Mario Sousa - Academia.edu (original) (raw)

Papers by Mario Sousa

Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to pl... more Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to place feature curves (red stroke) on the surface of the mesh (left); The adaptive mesh refinement stage increases the mesh resolution around the features (middle); Finally, the feature creation displaces vertices to create a surficial feature (right).

Constructing or refining complex reservoir models at the appraisal, development, or production st... more Constructing or refining complex reservoir models at the appraisal, development, or production stage is a challenging and time-consuming task that entails a high degree of uncertainty. The challenge is significantly increased by the lack of modeling, simulation and visualization tools that allow prototyping of reservoir models and development concepts, and which are simple and intuitive to use. Conventional modeling workflows, facilitated by commercially available software packages, have remained essentially unchanged for the past decade. However, these are slow, often requiring many months from initial model concepts to flow simulation or other outputs; moreover, many model concepts, such as large scale reservoir architecture, become fixed early in the process and are difficult to retrospectively change. Such workflows are poorly suited to rapid prototyping of a range of reservoir model concepts, well trajectories and development options, and testing of how these might impact on reservoir behavior. We present a new reservoir modeling and simulation approach termed Rapid Reservoir Modeling (RRM) that allows such prototyping and complements existing workflows. In RRM, reservoir geometries that describe geologic heterogeneities (e.g. faults, stratigraphic, sedimentologic and/or diagenetic features) are modelled as discrete volumes bounded by surfaces, without reference to a predefined grid. These surfaces, and also well trajectories, are created and modified using intuitive, interactive techniques from computer visualization, such as Sketch Based Interfaces and Modeling (SBIM). Input data can be sourced from seismic, geocellular or flow simulation models, outcrop analogues, conceptual model libraries or blank screen. RRM outputs can be exported to conventional workflows at any stage. Gridding or meshing of the models within the RRM framework allows rapid calculation of key reservoir properties and dynamic behaviors linked with well trajectories and development plans. We demonstrate here a prototype of the RRM workflow using a number of examples. The work is significant because it allows, for the first time, application of rapid prototyping methods in reservoir modeling and simulation. Such methods are widely used in other fields of engineering design and allow improved scoping of concepts and options prior, or in addition, to detailed modeling. Moreover, SBIM can be used on a range of hardware architectures, including table tops and surface PCs, fostering collaboration within integrated asset teams.

Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to righ... more Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to right, sketched geologic map, generated 3D model, and exploded view of the model.

Computers & Graphics, May 1, 2015

Multidimensional projection has become a standard tool for visual analysis of multidimensional da... more Multidimensional projection has become a standard tool for visual analysis of multidimensional data sets, as the 2D representation of multidimensional instances gives an important and informative panorama of the data. Recently, research in this torojection, a recently proposed resampling mechanism that allows users to generate new multidimensional instances by creating reference 2D points in the projection space. Given an m-dimensional data set and its 2D projection, inverse projection transforms a user-defined 2D point into an m-dimensional point by means of a mapping function. In this work, we propose a novel inverse projection technique based on Radial Basis Functions interpolation. Our technique provides a smooth and global mapping from low to high dimensions, in contrast with the former technique (iLAMP) which is local and piecewise continuous. In order to demonstrate the potential of our technique, we use a 3D human-faces data set and a procedure to interactively reconstruct and generate new 3D faces. The results demonstrate the simplicity, robustness and efficiency of our approach to create new face models from a structured data set, a task that would typically require the manipulation of hundreds of parameters.

Traditional user interfaces in modeling have followed the WIMP (Window, Icon, Menu, Pointer) para... more Traditional user interfaces in modeling have followed the WIMP (Window, Icon, Menu, Pointer) paradigm. While functional and powerful, they can also be cumbersome and daunting to a novice user; creating a complex model requires much expertise and effort. A recent trend is toward more accessible and natural interfaces, which has lead to sketch-based interfaces for modeling (SBIM). The goal is to allow hand-drawn sketches to be used in the modeling process, from rough model creation through to fine detail construction. Mapping 2D sketches to a 3D modeling operation is a difficult and ambiguous task, so our categorization is based on how an SBIM application chooses to interpret a sketch, of which there are three primary methods: to create a 3D model, to add details to an existing model, or to deform and manipulate a model. In this STAR, we present a taxonomy of sketchbased interfaces focused on geometric modeling applications. The canonical and recent works are presented and classified,...

Computers & Graphics, 2015

We present two sketch-based modeling systems built using adaptive meshes and editing operators. T... more We present two sketch-based modeling systems built using adaptive meshes and editing operators. The first one has the capability to control local and global changes to the model; the second one follows geological domain constraints. To build a system that provides the user with control of local modifications we developed a mathematical theory of vertex label and atlas structure for adaptive meshes based on stellar operators. We also take a more theoretical approach to the problem of sketch-based surface modeling (SBSM) and introduce a framework for SBSM systems based on adaptive meshes. The main advantage of this approach is a clear separation between the modeling operators and the final representation, thus enabling the creation of SBSM systems suited to specific domains with different demands.

ECMOR XIII - 13th European Conference on the Mathematics of Oil Recovery, 2012

The development of unconventional reservoirs has received tremendous attention from energy compan... more The development of unconventional reservoirs has received tremendous attention from energy companies in recent years. Due to the low permeability nature of these resources, a hydraulic fracturing is often applied to stimulate the near-well region to enable economic production. The injection pressure, as it propagates, creates fractures that generate microseismic events. The monitoring of such events has become an important tool to better understand hydraulic fracture geometry, to estimate stimulated reservoir volume, to refine fracture treatment, and to optimize long-term field development. In the estimation of Stimulated Reservoir Volume (SRV) from microseismic data, recent literature highlights the importance of using time and uncertainty to achieve a more accurate estimation, as well as the influence of more complex geometries in understanding the microseismic event cloud. However, the current methods do not take any of these factors into consideration. In this work, we propose two different approaches to estimate the SRV that integrate spatial correlation together with time to obtain more accurate volume estimations. The first method is called alpha-shapes which is a generalization of the well-known shrink-wrap algorithm. The second approach is the densitybased region reconstruction which considers the density of the microseismic samples in the space to reconstruct the SRV. The density-based approach uses radial basis function with Gaussian kernels to account for uncertainty in microseismic events. In addition to these two methods, we also developed a sketch-based tool to assist the users in filtering microseismic events that are visibly wrong. We molded these two approaches to allow for direct user changes to the final volume through sketch-based tools, and thus giving the expert the ability to guide the SRV estimation and to create "what-if" scenarios for a better understanding of the microseismic data. We also integrated the developed tools in this work with an interactive tabletop multitouch display to create a collaborative work environment for the experts.

Computers & Graphics, 2015

Multidimensional projection has become a standard tool for visual analysis of multidimensional da... more Multidimensional projection has become a standard tool for visual analysis of multidimensional data sets, as the 2D representation of multidimensional instances gives an important and informative panorama of the data. Recently, research in this torojection, a recently proposed resampling mechanism that allows users to generate new multidimensional instances by creating reference 2D points in the projection space. Given an m-dimensional data set and its 2D projection, inverse projection transforms a user-defined 2D point into an m-dimensional point by means of a mapping function. In this work, we propose a novel inverse projection technique based on Radial Basis Functions interpolation. Our technique provides a smooth and global mapping from low to high dimensions, in contrast with the former technique (iLAMP) which is local and piecewise continuous. In order to demonstrate the potential of our technique, we use a 3D human-faces data set and a procedure to interactively reconstruct and generate new 3D faces. The results demonstrate the simplicity, robustness and efficiency of our approach to create new face models from a structured data set, a task that would typically require the manipulation of hundreds of parameters.

Proceedings of the 4th Joint Symposium on Computational Aesthetics, Non-Photorealistic Animation and Rendering, and Sketch-Based Interfaces and Modeling, 2014

Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to righ... more Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to right, sketched geologic map, generated 3D model, and exploded view of the model.

CHI '13 Extended Abstracts on Human Factors in Computing Systems, 2013

Microseismic visualization systems present complex 3D data of small seismic events within oil res... more Microseismic visualization systems present complex 3D data of small seismic events within oil reservoirs to allow experts to explore and interact with that data. Yet existing systems suffer several problems: 3D spatial navigation and orientation is difficult, and selecting 3D data is challenging due to the problems of occlusion and lack of depth perception. Our work mitigates these problems by applying both proxemic interactions and a spatial input device to simplify how experts navigate through the visualization, and a painting metaphor to simplify how they select that information.

2011 24th SIBGRAPI Conference on Graphics, Patterns and Images, 2011

Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to pl... more Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to place feature curves (red stroke) on the surface of the mesh (left); The adaptive mesh refinement stage increases the mesh resolution around the features (middle); Finally, the feature creation displaces vertices to create a surficial feature (right).

ACM SIGGRAPH 2006 Courses on - SIGGRAPH '06, 2006

Various systems have explored the idea of inferring 3D models from sketched 2D outlines. In all o... more Various systems have explored the idea of inferring 3D models from sketched 2D outlines. In all of these systems the underlying modeling methodology limits the complexity of models that can be created interactively. The ShapeShop sketch-based modeling system utilizes Hierarchical Implicit Volume Models (BlobTrees) as an underlying shape representation. The BlobTree framework supports interactive creation of complex, detailed solid models with arbitrary topology. A new technique is described for inflating 2D contours into rounded three-dimensional implicit volumes. Sketch-based modeling operations are defined that combine these basic shapes using standard blending and CSG operators. Since the underlying volume hierarchy is by definition a construction history, individual sketched components can be non-linearly edited and removed. For example, holes can be interactively dragged through a shape. ShapeShop also provides 2D drawing assistance using a new curve-sketching system based on variational contours. A wide range of models can be sketched with ShapeShop, from cartoon-like characters to detailed mechanical parts. Examples are shown which demonstrate significantly higher model complexity than existing systems.

2014 27th SIBGRAPI Conference on Graphics, Patterns and Images, 2014

In the last 15 years many systems for sketch-based modeling have been developed. Much of this wor... more In the last 15 years many systems for sketch-based modeling have been developed. Much of this work has focused on the final results and describes the solutions from a technical and practical point of view. In this paper we take a more theoretical approach to the problem of sketch-based surface modeling (SBSM) and introduce a framework for SBSM systems based on adaptive meshes. The main advantage of this approach is to split the modeling operators and the final representation, allowing the creation of SBSM systems suitable for specific domains with different demands. In addition, we present two systems built on top of this framework, one with the capability to control local and global changes to the model and one that follows domain constraints.

Proceedings of the 8th International Symposium on Non-Photorealistic Animation and Rendering - NPAR 10, 2010

Figure 1: Drawing steps of David's head with our system. (a) Given a set of point and normal samp... more Figure 1: Drawing steps of David's head with our system. (a) Given a set of point and normal samples, a Hermite Radial Basis Function is reconstructed and directly rendered, depicting shape and tone in different styles: (b) silhouettes with hidden-line attenuation; (c) adding a small number of stippling marks; (d) increasing number of stippling marks and adding curvature-based cross hatching, and (e) completing the tone depiction by adding more stippling marks and enhancing interior contours with a white halo. The model has 4096 samples, 700K render points and with CPU rendering at 16 fps.

We present techniques for modeling Variational Hermite Radial Basis Function (VHRBF) Implicits us... more We present techniques for modeling Variational Hermite Radial Basis Function (VHRBF) Implicits using a set of sketch-based interface and modeling (SBIM) operators. VHRBF Implicits is a simple and compact representation well suited for SBIM. It provides quality reconstructions, preserving the intended shape from a coarse and nonuniform number of point-normal samples extracted directly from the input strokes. In addition, it has a number of desirable properties such as parameter-free modeling, invariance under geometric similarities on the input strokes, suitable estimation of differential quantities, good behavior near close sheets, and both linear fitting and reproduction. Our approach uses these properties of VHRBF Implicits to quickly and robustly generate the overall shape of 3D models. We present examples of implicit models obtained from a set of SBIM language operators for contouring, cross-editing, kneading, oversketching and merging.

Computers & Graphics, 2011

We present techniques for rendering implicit surfaces in different pen-and-ink styles. The implic... more We present techniques for rendering implicit surfaces in different pen-and-ink styles. The implicit models are rendered using point-based primitives to depict shape and tone using silhouettes with hidden-line attenuation, drawing directions, and stippling. We present sample renderings obtained for a variety of models. Furthermore, we describe simple and novel methods to control point placement and rendering style. Our approach is implemented using HRBF Implicits, a simple and compact representation, that has three fundamental qualities: a small number of point-normal samples as input for surface reconstruction, good projection of points near the surface, and smoothness of the gradient field. These qualities of HRBF Implicits are used to generate a robust distribution of points to position the drawing primitives.

ABSTRACT Constructing structurally complex reservoir models at the appraisal stage is a complex t... more ABSTRACT Constructing structurally complex reservoir models at the appraisal stage is a complex task, with a high-degree of uncertainty. The lack of an intuitive set of modeling and visualization tools that support expert visual interpretation from geophysicists and geologists significantly increases the challenge. We present a set of interactive software tools to reservoir modeling in the appraisal stage. Our project use sketch-based modeling tools to allow the users to guide the model process with his/her expertise intuitively and quickly. We propose two different approaches that depend on the input data. The first approach is to create "what if" scenarios and start with no data or sparse data. The second one is to edit horizons which will form the horizon and fault network, and start using the seismic volume and a pre-extracted horizon.

Graphical Models, 2011

While current image deformation methods are careful in making the new geometry seem right, little... more While current image deformation methods are careful in making the new geometry seem right, little attention has been given to the photometric aspects. We introduce a deformation method that results in coherently illuminated objects. For this task, we use RGBN images to support a relighting step integrated in a sketch-based deformation method. We warp not only colors but also normals. Normal warping requires smooth warping fields. We use sketches to specify sparse warping samples and impose additional constraints for region of interest control. To satisfy these new constraints, we present a novel image warping method based on Hermite-Birkhoff interpolation with radial basis functions that results in a smooth warping field. We also use sketches to help the system identify both lighting conditions and material from single images. We present results with RGBN images from different sources, including photometric stereo, synthetic images, and photographs.

pages.cpsc.ucalgary.ca, May 29, 2009

We present an implicit modeling system as a tool for the creation of a wide range of aesthetic mo... more We present an implicit modeling system as a tool for the creation of a wide range of aesthetic models. Because of their ability to form blends and produce both organic shapes as well as man made objects, implicit surfaces are a good medium for artists seeking new ...

Petroleum reservoir model building is a fundamental but complex task present in all stages of oil... more Petroleum reservoir model building is a fundamental but complex task present in all stages of oil/gas exploration and production (E&P). Reservoir models are built incrementally using multi-disciplinary data (e.g. from geophysics, geology, reservoir engineering) and the domain expert interpretation of that data. The first reservoir models are constructed at the appraisal stage, where the available data presents inaccuracies and a

Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to pl... more Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to place feature curves (red stroke) on the surface of the mesh (left); The adaptive mesh refinement stage increases the mesh resolution around the features (middle); Finally, the feature creation displaces vertices to create a surficial feature (right).

Constructing or refining complex reservoir models at the appraisal, development, or production st... more Constructing or refining complex reservoir models at the appraisal, development, or production stage is a challenging and time-consuming task that entails a high degree of uncertainty. The challenge is significantly increased by the lack of modeling, simulation and visualization tools that allow prototyping of reservoir models and development concepts, and which are simple and intuitive to use. Conventional modeling workflows, facilitated by commercially available software packages, have remained essentially unchanged for the past decade. However, these are slow, often requiring many months from initial model concepts to flow simulation or other outputs; moreover, many model concepts, such as large scale reservoir architecture, become fixed early in the process and are difficult to retrospectively change. Such workflows are poorly suited to rapid prototyping of a range of reservoir model concepts, well trajectories and development options, and testing of how these might impact on reservoir behavior. We present a new reservoir modeling and simulation approach termed Rapid Reservoir Modeling (RRM) that allows such prototyping and complements existing workflows. In RRM, reservoir geometries that describe geologic heterogeneities (e.g. faults, stratigraphic, sedimentologic and/or diagenetic features) are modelled as discrete volumes bounded by surfaces, without reference to a predefined grid. These surfaces, and also well trajectories, are created and modified using intuitive, interactive techniques from computer visualization, such as Sketch Based Interfaces and Modeling (SBIM). Input data can be sourced from seismic, geocellular or flow simulation models, outcrop analogues, conceptual model libraries or blank screen. RRM outputs can be exported to conventional workflows at any stage. Gridding or meshing of the models within the RRM framework allows rapid calculation of key reservoir properties and dynamic behaviors linked with well trajectories and development plans. We demonstrate here a prototype of the RRM workflow using a number of examples. The work is significant because it allows, for the first time, application of rapid prototyping methods in reservoir modeling and simulation. Such methods are widely used in other fields of engineering design and allow improved scoping of concepts and options prior, or in addition, to detailed modeling. Moreover, SBIM can be used on a range of hardware architectures, including table tops and surface PCs, fostering collaboration within integrated asset teams.

Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to righ... more Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to right, sketched geologic map, generated 3D model, and exploded view of the model.

Computers & Graphics, May 1, 2015

Multidimensional projection has become a standard tool for visual analysis of multidimensional da... more Multidimensional projection has become a standard tool for visual analysis of multidimensional data sets, as the 2D representation of multidimensional instances gives an important and informative panorama of the data. Recently, research in this torojection, a recently proposed resampling mechanism that allows users to generate new multidimensional instances by creating reference 2D points in the projection space. Given an m-dimensional data set and its 2D projection, inverse projection transforms a user-defined 2D point into an m-dimensional point by means of a mapping function. In this work, we propose a novel inverse projection technique based on Radial Basis Functions interpolation. Our technique provides a smooth and global mapping from low to high dimensions, in contrast with the former technique (iLAMP) which is local and piecewise continuous. In order to demonstrate the potential of our technique, we use a 3D human-faces data set and a procedure to interactively reconstruct and generate new 3D faces. The results demonstrate the simplicity, robustness and efficiency of our approach to create new face models from a structured data set, a task that would typically require the manipulation of hundreds of parameters.

Traditional user interfaces in modeling have followed the WIMP (Window, Icon, Menu, Pointer) para... more Traditional user interfaces in modeling have followed the WIMP (Window, Icon, Menu, Pointer) paradigm. While functional and powerful, they can also be cumbersome and daunting to a novice user; creating a complex model requires much expertise and effort. A recent trend is toward more accessible and natural interfaces, which has lead to sketch-based interfaces for modeling (SBIM). The goal is to allow hand-drawn sketches to be used in the modeling process, from rough model creation through to fine detail construction. Mapping 2D sketches to a 3D modeling operation is a difficult and ambiguous task, so our categorization is based on how an SBIM application chooses to interpret a sketch, of which there are three primary methods: to create a 3D model, to add details to an existing model, or to deform and manipulate a model. In this STAR, we present a taxonomy of sketchbased interfaces focused on geometric modeling applications. The canonical and recent works are presented and classified,...

Computers & Graphics, 2015

We present two sketch-based modeling systems built using adaptive meshes and editing operators. T... more We present two sketch-based modeling systems built using adaptive meshes and editing operators. The first one has the capability to control local and global changes to the model; the second one follows geological domain constraints. To build a system that provides the user with control of local modifications we developed a mathematical theory of vertex label and atlas structure for adaptive meshes based on stellar operators. We also take a more theoretical approach to the problem of sketch-based surface modeling (SBSM) and introduce a framework for SBSM systems based on adaptive meshes. The main advantage of this approach is a clear separation between the modeling operators and the final representation, thus enabling the creation of SBSM systems suited to specific domains with different demands.

ECMOR XIII - 13th European Conference on the Mathematics of Oil Recovery, 2012

The development of unconventional reservoirs has received tremendous attention from energy compan... more The development of unconventional reservoirs has received tremendous attention from energy companies in recent years. Due to the low permeability nature of these resources, a hydraulic fracturing is often applied to stimulate the near-well region to enable economic production. The injection pressure, as it propagates, creates fractures that generate microseismic events. The monitoring of such events has become an important tool to better understand hydraulic fracture geometry, to estimate stimulated reservoir volume, to refine fracture treatment, and to optimize long-term field development. In the estimation of Stimulated Reservoir Volume (SRV) from microseismic data, recent literature highlights the importance of using time and uncertainty to achieve a more accurate estimation, as well as the influence of more complex geometries in understanding the microseismic event cloud. However, the current methods do not take any of these factors into consideration. In this work, we propose two different approaches to estimate the SRV that integrate spatial correlation together with time to obtain more accurate volume estimations. The first method is called alpha-shapes which is a generalization of the well-known shrink-wrap algorithm. The second approach is the densitybased region reconstruction which considers the density of the microseismic samples in the space to reconstruct the SRV. The density-based approach uses radial basis function with Gaussian kernels to account for uncertainty in microseismic events. In addition to these two methods, we also developed a sketch-based tool to assist the users in filtering microseismic events that are visibly wrong. We molded these two approaches to allow for direct user changes to the final volume through sketch-based tools, and thus giving the expert the ability to guide the SRV estimation and to create "what-if" scenarios for a better understanding of the microseismic data. We also integrated the developed tools in this work with an interactive tabletop multitouch display to create a collaborative work environment for the experts.

Computers & Graphics, 2015

Multidimensional projection has become a standard tool for visual analysis of multidimensional da... more Multidimensional projection has become a standard tool for visual analysis of multidimensional data sets, as the 2D representation of multidimensional instances gives an important and informative panorama of the data. Recently, research in this torojection, a recently proposed resampling mechanism that allows users to generate new multidimensional instances by creating reference 2D points in the projection space. Given an m-dimensional data set and its 2D projection, inverse projection transforms a user-defined 2D point into an m-dimensional point by means of a mapping function. In this work, we propose a novel inverse projection technique based on Radial Basis Functions interpolation. Our technique provides a smooth and global mapping from low to high dimensions, in contrast with the former technique (iLAMP) which is local and piecewise continuous. In order to demonstrate the potential of our technique, we use a 3D human-faces data set and a procedure to interactively reconstruct and generate new 3D faces. The results demonstrate the simplicity, robustness and efficiency of our approach to create new face models from a structured data set, a task that would typically require the manipulation of hundreds of parameters.

Proceedings of the 4th Joint Symposium on Computational Aesthetics, Non-Photorealistic Animation and Rendering, and Sketch-Based Interfaces and Modeling, 2014

Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to righ... more Figure 1: Interpreting a sketched geologic map to generate a 3D geologic model. From left to right, sketched geologic map, generated 3D model, and exploded view of the model.

CHI '13 Extended Abstracts on Human Factors in Computing Systems, 2013

Microseismic visualization systems present complex 3D data of small seismic events within oil res... more Microseismic visualization systems present complex 3D data of small seismic events within oil reservoirs to allow experts to explore and interact with that data. Yet existing systems suffer several problems: 3D spatial navigation and orientation is difficult, and selecting 3D data is challenging due to the problems of occlusion and lack of depth perception. Our work mitigates these problems by applying both proxemic interactions and a spatial input device to simplify how experts navigate through the visualization, and a painting metaphor to simplify how they select that information.

2011 24th SIBGRAPI Conference on Graphics, Patterns and Images, 2011

Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to pl... more Fig. 1. Overview of our modeling framework: The sketching stage allows the graphic designer to place feature curves (red stroke) on the surface of the mesh (left); The adaptive mesh refinement stage increases the mesh resolution around the features (middle); Finally, the feature creation displaces vertices to create a surficial feature (right).

ACM SIGGRAPH 2006 Courses on - SIGGRAPH '06, 2006

Various systems have explored the idea of inferring 3D models from sketched 2D outlines. In all o... more Various systems have explored the idea of inferring 3D models from sketched 2D outlines. In all of these systems the underlying modeling methodology limits the complexity of models that can be created interactively. The ShapeShop sketch-based modeling system utilizes Hierarchical Implicit Volume Models (BlobTrees) as an underlying shape representation. The BlobTree framework supports interactive creation of complex, detailed solid models with arbitrary topology. A new technique is described for inflating 2D contours into rounded three-dimensional implicit volumes. Sketch-based modeling operations are defined that combine these basic shapes using standard blending and CSG operators. Since the underlying volume hierarchy is by definition a construction history, individual sketched components can be non-linearly edited and removed. For example, holes can be interactively dragged through a shape. ShapeShop also provides 2D drawing assistance using a new curve-sketching system based on variational contours. A wide range of models can be sketched with ShapeShop, from cartoon-like characters to detailed mechanical parts. Examples are shown which demonstrate significantly higher model complexity than existing systems.

2014 27th SIBGRAPI Conference on Graphics, Patterns and Images, 2014

In the last 15 years many systems for sketch-based modeling have been developed. Much of this wor... more In the last 15 years many systems for sketch-based modeling have been developed. Much of this work has focused on the final results and describes the solutions from a technical and practical point of view. In this paper we take a more theoretical approach to the problem of sketch-based surface modeling (SBSM) and introduce a framework for SBSM systems based on adaptive meshes. The main advantage of this approach is to split the modeling operators and the final representation, allowing the creation of SBSM systems suitable for specific domains with different demands. In addition, we present two systems built on top of this framework, one with the capability to control local and global changes to the model and one that follows domain constraints.

Proceedings of the 8th International Symposium on Non-Photorealistic Animation and Rendering - NPAR 10, 2010

Figure 1: Drawing steps of David's head with our system. (a) Given a set of point and normal samp... more Figure 1: Drawing steps of David's head with our system. (a) Given a set of point and normal samples, a Hermite Radial Basis Function is reconstructed and directly rendered, depicting shape and tone in different styles: (b) silhouettes with hidden-line attenuation; (c) adding a small number of stippling marks; (d) increasing number of stippling marks and adding curvature-based cross hatching, and (e) completing the tone depiction by adding more stippling marks and enhancing interior contours with a white halo. The model has 4096 samples, 700K render points and with CPU rendering at 16 fps.

We present techniques for modeling Variational Hermite Radial Basis Function (VHRBF) Implicits us... more We present techniques for modeling Variational Hermite Radial Basis Function (VHRBF) Implicits using a set of sketch-based interface and modeling (SBIM) operators. VHRBF Implicits is a simple and compact representation well suited for SBIM. It provides quality reconstructions, preserving the intended shape from a coarse and nonuniform number of point-normal samples extracted directly from the input strokes. In addition, it has a number of desirable properties such as parameter-free modeling, invariance under geometric similarities on the input strokes, suitable estimation of differential quantities, good behavior near close sheets, and both linear fitting and reproduction. Our approach uses these properties of VHRBF Implicits to quickly and robustly generate the overall shape of 3D models. We present examples of implicit models obtained from a set of SBIM language operators for contouring, cross-editing, kneading, oversketching and merging.

Computers & Graphics, 2011

We present techniques for rendering implicit surfaces in different pen-and-ink styles. The implic... more We present techniques for rendering implicit surfaces in different pen-and-ink styles. The implicit models are rendered using point-based primitives to depict shape and tone using silhouettes with hidden-line attenuation, drawing directions, and stippling. We present sample renderings obtained for a variety of models. Furthermore, we describe simple and novel methods to control point placement and rendering style. Our approach is implemented using HRBF Implicits, a simple and compact representation, that has three fundamental qualities: a small number of point-normal samples as input for surface reconstruction, good projection of points near the surface, and smoothness of the gradient field. These qualities of HRBF Implicits are used to generate a robust distribution of points to position the drawing primitives.

ABSTRACT Constructing structurally complex reservoir models at the appraisal stage is a complex t... more ABSTRACT Constructing structurally complex reservoir models at the appraisal stage is a complex task, with a high-degree of uncertainty. The lack of an intuitive set of modeling and visualization tools that support expert visual interpretation from geophysicists and geologists significantly increases the challenge. We present a set of interactive software tools to reservoir modeling in the appraisal stage. Our project use sketch-based modeling tools to allow the users to guide the model process with his/her expertise intuitively and quickly. We propose two different approaches that depend on the input data. The first approach is to create "what if" scenarios and start with no data or sparse data. The second one is to edit horizons which will form the horizon and fault network, and start using the seismic volume and a pre-extracted horizon.

Graphical Models, 2011

While current image deformation methods are careful in making the new geometry seem right, little... more While current image deformation methods are careful in making the new geometry seem right, little attention has been given to the photometric aspects. We introduce a deformation method that results in coherently illuminated objects. For this task, we use RGBN images to support a relighting step integrated in a sketch-based deformation method. We warp not only colors but also normals. Normal warping requires smooth warping fields. We use sketches to specify sparse warping samples and impose additional constraints for region of interest control. To satisfy these new constraints, we present a novel image warping method based on Hermite-Birkhoff interpolation with radial basis functions that results in a smooth warping field. We also use sketches to help the system identify both lighting conditions and material from single images. We present results with RGBN images from different sources, including photometric stereo, synthetic images, and photographs.

pages.cpsc.ucalgary.ca, May 29, 2009

We present an implicit modeling system as a tool for the creation of a wide range of aesthetic mo... more We present an implicit modeling system as a tool for the creation of a wide range of aesthetic models. Because of their ability to form blends and produce both organic shapes as well as man made objects, implicit surfaces are a good medium for artists seeking new ...

Petroleum reservoir model building is a fundamental but complex task present in all stages of oil... more Petroleum reservoir model building is a fundamental but complex task present in all stages of oil/gas exploration and production (E&P). Reservoir models are built incrementally using multi-disciplinary data (e.g. from geophysics, geology, reservoir engineering) and the domain expert interpretation of that data. The first reservoir models are constructed at the appraisal stage, where the available data presents inaccuracies and a