yusuke1997/dblp-id-title huggingface dataset:
Multi-Layer Skeleton Fitting for Online Human Motion Capture
Not Just Alluvial: Towards a More Comprehensive Visual Analysis of Data Partition Sequences
Simultaneous and Consistent 3D Reconstruction of Multiple Views with Altering Search Path and Occlusion Modeling
Efficient Subsurface Scattering Simulation for Time-of-Flight Sensors
Thinning Mesh Animations
Morphable Models for the Analysis and the Synthesis of Images
Depth-Buffer based Navigation
Consistent Filtering of Videos and Dense Light-Fields Without Optic-Flow
Animating a Camera for Viewing a Planar Polygon
Hierarchical Radiosity with Global Refinement
Cost-effective Feature Enhancement for Volume Datasets
Bias Correction in Photometric Stereo using Control Points
ACUT: Out-Of-Core Delaunay Triangulation of Large Terrain Data Sets
Computing the Weighted Flow Complex
Variational Optical Flow from Alternate Exposure Images
Facial Reconstruction Using Volumetric Data
Fast and Flexible High-Quality Texture Filtering With Tiled High-Resolution Filters
A Taxonomy of Integration Techniques for Spatial and Non-Spatial Visualizations
Hierarchical Additive Poisson Disk Sampling
Out-of-Core Particle Tracing for Monte Carlo Rendering of Finite-Time Lyapunov Exponents
Out-of-Core Simplification with Guaranteed Error Tolerance
Reconfigurable Snapshot HDR Imaging Using Coded Masks and Inception Network
Volume-preserving Mesh Skinning
The Great Wall of Space-Time
An Image Algebra Accepting Image Models and Image Transforms
Fast and Accurate Ray-Voxel Intersection Techniques for Iso-Surface Ray Tracing
Variable Length Coding for GPU-Based Direct Volume Rendering
A taxonomy of visual recognition
Application of Tensor Approximation to Multiscale Volume Feature Representations
The Inverse Warp: Non-Invasive Integration of Shear-Warp Volume Rendering into Polygon Rendering Pipelines
A Thin Shell Approach to the Registration of Implicit Surfaces
A Framework for Axis Breaks in Charts
Measuring BRDFs of Immersed Materials
GPU-accelerated Interactive Material Aging
A Moving Least Squares Material Point Method for Varied Porous Material Interactions and Non-sticky Coupling of Phases
Digital Mammography: Gabor Filters for Detection of Microcalcifications
Markov Chain Driven Multi-Dimensional Visual Pattern Analysis with Parallel Coordinates
Active Areas: On Interaction in a Virtual Environment
Axes Bundling and Brushing in Star Coordinates
Dense and Scalable Reconstruction from Unstructured Videos with Occlusions
Direct Visualization of Particle-Partition of Unity Data
Vector-to-Closest-Point Octree for Surface Ray-Casting
Using Feature Flow Fields for Topological Comparison of Vector Fields
Real-time Rendering of Stack-based Terrains
Dynamic Time Warping Based 3D Contours
A Probabilistic Model-based Template Matching Approach for Robust Object Tracking in Real-Time
Reducing Artifacts in Industrial 3D Computed Tomography (CT)
An Adaptive Sampling Scheme for Real-Time Subsurface Scattering
One-sided Stability of MAT and Its Applications
Silhouette-Based Multiple-View Camera Calibration
Spatial Scalable JPEG2000 Transcoding and Tracking of Regions of Interest for Video Surveillance
Appearance Bending: A Perceptual Editing Paradigm for Data-Driven Material Models
Piecewise Linear Approximation of Signed Distance Fields
Compression of Isosurfaces
GPU-Based Streamlines for Surface-Guided 3D Flow Visualization
Digitizing the Parthenon: Estimating Surface Reflectance Properties of a Complex Scene under Captured Natural Illumination
Memory Efficient Billboard Clouds for BTF Textured Objects
Hardware Accelerated Terrain Rendering by Adaptive Slicing
Portal-Based Path Perturbation for Metropolis Light Transport
The Parallel Eigenvectors Operator
Astray: A Performance-Portable Geodesic Ray Tracer
Comparative Visualization of Two-Dimensional Flow Data Using Moment Invariants
Direct Image Registration without Region of Interest
GPU-Parallel Constant-Time Limit Evaluation of Catmull-Clark Solids
On-the-Fly Adaptive Subdivision Terrain
Efficient Lifted Relaxations of the Quadratic Assignment Problem
Non-iterative Camera Calibration Procedure Using A Virtual Camera
Sparse versus Dense Approaches in Computer Vision
Sampling feature points for contour tracking with graphics hardware
Progressive path tracing with lightweight local error estimation
The Recognition of Ethnic Groups based on Histological Skin Properties
Learning a Perceptual Quality Metric for Correlation in Scatterplots
20th International Symposium on Vision, Modeling, and Visualization, VMV 2015, Aachen, Germany, October 7-10, 2015
Voxelisation: Modelling for Volume Graphics
Image Based Reconstruction and Interaction of 2D Vector Fields
Maximum Detector Response Markers for SIFT and SURF
Image Processing and Modeling of the Laryngectomee Substitute Voice
Efficient GPU Based Sampling for Scene-Space Video Processing
A Mixed Shape Space for Fast Interpolation of Articulated Shapes
Frequency-Domain Upsampling on a Body-Centered Cubic Lattice for Efficient and High-Quality Volume Rendering
Signal Analysis and Geometry in Immersive Sensing
Motion Consistency for Image-Based Rendering
8th International Fall Workshop on Vision, Modeling, and Visualization, VMV 2003, München, Germany, November 19-21, 2003
Generation of Smooth and Accurate Surface Models for Surgical Planning
PlenopticPoints: Rasterizing Neural Feature Points for High-Quality Novel View Synthesis
Efficient Generation of 3-D Models Out of Depth Maps
A Comparison of Weighted Average Methods for Computing Normals to Marching Cubes Isosurfaces
Depth Driven Photometric and Geometric Image Registration for Real-Time Stereo Systems
Semi-Automatic Manufacturing of Customized Hearing Aids Using a Feature Driven Rule-based Framework
Analysis of Community-contributed Space- and Timereferenced Data by Example of Panoramio Photos
ADB-Trees: Controlling the Error of Time-Critical Collision Detection
Improving Stability and Compactness in Street Layout Visualizations
Fast Acquiring and Analysis of Three Dimensional Laser Range Data
Matting with Sequential Pair Selection Using Graph Transduction
Shape Median Based on Symmetric Area Differences
Efficient Boundary Detection and Transfer Function Generation in Direct Volume Rendering
Graphics-Accelerated Panoramic Mosaicking from a Video Camera Array
Internal Labels as Shape Cues for Medical Illustration
Reducing Computation Time in a Reaction-Diffusion Stereo Algorithm
Instant Level-of-Detail
Real-Time Caustics Using Cascaded Image-Space Photon Tracing
Hardware Accelerated Interactive Stipple Drawing of Polygonal Objects
Patch-Graph Reconstruction for Piecewise Smooth Surfaces
Art-Inspired Modeling and Visualization
A New Robust Bayesian Method for the Affine F-Matrix Estimation
Mobile Image Retargeting
Local and Global Analysis for Point Cloud Data
Exemplar-Based Surface Texture
3D Scanning Cultural Heritage Artifacts: Potentialities and Issues
Adaptive surface decomposition for the distance computation of arbitrarily shaped objects
Perceptualization: Techniques for Efffective Image Generation Visualization and Communication of Information
Efficient Iterative Solvers for Angle Based Flattening
WithTeeth: Denture Preview in Augmented Reality
Non-invasive attitude detection for full-body interaction in MEDIATE, a multisensory interactive environment for children with autism
Hardware Accelerated Texture Extraction for a Photo-Realistic Predictive Display
Neural Fields for Interactive Visualization of Statistical Dependencies in 3D Simulation Ensembles
Augmented Visualization of the Patient's Organs through a SlidingWindow
A Cluster Hierarchy-based Volume Rendering Approach for Interactive Visual Exploration of Multi-variate Volume Data
Propagation of Shape Parameterisation for the Construction of a Statistical Shape Model of the Left Ventricle
Static Visualization of Unsteady Flows by Flow Steadification
Kinematic ICP for Articulated Template Fitting
Object Tracking and Pose Estimation Using Light-Field Object Models
Level-of-Detail for Production-Scale Path Tracing
VR Based Adaptive Simulation in Estimation of Whiplash Injuries
Global Illumination using Parallel Global Ray-Bundles
Stochastic Convolutional Sparse Coding
Progressive Compression and Rendering of Light Fields
Light Field Imaging through Household Optics
3D Shape Cropping
On the Suitability of Connectivity-Extended Local Embedding for Drawing Multivariate Graphs
A Generalized 2D and 3D Multi-Sensor Data Integration Approach based on Signed Distance Functions for Multi-Modal Robotic Mapping
Visualization of Cardiac Blood Flow Using Anisotropic Ambient Occlusion for Lines
Towards unsupervised reconstruction of architectural models
Improving Layout Quality by Mixing Treemap-Layouts Based on Data-Change Characteristics
Visualization of the Pharyngoesophageal Mucosa During Tracheoesophageal Phonation
Robust Dense Disparity Estimation Using Hierarchical Adaptive Curve Matching
A Mass Spring System Supporting 2D Modelling of 3D Components
An Efficient Point Location Method for Visualization in Large Unstructured Grids
Gerbil - A Novel Software Framework for Visualization and Analysis in the Multispectral Domain
LiteMaker: Interactive Luminaire Development using Progressive Photon Tracing and Multi-Resolution Upsampling
Head Modeling with Camera Autocalibration and Deformation
Interactive Comparative Visualization of Multimodal Brain Tumor Segmentation Data
Topology-Caching for Dynamic Particle Volume Raycasting
Real-time Reflective and Refractive Novel-view Synthesis
Erosion and Dilation on 2-D and 3-D Digital Images: A New Size-Independent Approach
Segmentation-Based Postprocessing in Real-Time Immersive Video Conferencing
Multi-view Geometry Estimation for Light Field Compression
A Semi-Automated Method for Subject-Specific Modeling of the Spinal Canal from Computed Tomography Images and Dynamic Radiographs
AVDT - Automatic Visualization of Descriptive Texts
Watch these Lips: Motion Segmentation of Human Speech and Voice Organs
Hierarchical Volume Visualization of Brain Anatomy
Stack Implementation on Programmable Graphics Hardware
How Fusion of Multiple Views Can Improve Object Recognition in Real-World Environments
Advanced Data Terms for Variational Optic Flow Estimation
HandFlow: Quantifying View-Dependent 3D Ambiguity in Two-Hand Reconstruction with Normalizing Flow
Automatic Image-Based Scene Model Acquisition and Visualization
Fitting a Morphable Model to Pose and Shape of a Point Cloud
Pseudo-Normals for Signed Distance Computation
Greedy Image Approximation for Artwork Generation via Contiguous Bézier Segments
Motion Vector Estimation for Tracking of Hands in Video Based Industrial Safety Applications
Wavelet Shrinkage of Turbulent Flow Fields Within a Finite-Volume Flow Simulation Program
Analysis of Vortex Merge Graphs
Visualizing Dissections of the Heart in a Dataflow-based Shader Framework for Volume Rendering
17th International Workshop on Vision, Modeling, and Visualization, VMV 2012, Magdeburg, Germany, November 12-14, 2012
Is it Necessary to Model the Matrix Degrading Enzymes for Simulating Tumour Growth?
QEM-Filtering: A New Technique for Feature-Sensitive Terrain Mesh Simplification
Ray Tracing for Recirculation Surfaces
Adaptive Level-of-Precision for GPU-Rendering
Multiresolution Implicit Object Modeling
SBL Mesh Filter: A Fast Separable Approximation of Bilateral Mesh Filtering
Real-time Full-body Visual Traits Recognition from Image Sequences
Registration of Temporal Ultrasonic Image Sequences Using Markov Random Fields
Geospatial Topographic Attribute Maps
LayoutExOmizer: Interactive Exploration and Optimization of 2D Data Layouts
Reconstruction of Variational Implicit Surfaces from Parallel Contours for Medical Imaging
Design of a Multimodal Rendering System
Automatic Detection and Recognition of Engineered Nanoparticles in SEM Images
A Cluster Based Stable Multicast Routing Protocol in Ad Hoc Network
Reconfigurable NC-OFDM Processor for 5G Communications
Actors for Mobile Ad-Hoc Networks
Efficient Client-to-Client Password Authenticated Key Exchange
Communication Model Exploration for Distributed Embedded Systems and System Level Interpretations
A New Buffer Planning Algorithm Based on Room Resizing
Power-Aware Position Vector Routing for Wireless Sensor Networks
WPAN Platform Design in Handset Integrating Cellular Network and Its Application to Mobile Games
An Architecture Framework for Measuring and Evaluating Packet-Switched Voice
Building Graphical Model Based System in Sensor Networks
The 3DMA Middleware for Mobile Applications
IEEE/IFIP 8th International Conference on Embedded and Ubiquitous Computing, EUC 2010, Hong Kong, China, 11-13 December 2010
Point-to-Multipoint Ultrasonic Communication Modem for Ubiquitous Underwater Wireless Sensor Networks
SystemC-Based Design Space Exploration of a 3D Graphics Acceleration SoC for Consumer Electronics
Research Issues and Challenges to Advance System Software for Multicore Processors and Data-Intensive Applications
A Dependability Management Mechanism for Ubiquitous Computing Systems
ORAID: An Intelligent and Fault-Tolerant Object Storage Device
Universal Designated Verifier Ring Signature (Proof) Without Random Oracles
Energy-Aware Task Allocation for Large Task Sets on Heterogeneous Multiprocessor Systems
Task-I/O Co-scheduling for Pfair Real-Time Scheduler in Embedded Multi-core Systems
Tree-Based Classification Algorithm for Heterogeneous Unique Item ID Schemes
An Intelligent Event-Driven Interface Agent for Interactive Digital Contents in Ubiquitous Environments
Parallel Network Intrusion Detection on Reconfigurable Platforms
Reassignment Scheme of an RFID Tag's Key for Owner Transfer
Job Phasing Aware Preemption Deferral
A Platform for Integrating Physical Devices in the Internet of Things
Fast and Scalable Thread Migration for Multi-core Architectures
Formal Trust Specification in Service Workflows
A Software Framework for Energy and Performance Tradeoff in Fixed-Priority Hard Real-Time Embedded Systems
Embedded and Ubiquitous Computing, International Conference EUC 2004, Aizu-Wakamatsu City, Japan, August 25-27, 2004, Proceedings
An On-line Reliability Emulation Framework
Energy-Efficient Target Localization Based on a Prediction Model
Context Reasoning Technologies in Ubiquitous Computing Environment
Parallel Embedded Systems: Optimizations and Challenges
Performance Measuring and Comparing of Virtual Machine Monitors
PPF Model with CTNT to Defend Web Server from DDoS Attack
Design of a Middleware and HIML (Human Interaction Markup Language) for Context Aware Services in a Ubiquitous Computing Environment
Energy Efficient PNC Selection Procedure for the IEEE 802.15.3-Based HR-WPAN
A GML-Based Mobile Device Trace Monitoring System
Context-Aware State Management for Ubiquitous Applications
LaMSM: Localization Algorithm with Merging Segmented Maps for Underwater Sensor Networks
A Server-Side Pre-linking Mechanism for Updating Embedded Clients Dynamically
An Optimal Distribution of Data Reduction in Sensor Networks with Hierarchical Caching
AdaptUbiFlow: Selection and Adaptation in Workflows for Ubiquitous Computing
Perturbative Time and Frequency Allocations for RFID Reader Networks
PSSBP: A Privacy-preserving Scope-query Searchable Encryption Scheme Based on Blockchain for Parking Lots Sharing in Vehicular Networks
Efficient RFID Authentication Scheme for Supply Chain Applications
Probabilistic Trust Management in Pervasive Computing
Usage-Aware Search in Peer-to-Peer Systems
Evaluation of Partitioning Methods for Stream Applications on a Heterogeneous Multi-core Processor Simulator
A GA-based Systematic Message Scheduling Method for Time-Triggered CAN
A Domain-Specific Language for the Specification of Adaptable Context Inference
Key Sharing in Hierarchical Wireless Sensor Networks
Dithering-Based Power and Thermal Management on FPGA-Based Multi-core Embedded Systems
Greedy Routing on Hierarchical Clusters
Control-Flow Checking Using Branch Instructions
An OSGi Based RFID Complex Event Processing System
Automatic Integration of Non-Bus Hardware IP into SoC-Platforms for Use by Software
Using Early Power and Timing Estimations of Massively Heterogeneous Computation Platforms to Create Optimized HPC Applications
Application-Driven Customization of an Embedded Java Virtual Machine
Modeling and Robust Control for Trusted Web Server
Non-uniform Set-Associative Caches for Power-Aware Embedded Processors
A Java-Based RFID Service Framework with Semantic Data Binding Between Real and Cyber Spaces
An Accurate Architectural Simulator for ARM1136
Communications via Systems-on-Chips Clustering in Large-Scaled Sensor Networks
Realizing Efficient Execution of Dataflow Actors on Manycores
UPS - An Ubiquitous Proximity eService for Trust Collaboration
Efficient Error Control for Scalable Media Transmission over 3G Broadcast Networks
Layered Peer to Peer Streaming Using Hidden Markov Models
An Efficient Mutual Authentication Protocol on RFID Tags
Variable-Radii Method Based on Probing Mechanism (VRPM): An Energy Conservation Method for Wireless Active Sensor Networks
Evaluation of Models for Analyzing Unguided Search in Unstructured Networks
A Run-Time Partitioning Algorithm for RTOS on Reconfigurable Hardware
Optimal Allocation of I/O Device Parameters in Hardware and Software Codesign Methodology
Runtime Adaptation of Embedded Tasks with A-Priori Known Timing Behavior Utilizing On-Line Partner-Core Monitoring and Recovery
A Ticket Based Binding Update Authentication Method for Trusted Nodes in Mobile IPv6 Domain
X-Tree Diff+: Efficient Change Detection Algorithm in XML Documents
The Analysis and Simulation of a Hybrid Video Broadcast Architecture
u-KoMIPS: A Medical Image Processing System in a Ubiquitous Environment
Research and Design of Shared Resources Competition Solution among Hardware-Software Tasks based on Unified Scheduling
Accelerating Montgomery Modulo Multiplication for Redundant Radix-64k Number System on the FPGA Using Dual-Port Block RAMs
The Challenges and Opportunities in Transparent Computing
Contextual Interfacing: A Sensor and Actuator Framework
PosCFS: An Advanced File Management Technique for the Wearable Computing Environment
A Signature-based Grid Index Design for RFID Main-Memory Databases
A Novel Virtual Grid Experiment Method in MedImGrid
An Abstract Model of a Coordination Protocol Using the UPPAAL Model Checker
A Reverse AODV Routing Protocol in Ad Hoc Mobile Networks
Optimizing Address Assignment for Scheduling Embedded DSPs
Real-Time Loop Scheduling with Energy Optimization Via DVS and ABB for Multi-core Embedded System
Invalidation for CORBA Caching in Wireless Devices
Cryptanalysis of a Generalized Anonymous Buyer-Seller Watermarking Protocol of IWDW 2004
Norms Enforcement as a Coordination Strategy in Ubiquitous Environments
A Dynamic Trust Establishment and Management Framework for Wireless Sensor Networks
Folded Fat H-Tree: An Interconnection Topology for Dynamically Reconfigurable Processor Array
Performance Analysis of DS-BPAM UWB System over Fading Channels - Uncoded and Coded Schemes
Analysis of Connectivity for Sensor Networks Using Geometrical Probability
Reliable Key Establishment Scheme Exploiting Unidirectional Links in Wireless Sensor Networks
Inter-sector Interference Mitigation Method in Triple-Sectored OFDMA Systems
RADAR: Rate-Alert Dynamic RTS/CTS Exchange for Performance Enhancement in Multi-Rate Wireless Networks
Thermal-Aware Code Transformation across Functional Units
Evaluation of a Systematic Approach in Variant Management for Safety-Critical Systems Development
Transferring Ontologies between Mobile Devices and Knowledge-Based Systems
Adaptive GTS Allocation Scheme based on IEEE 802.15.4 for Underwater Acoustic Sensor Networks
Selective Collision Based Medium Access Control Protocol for Proactive Protection of Privacy for RFID
An Analytical Model for Broadcasting by Self Pruning in Wireless Ad Hoc Networks
On the Security of Non-Linear HB (NLHB) Protocol against Passive Attack
Crown: An Efficient and Stable Distributed Resource Lookup Protocol
Assured-Timeliness Integrity Protocols for Distributable Real-Time Threads with in Dynamic Distributed Systems
Low-Cost and Strong-Security RFID Authentication Protocol
Global State Detection Based on Peer-to-Peer Interactions
Digital Ortho-image Production for Web GIS Applications
Search Based Model in the Loop Testing for Cyber Physical Systems
Automatic Generation and Enforcement of Security Contract for Pervasive Application
A Virtual Reality Based System for Remote Maintenance of Rotating Machinery
A Strong Identity Based Key-Insulated Cryptosystem
Towards Successive Privacy Protection in Sensor Networks
A New Simple Authenticated Key Agreement and Protected Password Change Protocol
User Preference Based Service Discovery
OCO: A Multi-channel MAC Protocol with Opportunistic Cooperation for Wireless Sensor Networks
Optimizing Nested Loops with Iterational and Instructional Retiming
Performance Analysis of IP Micro-mobility Protocols in Single and Simultaneous Movements Scenario
Scalable Uniformly-Distributed Clustering Mechanism for Sensor Networks
Implementation of Cloud Computing Environment for Discrete Event System Simulation using Service Oriented Architecture
Semi-Partitioned Scheduling of Fork-Join Tasks Using Work-Stealing
Palpability Support Demonstrated
An RFID System Based MCLT System with Improved Privacy
Adaptive Error Recovery in cdma2000 1xEV-DO Mobile Broadcast Networks
Reliable Broadcast Message Authentication in Wireless Sensor Networks
An Improved EMD Embedding Scheme Based on Secret Image Difference
IMAC: An Interference-Aware Duty-Cycle MAC Protocol for Wireless Sensor Networks Employing Multipath Routing
Architectural Support for Reducing Parallel Processing Overhead in an Embedded Multiprocessor
Hardware Support for Efficient Sparse Matrix Vector Multiplication
20th IEEE International Conference on Embedded and Ubiquitous Computing, EUC 2022, Wuhan, China, December 9-11, 2022
A Chinese Mobile Phone Input Method Based on the Dynamic and Self-study Language Model
Cooperative Task Offloading in Cybertwin-Assisted Vehicular Edge Computing
19th IEEE International Conference on Embedded and Ubiquitous Computing, EUC 2021, Shenyang, China, October 20-22, 2021
Who Is Going to Be the Next BitTorrent Peer Idol?
Methods and Algorithms for the Interaction of Residential Smart Buildings with Smart Grids
Dynamic Routing and Wavelength Assignment in WDM Networks with Ant-Based Agents
MDR-Based Framework for Sharing Metadata in Ubiquitous Computing Environment
Integrated Multimedia Understanding for Ubiquitous Intelligence Based on Mental Image Directed Semantic Theory
A Session Mobility Scheme for Seamless VOD Service in Ubiquitous Environments
Trimming Approach of Robust Clustering for Smartphone Behavioral Analysis
Vulnerability of an RFID Authentication Protocol Proposed in at SecUbiq 2005
A Novel Approach for Sharing White Board Between PC and PDAs with Multi-users
An Intelligent Sensor for Fingerprint Recognition
Pipelined Bidirectional Bus Architecture for Embedded Multimedia SoCs
A Self-Adaptive System for Vehicle Information Security Applications
Custom Instruction Generation Using Temporal Partitioning Techniques for a Reconfigurable Functional Unit
2008 IEEE/IPIP International Conference on Embedded and Ubiquitous Computing (EUC 2008), Shanghai, China, December 17-20, 2008, Volume II: Workshops
A Distributed Trust Model for Securing Mobile Ad Hoc Networks
Power Management in Real Time Embedded Systems through Online and Adaptive Interplay of DPM and DVFS Policies
Bilateration: An Attack-Resistant Localization Algorithm of Wireless Sensor Network
A Hardware/Software Co-design and Co-verification on a Novel Embedded Object-Oriented Processor
Checkpointing for the Reliability of Real-Time Systems with On-Line Fault Detection
AoTI Minimization for Multi-Type Data Sampling in Industrial Wireless Sensor Networks
PerSON: A Framework for Service Overlay Network in Pervasive Environments
Power-Aware Instruction Scheduling
Security in P2P Networks: Survey and Research Directions
An Energy Aware, Cluster-Based Routing Algorithm for Wireless Sensor Networks
A Context-Aware System for Smart Home Applications
QT-CBP: A New RFID Tag Anti-collision Algorithm Using Collision Bit Positioning