant design involving mothers, teachers, and 7‐ to 15‐year‐old children was used. Structural equation modeling indicated that parenting and classroom processes contributed uniquely to children’s adjustment through the children’s development of self‐regulation. Additional analyses suggested that classroom processes can serve a protective‐stabilizing function when parenting processes are compromised, and vice versa. Further research is needed to examine processes in both family and school contexts that promote child competence and resilience.
The Impact of Family Obligation on the Daily Activities and Psychological Well‐Being of Chinese American Adolescents
Authors: Fuligni Andrew J. , Yip Tiffany , Tseng Vivian
Published: March 2003

A daily diary method was employed to examine the extent to which Chinese adolescents in the United States assist and spend time with their families, and the implications of such behaviors for their involvement in other activities and psychological well‐being. Adolescents (N= 140) completed checklists in which they reported their activities and psychological well‐being every day for a period of 2 weeks. Adolescents showed a greater propensity to balance family obligations with their academic demands than with their social life with peers on a daily basis. Girls experienced slightly more daily conflict between activities than boys. Neither the extent of involvement in family obligations nor the balancing of family obligations with other activities were associated with psychological distress among adolescents. These findings demonstrate the complex manner in which adolescents from immigrant families attempt to combine their cultural traditions with selected aspects of American society on a daily basis. In contrast to the expectations of some observers, the youths in this study appeared to accomplish such an integration with little cost to their psychological well‐being.
Benefits of the Comprehensive Child Development Program as a Function of AFDC Receipt and SES
Authors: Ryan Carey S. , McCall Robert B. , Robinson Debbie R. , Groark Christina J. , Mulvey Laurie , Plemons Bradford W.
Published: March 2003

The benefits for children at the Pittsburgh site of the federal Comprehensive Child Development Program (CCDP) were examined as a function of family welfare status (Aid to Families with Dependent Children; AFDC) and SES. The CCDP was the largest attempt by the federal government to provide two‐generation, case‐managed, comprehensive services to low‐income families. Participating families could set their own goals and choose services to achieve them, but relatively few services were directed specifically at children. Results showed that more Pittsburgh families in the CCDP treatment group (N= 120) left AFDC than in the control group (N= 120), consistent with results from a national evaluation of the CCDP. Children whose families were on AFDC regardless of treatment group had lower mental test scores, even after controlling for family SES, a result suggesting that AFDC receipt over and above income level was associated with poorer child mental performance. The CCDP was associated with higher children’s mental scores plus improvements over time in achievement scores only for children in families who were not on AFDC, even after controlling for SES. Such parents were more likely to choose parenting and child goals and services, which in turn were associated with higher child mental scores. In contrast, parents who were on AFDC tended to choose adult‐centered goals and services, which did not benefit children. Therefore, in contrast to the national evaluation, which found no benefits of the CCDP for children, these analyses showed that the CCDP did produce benefits for children whose parents were not on AFDC, who tended to choose parenting and child services.
Preschoolers Are Sensitive to the Speaker’s Knowledge When Learning Proper Names
Authors: Birch Susan A. J. , Bloom Paul
Published: March 2003

Unobservable properties that are specific to individuals, such as their proper names, can only be known by people who are familiar with those individuals. Do young children utilize this “familiarity principle” when learning language? Experiment 1 tested whether forty‐eight 2‐ to 4‐year‐old children were able to determine the referent of a proper name such as “Jessie” based on the knowledge that the speaker was familiar with one individual but unfamiliar with the other. Even 2‐year‐olds successfully identified Jessie as the individual with whom the speaker was familiar. Experiment 2 examined whether children appreciate this principle at a general level, as do adults, or whether this knowledge may be specific to certain word‐learning situations. To test this, forty‐eight 3‐ to 5‐year‐old children were given the converse of the task in Experiment 1—they were asked to determine the individual with whom the speaker was familiar based on the speaker’s knowledge of an individual’s proper name. Only 5‐year‐olds reliably succeeded at this task, suggesting that a general understanding of the familiarity principle is a relatively late developmental accomplishment.
Guilt in Young Children: Development, Determinants, and Relations with a Broader System of Standards
Authors: Kochanska Grazyna , Gross Jami N. , Lin Mei‐Hua , Nichols Kate E.
Published: March 2003

In this comprehensive study of the early development of guilt, 106 children were observed in laboratory paradigms in which they were led to believe that they had damaged valuable objects, during two separate sessions at each of the assessments at 22, 33, and 45 months. The behavioral and affective components of guilt cohered significantly across the sessions, converged with each other, were stable across all the assessments, and corresponded modestly with maternal reports. Most components decreased with age, except for bodily tension, which increased. At 33 and 45 months, girls displayed more guilt than did boys. Children who were more fearful in typical fear‐inducing paradigms also displayed more guilt. Children of mothers who relied on more power‐assertive discipline, observed and self‐reported, displayed less guilt. Guilt related positively to the development of self at 18 months and to moral self at 56 months. Children who displayed more guilt were less likely to violate rules of conduct at 56 months. A mediational model was supported: Fearful temperament contributed to guilt proneness, which in turn served to inhibit children’s tendency to violate rules.
Obstetrical Complications and Violent Delinquency: Testing Two Developmental Pathways
Authors: Arseneault Louise , Tremblay Richard E. , Boulerice Bernard , Saucier Jean‐François
Published: March 2003

This study focused on the interaction between specific obstetrical complications and early family adversity in predicting violent behavior during childhood and adolescence, in a sample of 849 boys from low socioeconomic areas of Montréal, Canada. Obstetrical complication data from medical records were used to create three scales using a nonlinear principal component analysis followed by rotation. Family adversity and teacher‐rated physical aggression were assessed when the boys were in kindergarten and self‐reports of delinquency were collected when they were 17. Elevated scores on the Deadly Risk Situation scale of obstetrical complications (preeclampsia, umbilical cord prolapse, and induced labor) increased the risk of being violent at both 6 and 17 years of age, only among boys who grew up in high adverse familial environments. Moreover, this interaction partly accounted for the continuity between violence in childhood and adolescence. Interventions for young pregnant women from deprived environments and their babies are discussed in light of these results.
Predictability of Observed Mother–Child Interaction from Preschool to Middle Childhood in a High‐Risk Sample
Authors: Weinfield Nancy S. , Ogawa John R. , Egeland Byron
Published: March 2003

This study examined predictability of observed parent–child interaction from preschool to middle childhood in 283 mother–child dyads. Participants were welfare recipients enrolled in the Observational Study of the Job Opportunities and Basic Skills Training Program. Structured observational sessions were conducted both at preschool age and middle childhood, and were coded for maternal social behavior, child social behavior, and dyadic interaction. Analyses explored direct relations between the assessments; relations between the assessments with possible third‐variable influences, such as maternal literacy, covaried out; and moderated relations. Results indicated that observed mother–child interaction in middle childhood could be significantly predicted from observed interaction 4 years earlier. Risk status moderated the relations such that those families with greater risk factors tended to show more stability, although this stability was, at times, through maintaining suboptimal functioning.
Language at Work: Children's Gendered Interpretations of Occupational Titles
Authors: Liben Lynn S. , Bigler Rebecca S. , Krogh Holleen R.
Published: March 2003

A large literature has shown that children's beliefs and aspirations about occupations reflect cultural gender stereotypes. One channel that may create or sustain occupational stereotypes is language. Two studies were designed to examine whether children interpret occupational titles as gender specific or gender neutral. In Study 1, children (6‐ to 11‐year‐olds, N= 64) were asked directly if various job titles could be used for both men and women doing the job. In Study 2, children (6‐ to 10‐year‐olds, N= 51) were shown pictures of men and women engaged in job activities and asked which one(s) showed someone who could be called a(n). Titles were linguistically unmarked for gender (e.g., doctor), strongly marked (e.g., policeman), or weakly marked (e.g., postmaster). Marked titles were given in masculine and feminine forms. Findings reinforced past work showing that marked titles are exclusionary, revealed that some children harbor confusions about even unmarked titles, and demonstrated the mediating role of individual differences in attitudes. Implications for the changing lexicon and for educational programs are discussed.
Home Ownership and the Emotional and Behavioral Problems of Children and Youth
Authors: Boyle Michael H.
Published: March 2003

This study examined the impact of home ownership on the emotional–behavioral problems of children and youth ages 4 to 16 years. Data came from two large‐scale general population surveys conducted in the province of Ontario in 1983, the Ontario Child Health Study (N= 3,325) and the National Longitudinal Study of Children and Youth (N= 12,592). Results showed an inverse association between home ownership and ratings of emotional–behavioral problems. The net effects of home ownership expressed in standard units dropped from the .20 to .43 range for teacher and parent ratings to the .07 to .17 range, after controlling for socioeconomic variables. Furthermore, the concentration of home ownership in neighborhoods was not associated with ratings of child problem behavior in either study. Projects aimed at supporting home ownership among low‐income families may provide a means for improving the emotional and behavioral functioning of disadvantaged children.
Early Understanding of the Division of Cognitive Labor
Authors: Lutz Donna J. , Keil Frank C.
Published: March 2003

Two studies with 3–, 4–, and 5–year–olds (N= 104) examined whether young children can differentiate expertise in the minds of others. Study 1 revealed that all children in the sample could correctly attribute observable knowledge to familiar experts (i.e., a doctor and a car mechanic). Further, 4– and 5–year–olds could correctly attribute knowledge of underlying scientific principles to the appropriate experts. In contrast, Study 2 demonstrated that 3–, 4–, and 5–year–olds have difficulty making attributions of knowledge of scientific principles to unfamiliar experts. A computational analysis in Study 3 indicated that 4– and 5–year–olds’ successes on the first two studies could not be attributed to the way in which words co–occur in discourse. Overall, these studies showed that young children have a sense of the division of cognitive labor, albeit fragile.
Longitudinal Pathways to Competence and Psychological Adjustment among African American Children Living in Rural Single–Parent Households
Authors: Brody Gene H. , Murry Velma McBride , Kim Sooyeon , Brown Anita C.
Published: March 2003

A three–wave model linking maternal functioning to child competence and psychological adjustment was tested with 150 African American families living in the rural South. The children were 11 years old at Wave 1. Structural equation modeling indicated that maternal education and per capita income were linked with maternal psychological functioning (self–esteem, optimism, depression) at Wave 1, which forecast mothers’ competence–promoting parenting 1 year later at Wave 2. Competence–promoting parenting forecast child cognitive competence, social competence, and psychological adjustment 1 year later at Wave 3, indirectly through child self–regulation. The data were reanalyzed controlling for Wave 1 child competence and adjustment. All paths remained significant, indicating that the model accounted for change in child competence and adjustment across 2 years.
Privileged but Pressured? A Study of Affluent Youth
Authors: Luthar Suniya S. , Becker Bronwyn E.
Published: March 2003

The purpose of this study was to build on preliminary findings of unusually high internalizing symptoms and substance use among suburban high school students. The sample consisted of 302 sixth– and seventh–grade students in an affluent, suburban community. Findings corroborated expectations regarding several domains of vulnerability, showing (1) high rates of clinically significant depressive symptoms among older girls, (2) significant links between various internalizing symptoms and substance use among both boys and girls, and (3) peers’ approval of substance use among older boys. In exploring potential causes of distress in this suburban sample, associations were found for achievement pressures (particularly excessive perfectionistic strivings), and isolation from parents (particularly low perceived closeness to mothers). Findings of this study are discussed in terms of widespread stereotypes about affluent families, as well as implications for future research and preventive interventions for a subgroup of youth typically viewed as being at “low risk.”
Properties of School Chinese: Implications for Learning to Read
Authors: Shu Hua , Chen Xi , Anderson Richard C. , Wu Ningning , Xuan Yue
Published: March 2003

The properties of the 2,570 Chinese characters explicitly taught in Chinese elementary schools were systematically investigated, including types of characters, visual complexity, spatial structure, phonetic regularity and consistency, semantic transparency, independent and bound components, and phonetic and semantic families. Among the findings are that the visual complexity, phonetic regularity, and semantic transparency of the Chinese characters taught in elementary school increase from the early grades to the later grades: Characters introduced in the 1st or 2nd grade typically contain fewer strokes, but are less likely to be regular or transparent, than characters introduced in the 5th or 6th grade. The inverse relation holds when characters are stratified by frequency. Low–frequency characters tend to be visually complex, phonetically regular, and semantically transparent whereas high–frequency characters tend to be the opposite. Combined with other findings, the analysis suggests that written Chinese has a logic that children can understand and use.
Preschool Children Use Linguistic Form Class and Pragmatic Cues to Interpret Generics
Authors: Gelman Susan A. , Raman Lakshmi
Published: March 2003

Generic noun phrases (e.g., “Bats live in caves”) are important for expressing knowledge about abstract kinds. Past work has found that parents frequently use generic noun phrases in their speech to young children. However, little is known regarding how children understand these expressions, nor which cues signal generic meaning. The present set of 5 studies examined the influence of linguistic form class (e.g., “What color are dogs?” [generic] versus “What color are the dogs?” [nongeneric]) and of pragmatic context (e.g., “What color are they?” in the presence of either a single exemplar [generic] or multiple exemplars [nongeneric]). Participants were 2–year–olds (N = 42), 3–year–olds (N = 40), 4–year–olds (N = 40), and adults (N = 51). The data indicate that by 2 years of age, children use linguistic form class, and by 3 years of age, children use pragmatic context. These findings demonstrate that young children have begun to understand the distinction between generic and nongeneric noun phrases from a very young age, and that identification of generics is signaled not by formal or pragmatic cues alone, but by a combination of information from both language form and pragmatic context. It is suggested that children make use of multiple linguistic and conceptual cues to acquire and interpret generics.
A Secure Base in Adolescence: Markers of Attachment Security in the Mother–Adolescent Relationship
Authors: Allen Joseph P. , McElhaney Kathleen Boykin , Land Deborah J. , Kuperminc Gabriel P. , Moore Cynthia W. , O'Beirne–Kelly Heather , Kilmer Sarah Liebman
Published: March 2003

This study sought to identify ways in which adolescent attachment security, as assessed via the Adult Attachment Interview, is manifest in qualities of the secure base provided by the mother–adolescent relationship. Assessments included data coded from mother–adolescent interactions, test–based data, and adolescent self–reports obtained from an ethnically and socioeconomically diverse sample of moderately at–risk 9th and 10th graders. This study found several robust markers of adolescent attachment security in the mother–adolescent relationship. Each of these markers was found to contribute unique variance to explaining adolescent security, and in combination, they accounted for as much as 40% of the raw variance in adolescent security. These findings suggest that security is closely connected to the workings of the mother–adolescent relationship via a secure–base phenomenon, in which the teen can explore independence in thought and speech from the secure base of a maternal relationship characterized by maternal attunement to the adolescent and maternal supportiveness.
Reputation Formalization for an Information–Sharing Multi–Agent System
Authors: Carter Jonathan , Bitting Elijah , Ghorbani Ali A.
Published: March 2003

We propose that through the formalization of concepts related to trust, a more accurate model of trust can be implemented. This paper presents a new model of trust that is based on the formalization of reputation. A multidisciplinary approach is taken to understanding the nature of trust and its relation to reputation. Through this approach, a practical definition of reputation is adopted from sociological contexts and a model of reputation is designed and presented.

Reputation is defined as role fulfillment. To formalize reputation, it is necessary to formalize the expectations placed upon an agent within a particular multi–agent system (MAS). In this case, the agents are part of an information–sharing society. Five roles are defined along with the ways in which these roles are objectively fulfilled. Through the measurement of role fulfillment, a vector representing reputation can be developed. This vector embodies the magnitude of the reputation and describes the patterns of behavior associated with the direction of the vector.

Experiments are conducted to verify the sensibility of the proposed models for role fulfillment and overall reputation. The simulation results show that the roles, defined for building reputation in an information–sharing MAS environment, react to different agent and user actions in a manner consistent with the formal definitions.
Implicit Representations of Rough Surfaces
Authors: Hart John C.
Published: March 2003

Implicit surface techniques provide useful tools for modeling and rendering smooth surfaces. Deriving implicit formulations for fractal representations extends the scope of implicit surface techniques to rough surfaces. Linear fractals modeled by recurrent iterated function systems may be defined implicitly using either geometric distance or escape time. Random fractals modeled using Perlin's noise function are already defined implicitly when described as “hypertexture.”

Deriving new implicit formulae is only the first step. Unlike their smooth counterparts, rough implicit surfaces require special rendering techniques that do not rely on continuous differentiation of the defining function. Preliminary experiments applying blending operations to rough surfaces have succeeded in an initial attempt to overcome current challenges in natural modeling. The grafting of a stem onto the base of a linear fractal leaf continuously blends smooth detail into rough detail. The blend of two textured cylinders interpolates geometric bark across branching points in a tree.
Finally Everyone Can Work With Highly Complex 3D Models
Authors: Rossignac Jarek
Published: March 2003

In the past, access to 3D databases was restricted to few specialists having the appropriate CAD skills, software, and graphics hardware.

The availability of inexpensive graphics support on personal computers, the Internet’s impact on private and commercial communication, and the emergence of multimedia standards provide the basis for linking CAD databases with other personal productivity and communication tools and for making them accessible to everyone at home, in schools, in hospitals, or in the industry. For example, employees that have no design expertise, customers, and suppliers would benefit from having an easy access to the 3D databases of a company for: collaborative design review, 3D‐based multi‐media problem reports, collaborative problem solving and tracking, online training and documentation, internet‐based part purchasing and subcontracting, demonstration to customers, or advertising. This presentation will address three of the key issues that have so far limited the non‐specialist’s access to 3D databases.

First‐time or occasional non‐expert users need to become instant experts in 3D navigation through Virtual Environments or in the interactive manipulation of digital 3D models, so that they may immediately focus on their tasks, and not waste precious time learning and fighting an unnatural user interface. Immersive VR is not the panacea – other more effective techniques show promise.

The data complexity found in commercial CAD databases, especially in the automotive, aerospace, and construction industries, significantly exceeds the capabilities of any interactive graphics system. This situation is not likely to change, since the growth of the complexity and availability of 3D models outpaces the performance improvement of personal computers. Research on the automatic simplification of 3D models and on the use of levels of detail to accelerate the rendering of distant portions of the scene is growing rapidly.

The still limited bandwidth of internet communication channels prohibits a pervasive access to large amounts of 3D data. Recent 3D compression techniques reduce the storage requirements for polyhedral 3D models by two orders of magnitudes.
Interactive Rendering of Deforming NURBS Surfaces
Authors: Li Frederick W. B. , Lau Rynson W. H. , Green Mark
Published: March 2003

Non‐uniform rational B‐splines (NURBS) has been widely accepted as a standard tool for geometry representation and design. Its rich geometric properties allow it to represent both analytic shapes and free‐form curves and surfaces precisely. Moreover, a set of tools is available for shape modification or more implicitly, object deformation. Existing NURBS rendering methods include de Boor algorithm, Oslo algorithm, Shantz’s adaptive forward differencing algorithm and Silbermann’s high speed implementation of NURBS. However, these methods consider only speeding up the rendering process of individual frames. Recently, Kumar et al. proposed an incremental method for rendering NURBS surfaces, but it is still limited to static surfaces. In real‐time applications such as virtual reality, interactive display is needed. If a virtual environment contains a lot of deforming objects, these methods cannot provide a good solution. In this paper, we propose an efficient method for interactive rendering of deformable objects by maintaining a polygon model of each deforming NURBS surface and adaptively refining the resolution of the polygon model. We also look at how this method may be applied to multi‐resolution modelling.
Selective Pixel Transmission for Navigating in Remote Virtual Environments
Authors: Mann Yair , Cohen‐Or Daniel
Published: March 2003

This paper presents a technique to improve the performance of a walkthrough in remote virtual environments, where a scene is rendered jointly by the server and the client, in order to reduce the network requirements as much as possible. The client generates novel views by extrapolating a reference view based on the locally available geometric model, while the server transmits data necessary to prevent an accumulation of errors. Within this concept, we show that by transmitting only a selected subset of pixels, the quality of the extrapolated views can be improved while requiring less bandwidth. We focus on the selection process in which the visibility gaps between the reference view and novel view are detected, packed and transmitted compressed to the client.
Efficient Impostor Manipulation for Real‐Time Visualization of Urban Scenery
Authors: Sillion François , Drettakis George , Bodelet Benoit
Published: March 2003

Urban environments present unique challenges to interactive visualization systems, because of the huge complexity of the geometrical data and the widely varying visibility conditions. This paper introduces a new framework for real‐time visualisation of such urban scenes. The central concept is that of a dynamic segmentation of the dataset, into a local three‐dimensional model and a set of impostors used to represent distant scenery. A segmentation model is presented, based on inherent urban structure. A new impostor structure is introduced, derived from the level‐of‐detail approach. Impostors combine three‐dimensional geometry to correctly model large depth discontinuities and parallax, and textures to rapidly display visual detail. We present the algorithms necessary for the creation of accurate and efficient three‐dimensional impostors. The implementation of our algorithms allows interactive navigation in complex urban databases, as required by many applications.
Steering Image Generation with Wavelet Based Perceptual Metric
Authors: Gaddipatti Ajeetkumar , Machiraju Raghu , Yagel Roni
Published: March 2003

It is often the case that images generated by image synthesis algorithms are judged by visual examination. The user resorts to an iterative refinement process of inspection and rendering until a satisfactory image is obtained. In this paper we propose quantitative metrics to compare images that arise from an image synthesis algorithm. The intent is to be able to guide the refinement process inherent in image synthesis. The Mean‐Square‐Error (MSE) has been traditionally employed to guide this process. However, it is not a viable metric for image synthesis control. We propose the use of a wavelet based perceptual metric which incorporates the frequency response of the Human Visual System. A useful aspect of the wavelet based metric is its ability to selectively measure the changes to structures of different sizes and scales in specific locations. Also, by resorting to the use of wavelets of various degrees of regularity, one can seek different levels of smoothness in an image. It is rare that such level of control can be obtained from a metric other than a wavelet based metric. We show the usefulness of our metric by examining its effectiveness in providing insights for common operations of an image synthesis algorithm (e.g., blurring). We also provide some examples of its use in rendering algorithms frequently used in graphics.
Fast Collision Detection Algorithms with Applications to Particle Flow
Authors: Vemuri B. C. , Cao Y. , Chen L.
Published: March 2003

In this paper, we present efficient algorithms for collision detection of arbitrarily shaped rigid moving objects in a variety of interactive as well as non‐interactive environments. The algorithms primarily consist of two stages. The first stage involves finding candidate objects for possible collisions. The second stage involves detecting exact (within a prespecified tolerance) collision between these candidates. The primary data structure used in the algorithms is an octree. In the first stage, we build an octree for the enclosure containing the objects, which is used to detect possible collisions. Assuming spatial/temporal coherence i.e., that the particles move slowly or that the time sampling is fast enough, the average time complexity of this stage can be shown to be O(n) (excluding the time complexity for a one time octree construction), where n is the number of particles. In the second stage, we build a surface‐octree for each object. If the objects are convex and assuming coherence, the expected time complexity to detect precise (within a prespecified tolerance) collision for each pair is a constant (excluding the time complexity for a one time surface‐octree construction). Therefore, the overall expected time complexity for convex object collision detection is linear with respect to n. For the concave objects, complexity analysis is nontrivial to perform and instead we provide a very practical (almost linear time) algorithm. We apply our algorithms to particle flow simulations by simulating flow density conditions often arising in granular flows.
Animating Sand, Mud, and Snow
Authors: Sumner Robert W. , O'Brien James F. , Hodgins Jessica K.
Published: March 2003

Computer animations often lack the subtle environmental changes that should occur due to the actions of the characters. Squealing car tires usually leave no skid marks, airplanes rarely leave jet trails in the sky, and most runners leave no footprints. In this paper, we describe a simulation model of ground surfaces that can be deformed by the impact of rigid body models of animated characters. To demonstrate the algorithms, we show footprints made by a runner in sand, mud, and snow as well as bicycle tire tracks, a bicycle crash, and a falling runner. The shapes of the footprints in the three surfaces are quite different, but the effects were controlled through only five essentially independent parameters. To assess the realism of the resulting motion, we compare the simulated footprints to human footprints in sand.
Approximate Line Scan‐Conversion and Antialiasing
Authors: Chen Jim X. , Wang Xusheng
Published: March 2003

This paper presents an approximate multiple segment line scan‐conversion method — the Slope Table Method. The statistics show that the new method can increase the percentage of multiple segment lines (i.e., lines with more than one segment) in an N×N raster area from about 39% to more than 99%. In software implementation for scan‐conversion and antialiasing of randomly generated lines, this method is on average more than 6 times faster than Gupta's antialiasing line algorithm. Compared with other line scan‐conversion methods, the method may choose pixels which are not the closest to the line (i.e., error pixels). Here the paper demonstrates that the visual effect is acceptable in most applications with the error pixels.
An Information Theory Framework for the Analysis of Scene Complexity
Authors: Feixas Miquel , Del Acebo Esteve , Bekaert Philippe , Sbert Mateu
Published: March 2003

In this paper we present a new framework for the analysis of scene visibility and radiosity complexity. We introduce a number of complexity measures from information theory quantifying how difficult it is to compute with accuracy the visibility and radiosity in a scene. We define the continuous mutual information as a complexity measure of a scene, independent of whatever discretisation, and discrete mutual information as the complexity of a discretised scene. Mutual information can be understood as the degree of correlation or dependence between all the points or patches of a scene. Thus, low complexity corresponds to low correlation and vice versa. Experiments illustrating that the best mesh of a given scene among a number of alternatives corresponds to the one with the highest discrete mutual information, indicate the feasibility of the approach. Unlike continuous mutual information, which is very cheap to compute, the computation of discrete mutual information can however be quite demanding. We will develop cheap complexity measure estimates and derive practical algorithms from this framework in future work.
An Interactive Designing System with Virtual Sculpting and Virtual Woodcut Printing
Authors: Mizunoy S. , Okadayy M. , Toriwakiy J.
Published: March 2003

In this paper, we propose an interactive designing method and a system based on it to create 3D objects and 2D images. This system consists of two subsystems for virtual sculpting to create a 3D shape and virtual printing to produce a picture with a printing block. In the virtual sculpting subsystem, a user can form solid objects with curved surfaces as if sculpting them. The user operates virtual chisels, and can remove or attach arbitrary shapes of ellipsoids or cubes from or to the workpiece. A 3D object generated by virtual sculpting looks like a real wooden sculpture. If using a board as a workpiece, a user can generate a virtual printing block. In the virtual printing subsystem, a user can synthesize a woodcut printing image from the virtual printing block mentioned above, a virtual paper sheet, and a printing brush. The user can synthesize a realistic woodcut print with a procedure similar to the actual woodcut printing.
Generating Animatable 3D Virtual Humans from Photographs
Authors: Lee WonSook , Gu Jin , Magnenat‐Thalmann Nadia
Published: March 2003

We present an easy, practical and efficient full body cloning methodology. This system utilizes photos taken from the front, side and back of a person in any given imaging environment without requiring a special background or a controlled illuminating condition. A seamless generic body specified in the VRML H‐Anim 1.1 format is used to generate an individualized virtual human. The system is composed of two major components: face‐cloning and body‐cloning. The face‐cloning component uses feature points on front and side images and then applies DFFD for shape modification. Next a fully automatic seamless texture mapping is generated for 360° coloring on a 3D polygonal model. The body‐cloning component has two steps: (i feature points specification, which enables automatic silhouette detection in an arbitrary background (ii two‐stage body modification by using feature points and body silhouette respectively. The final integrated human model has photo‐realistic animatable face, hands, feet and body. The result can be visualized in any VRML compliant browser.
Interpolatory √3‐Subdivision
Authors: Labsik U. , Greiner G.
Published: March 2003

We present a new interpolatory subdivision scheme for triangle meshes. Instead of splitting each edge and performing a 1‐to‐4 split for every triangle we compute a new vertex for every triangle and retriangulate the old and the new vertices. Using this refinement operator the number of triangles only triples in each step. New vertices are computed with a Butterfly like scheme. In order to obtain overall smooth surfaces special rules are necessary in the neighborhood of extraordinary vertices. The scheme is suitable for adaptive refinement by using an easy forward strategy. No temporary triangles are produced here which allows simpler data structures and makes the scheme easy to implement.
Towards Blind Detection of Robust Watermarks in Polygonal Models
Authors: Benedens Oliver , Busch Christoph
Published: March 2003

We describe a Digital Watermarking system dedicated for embedding watermarks into 3D polygonal models. The system consists of three watermarking algorithms, one named Vertex Flood Algorithm (VFA) suitable for embedding fragile public readable watermarks with high capacity and offering a way of model authentication, one realizing affine invariant watermarks, named Affine Invariant Embedding (AIE) and a third one, named Normal Bin Encoding (NBE) algorithm, realizing watermarks with robustness against more complex operations, most noticeably polygon reduction. The watermarks generated by these algorithms are stackable. We shortly discuss the implementation of the system, which is realized as a 3D Studio MAX plugin.
Graceful Degradation of Collision Handling in Physically Based Animation
Authors: Dingliana John , O'Sullivan Carol
Published: March 2003

Interactive simulation is made possible in many applications by simplifying or culling the finer details that would make real‐time performance impossible. This paper examines detail simplification in the specific problem of collision handling for rigid body animation. We present an automated method for calculating consistent collision response at different levels of detail. The mechanism works closely with a system which uses a pre‐computed hierarchical volume model for collision detection.
Directional Discretized Occluders for Accelerated Occlusion Culling
Authors: Bernardini Fausto , Klosowski James T. , El‐Sana Jihad
Published: March 2003

We present a technique for accelerating the rendering of high depth‐complexity scenes. In a preprocessing stage, we approximate the input model with a hierarchical data structure and compute simple view‐dependent polygonal occluders to replace the complex input geometry in subsequent visibility queries. When the user is inspecting and visualizing the input model, the computed occluders are used to avoid rendering geometry which cannot be seen. Our method has several advantages which allow it to perform conservative visibility queries efficiently and it does not require any special graphics hardware. The preprocessing step of our approach can also be used within the framework of other visibility culling methods which need to pre‐select or pre‐render occluders. In this paper, we describe our technique and its implementation in detail, and provide experimental evidence of its performance. In addition, we briefly discuss possible extensions of our algorithm.
Computation of Irradiance from Triangles by Adaptive Sampling
Authors: Ureña C.
Published: March 2003

We introduce an algorithm for sample positioning in a planar triangle, which can be used to make numerical integration of an arbitrary function defined on it. This algorithm has some interesting properties which make it suitable for applications in the context of realistic rendering. We use an adaptive triangle partitioning procedure, driven by an appropriate measure of the error. The underlying variance is shown to be bounded, and in fact it can be controlled, so that it approaches the minimum possible value. We show results obtained when applying the method to irradiance computation, in the context of final‐gather algorithms. We also describe a C++ class which offers all required functionality, and we made available its source code.