Patric Ljung

• PhD
• Professor (Associate) at Linköping University

While the usefulness of 3D visualizations has been shown for a range of clinical applications such as treatment planning it still had difficulties in being adopted in widespread clinical practice. This chapter describes how multi-touch surfaces with patient-specific data have contributed to breaking this barrier, paving the way for adoption into cl...

Research has shown that learning outcomes can be improved by interactive visualization and exploration. This has led to the appearance of interactive installations on a range of platforms from handheld devices to large immersive dome theaters. One of the underlying principles of this data-driven visualization for broad audiences is the notion of th...

Visualization has evolved into a mature scientific field and it has also become widely accepted as a standard approach in diverse fields, including physics, life sciences, and business intelligence. However, despite its successful development, there are still many open research questions that require customized implementations in order to explore a...

Results of planetary mapping are often shared openly for use in scientific research and mission planning. In its raw format, however, the data is not accessible to non-experts due to the difficulty in grasping the context and the intricate acquisition process. We present work on tailoring and integration of multiple data processing and visualizatio...

BY COMBINING VISUALIZATION techniques with interactive multi-touch tables and intuitive user interfaces, visitors to museums and science centers can conduct self-guided tours of large volumetric image data. In an interactive learning experience, visitors become the explorers of otherwise invisible interiors of unique artifacts and subjects. Here, w...

A central topic in scientific visualization is the transfer function (TF) for volume rendering. The TF serves a fundamental role in translating scalar and multivariate data into color and opacity to express and reveal the relevant features present in the data studied. Beyond this core functionality, TFs also serve as a tool for encoding and utilizi...

An irregular ultrasound sampling grid is reconstructed to a three-dimensional grid for imaging. Volume data acquired with a helix transducer includes a fractional offset of data spaced along one dimension, resulting in the irregular ultrasound sampling grid. To determine a voxel value for a grid point on a uniform grid, two adjacent planes are iden...

LEARNING OBJECTIVES 1) Learn the basic architecture of an XIP™ Application and how it interacts with the XIP Host™ and with the GUI system. 2) Become familiar with the capabilities available in the XIP Libraries™. 3) Describe how to use the XIP Builder™ and GUI engine to create XIP Applications from modules in the XIP Libraries. 4) Understand the c...

Spatial relationships are conveyed in three-dimensional ultrasound imaging. To transition a volume rendering from one view to another view, the transition is animated, showing rotation. For example, the user examines one diagnostic view, but decides to examine another diagnostic view. Upon selection of the other diagnostic view, the volume rendered...

Adaptive volume rendering is provided for medical diagnostic ultrasound. The opacity of B-mode data is set relative to the opacity of Doppler data. The opacities for the different types of data are set as a function of ray depth. For example, the opacity of B-mode data near a tissue border is set to be more opaque than for tissue away from the bord...

Lundström C, Persson A, Ross S, Ljung P, Lindholm S, Gyllensvärd F, Ynnerman A. State-of-the-art of visualization in post-mortem imaging. APMIS 2012; 120: 316–26. Autopsies constitute a valuable feedback to the healthcare chain to achieve improvements in quality of care and cost effectiveness. This review describes post-mortem imaging, which has em...

We present an algorithm that enables real-time dynamic shading in direct volume rendering using general lighting, including directional lights, point lights, and environment maps. Real-time performance is achieved by encoding local and global volumetric visibility using spherical harmonic (SH) basis functions stored in an efficient multiresolution...

In many applications of Direct Volume Rendering (DVR) the importance of a certain material or feature is highly dependent on its relative spatial location. For instance, in the medical diagnostic procedure, the patient's symptoms often lead to specification of features, tissues and organs of particular interest. One such example is pockets of gas w...

This paper presents a novel technique to efficiently compute illumination for Direct Volume Rendering using a local approximation of ambient occlusion to integrate the intensity of incident light for each voxel. An advantage with this local approach is that fully shadowed regions are avoided, a desirable feature in many applications of volume rende...

We present a novel approach to interactive and concurrent volume visualization of functional Magnetic Resonance Imaging (fMRI). While the patient is in the scanner, data is extracted in real-time using state-of-the-art signal processing techniques. The fMRI signal is treated as light emission when rendering a patient-specific high resolution refere...

Virtual Colonoscopy is an important procedure for screening and detecting colorectal cancer. It increases patient comfort and reduces risks compared to optical colonoscopy. Oral contrast is used to emphasize the soft tissue border and avoid the need for physical colon cleansing. In order to ensure a reliable diagnosis, it is currently necessary to...

A single digital pathology image can occupy over 10 gigabytes of hard disk space, rendering it difficult to store, analyze, and transmit. Though image compression provides a means of reducing the storage requirement, its effects on CAD (and pathologist) performance are not yet clear. In this work we assess the impact of compression on the ability o...

There are numerous advantages described of how imaging technology can support forensic examinations. However, postmortem examinations of bodies are mainly performed to address demands which differ from those of traditional clinical image processing. This needs to be kept in mind when gathering information from image data sets for forensic purposes....

Multiple-volume visualization is a growing field in medical imaging providing simultaneous exploration of volumes acquired from varying modalities. However, high complexity results in an increased strain on performance compared to single volume rendering as scenes may consist of volumes with arbitrary orientations and rendering is performed with va...

We explore preliminary a 3D wave cavity in which the interior complex wave functions are of Berry‐type. Streamlines and novel disc‐like features are uncovered by means of selective and interactive visualization.

Volume raycasting techniques are important for both visual arts and visualization. They allow efficient generation of visual effects and visualization of scientific data obtained by tomography or numerical simulation. Volume-rendering techniques are also effective for direct rendering of implicit surfaces used for soft-body animation and constructi...

A novel technique for efficient computation of global light propagation in interactive DVR is presented in this paper. The approach is based on a combination of local shadows from the vicinity of each voxel with global shadows calculated at high resolution but stored in a sparser grid. The resulting intensities are then used as the initial illumina...

We propose a framework which allows an application developer to construct and execute pipelines of existing CUDA kernel programs without programming the somewhat complex kernel configuration and setup. The framework is a new addition to the eXtensible Imaging Platform (XIP) of the National Cancer Institute. Pipeline construction is carried out thro...

Volume raycasting techniques are important for both visual arts and visualization. They allow an efficient generation of visual effects and the visualization of scientific data obtained by tomography or numerical simulation. Thanks to their flexibility, experts agree that GPU-based raycasting is the state-of-the art technique for interactive volume...

Direct volume rendering (DVR) techniques is one of the important supporting technologies of virtual autopsy (VA. DVR render the images by sampling the volume data directly and may capture tissue thickness and densities in addition to surfaces. A VA procedure starts with a CT scan and then followed by a collaborative DVR session for visual analysis...

Direct volume rendering has proved to be an effective visualization method for medical data sets and has reached wide-spread clinical use. The diagnostic exploration, in essence, corresponds to a tissue classification task, which is often complex and time-consuming. Moreover, a major problem is the lack of information on the uncertainty of the clas...

This paper introduces a novel technique to compute illumination for Direct Volume Rendering. By adding shadow effects to volume rendered images, the perception of shapes and tissue properties can be significantly improved and it has the potential to increase the diagnostic value of medical volume rendering. The integrated intensity of incident ligh...

This paper introduces Temporal Density Parallel Coordinates (TDPC) and Depth Cue Parallel Coordinates (DCPC) which extend the standard 2D parallel coordinates technique to capture time-varying dynamics. The pro- posed techniques can be used to analyse temporal positions of data items as well as temporal positions of changes occurring using 2D displ...

Direct Volume Rendering (DVR) is of increasing diagnostic value in the analysis of data sets captured using the latest medical imaging modalities. The deployment of DVR in everyday clinical work, however, has so far been limited. One contributing factor is that current Transfer Function (TF) models can encode only a small fraction of the user's dom...

This paper presents a procedure for virtual autopsies based on interactive 3D visualizations of large scale, high resolution data from CT-scans of human cadavers. The procedure is described using examples from forensic medicine and the added value and future potential of virtual autopsies is shown from a medical and forensic perspective. Based on t...

Multi-dimensional Transfer Functions (MDTFs) are increasingly used in volume rendering to produce high quality visualizations of complex data sets. A major factor limiting the use of MDTFs is that the available design tools have not been simple enough to reach wide usage outside of the research context, for instance in clinical medical imaging. In...

Parallel coordinates is a well-known technique used for visualization of multivariate data. When the size of the data sets increases the parallel coordinates display results in an image far too cluttered to perceive any structure. We tackle this problem by constructing high-precision textures to represent the data. By using transfer functions that...

The high complexity of Transfer Function (TF) design is a major obstacle to widespread routine use of Direct Volume Rendering, particularly in the case of medical imaging. Both manual and automatic TF design schemes would benefit greatly from a fast and simple method for detection of tissue value ranges. To this end, we introduce the a-histogram, a...

We present a direct interblock interpolation technique that enables direct volume rendering of blocked, multireso- lution volumes. The proposed method smoothly interpolates between blocks of arbitrary block-wise level-of-detail (LOD) without sample replication or padding. This permits extreme changes in resolution across block boundaries and remove...

This paper presents a novel direct volume rendering technique for adaptive object-and image-space sampling density of multiresolution volumes. The raycasting is implemented entirely on the GPU in a single pass fragment program which adapts the sampling density along rays, guided by block resolutions. The multiresolution volumes are provided by a tr...

In order to gain insight into multivariate data, complex structures must be analysed and understood. Parallel coordinates is an excellent tool for visualizing this type of data but has its limitations. This paper deals with one of its main limitations - how to visualize a large number of data items without hiding the inherent structure they constit...

Direct Volume Rendering (DVR) is known to be of diagnostic value in the analysis of medical data sets. However, its deployment in everyday clinical use has so far been limited. Two major challenges are that the current methods for Transfer Function (TF) construction are too complex and that the tissue separation abilities of the TF need to be exten...

The size of standard volumetric data sets in medical imaging is rapidly increasing causing severe performance limitations in direct volume rendering pipelines. The methods presented in this paper exploit the medical knowledge embedded in the transfer function to reduce the required bandwidth in the pipeline. Typically, medical transfer functions ca...

We propose an interactive visualization approach to finding a mathematical model for a real world process, commonly known in the field of control theory as system identification. The use of interactive visualization techniques provides the modeller with instant visual feedback which facilitates the model validation process. When working interactive...

Visual analysis of time varying scientific data can be divided into four different categories with an increasing degree of user interaction. 1) Production of static images representing scientific data at selected times. 2) Production of video sequences in which graphical representation, time line and viewpoints are predefined. 3) Interactive stream...

Regular and stochastic behavior in single particle orbits in static magnetic reversals have wide application in laboratory and physical plasmas. In a simple magnetic reversal, the system has three degrees of freedom but only two global (exact) constants of the motion; the system is nonintegrable and the particle motion can, under certain conditions...

We examine wave-particle interactions in a magnetized plasma. We present snapshots of an animation of the three-dimensional electron phase space distribution produced by an electrostatic wave propagating across a magnetic field. The distribution function has been evolved by a particle in cell simulation. The electron phase space has been visualized...

Observations of synchrotron radiation across a wide range of wavelengths provide clear evidence that cosmic ray electrons are accelerated to relativistic energies in supernova remnants (SNRs). It is widely accepted that these observations can be interpreted in terms of diffusive shock acceleration. However, the search for a viable mechanism for pre...

Collisionless quasiperpendicular shocks with magnetoacoustic Mach numbers exceeding a certain threshold are known to reflect a fraction of the upstream ion population. These reflected ions drive instabilities which, in a magnetized plasma, can give rise to electron acceleration. In the case of shocks associated with supernova remnants (SNRs), elect...

In this work we present a visualization system for interactive real- time animation and visualization of simulation results from a par- allel Particle-In-Cell code. The system was designed and imple- mented for the Onyx2 InifiniteReality hardware. A number of dif- ferent visual objects, such as volume rendered particle density func- tionals were im...

This paper presents new methods for efficient extraction of intersec- tion curves between iso-surfaces of any pair of co-located 3D scalar fields. The first method is based on the Marching Cubes algorithm which has been enhanced to produce an additional data structure that makes it possible to reduce the complexity of the general sur- face intersec...

Visualization methods such as Direct Volume Rendering (DVR) have been suc-cessfully applied to many domains, above all medical imaging. The Transfer Func-tion (TF) is a central concept in DVR and has been used for high-quality, efficient rendering schemes. There are, however, much further potential to exploit both in terms of improved information c...