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Realism
Kinds of Realism Selected AbstractsRORTY ON REALISM AND CONSTRUCTIVISMMETAPHILOSOPHY, Issue 3 2005James A. Stieb Abstract: This article argues that we can and should recognize the mind dependence, epistemic dependence, and social dependence of theories of mind-independent reality, as opposed to Rorty, who thinks not even a constructivist theory of mind-independent reality can be had. It accuses Rorty of creating an equivocation or "dualism of scheme and content" between causation and justification based on various "Davidsonian" irrelevancies, not to be confused with the actual Davidson. These include the Principle of Charity, the attack against conceptual schemes, the linguistification of social practice, intersubjectivism, and causal naturalism. It follows that realists and constructivists need neither follow Rorty's mischaracterizations nor succumb to his internal paradoxes. [source] GOD IN POSTLIBERAL PERSPECTIVE: BETWEEN REALISM AND NON-REALISMNEW BLACKFRIARS, Issue 1034 2010ANDREW MOORE No abstract is available for this article. [source] BEST EXPLANATION AND SCIENTIFIC REALISMPHILOSOPHICAL FORUM, Issue 2 2007YVONNE RALEY First page of article [source] INTENTIONAL REALISM AND MORAL REALISMPHILOSOPHICAL FORUM, Issue 2 2006STEVEN ROSS First page of article [source] TWO ARGUMENTS AGAINST REALISMTHE PHILOSOPHICAL QUARTERLY, Issue 231 2008Timothy Bays I present two generalizations of Putnam's model-theoretic argument against realism. The first replaces Putnam's model theory with some new, and substantially simpler, model theory, while the second replaces Putnam's model theory with some more accessible results from astronomy. By design, both of these new arguments fail. But the similarities between these new arguments and Putnam's original arguments illuminate the latter's overall structure, and the flaws in these new arguments highlight the corresponding flaws in Putnam's arguments. [source] REALISM AND THE BOUNDARIES OF GENRE IN DUTCH ARTART HISTORY, Issue 1 2009DAVID R. SMITH This essay examines the critical, though largely unrecognized, role of generic parody in Dutch art of the seventeenth century. These often subtle parodies point beyond prevailing definitions of realism as surface description to reveal the deeper ,surplus' of reality that lies beneath a given generic convention. As Bakhtin has shown, genres are inherently ideological and exemplary. By undermining their conventions, Dutch artists were also often undermining their accompanying didactic messages and moral norms. They thereby contribute to a multi-layered, frequently ambivalent, form of realism that is at the heart of what is most novel and most ,modern' in Dutch art. [source] Fast Inverse Reflector Design (FIRD)COMPUTER GRAPHICS FORUM, Issue 8 2009A. Mas I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling , Physically based modeling; I.3.1 [Hardware architecture]: Graphics processors Abstract This paper presents a new inverse reflector design method using a GPU-based computation of outgoing light distribution from reflectors. We propose a fast method to obtain the outgoing light distribution of a parametrized reflector, and then compare it with the desired illumination. The new method works completely in the GPU. We trace millions of rays using a hierarchical height-field representation of the reflector. Multiple reflections are taken into account. The parameters that define the reflector shape are optimized in an iterative procedure in order for the resulting light distribution to be as close as possible to the desired, user-provided one. We show that our method can calculate reflector lighting at least one order of magnitude faster than previous methods, even with millions of rays, complex geometries and light sources. [source] A Bayesian Monte Carlo Approach to Global IlluminationCOMPUTER GRAPHICS FORUM, Issue 8 2009Jonathan Brouillat I.3.7 [Computer Graphics]: Three-Dimensional Graphics an Realism Abstract Most Monte Carlo rendering algorithms rely on importance sampling to reduce the variance of estimates. Importance sampling is efficient when the proposal sample distribution is well-suited to the form of the integrand but fails otherwise. The main reason is that the sample location information is not exploited. All sample values are given the same importance regardless of their proximity to one another. Two samples falling in a similar location will have equal importance whereas they are likely to contain redundant information. The Bayesian approach we propose in this paper uses both the location and value of the data to infer an integral value based on a prior probabilistic model of the integrand. The Bayesian estimate depends only on the sample values and locations, and not how these samples have been chosen. We show how this theory can be applied to the final gathering problem and present results that clearly demonstrate the benefits of Bayesian Monte Carlo. [source] Replica Exchange Light TransportCOMPUTER GRAPHICS FORUM, Issue 8 2009Shinya Kitaoka I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; I.3.3 [Computer Graphics]: Picture/Image Generation Abstract We solve the light transport problem by introducing a novel unbiased Monte Carlo algorithm called replica exchange light transport, inspired by the replica exchange Monte Carlo method in the fields of computational physics and statistical information processing. The replica exchange Monte Carlo method is a sampling technique whose operation resembles simulated annealing in optimization algorithms using a set of sampling distributions. We apply it to the solution of light transport integration by extending the probability density function of an integrand of the integration to a set of distributions. That set of distributions is composed of combinations of the path densities of different path generation types: uniform distributions in the integral domain, explicit and implicit paths in light (particle/photon) tracing, indirect paths in bidirectional path tracing, explicit and implicit paths in path tracing, and implicit caustics paths seen through specular surfaces including the delta function in path tracing. The replica-exchange light transport algorithm generates a sequence of path samples from each distribution and samples the simultaneous distribution of those distributions as a stationary distribution by using the Markov chain Monte Carlo method. Then the algorithm combines the obtained path samples from each distribution using multiple importance sampling. We compare the images generated with our algorithm to those generated with bidirectional path tracing and Metropolis light transport based on the primary sample space. Our proposing algorithm has better convergence property than bidirectional path tracing and the Metropolis light transport, and it is easy to implement by extending the Metropolis light transport. [source] Animating Quadrupeds: Methods and ApplicationsCOMPUTER GRAPHICS FORUM, Issue 6 2009Ljiljana Skrba I.3.7 [Computer Graphics]: 3D Graphics and Realism , Animation Abstract Films like Shrek, Madagascar, The Chronicles of Narnia and Charlotte's web all have something in common: realistic quadruped animations. While the animation of animals has been popular for a long time, the technical challenges associated with creating highly realistic, computer generated creatures have been receiving increasing attention recently. The entertainment, education and medical industries have increased the demand for simulation of realistic animals in the computer graphics area. In order to achieve this, several challenges need to be overcome: gathering and processing data that embodies the natural motion of an animal , which is made more difficult by the fact that most animals cannot be easily motion-captured; building accurate kinematic models for animals, with adapted animation skeletons in particular; and developing either kinematic or physically-based animation methods, either by embedding some a priori knowledge about the way that quadrupeds locomote and/or adopting examples of real motion. In this paper, we present an overview of the common techniques used to date for realistic quadruped animation. This includes an outline of the various ways that realistic quadruped motion can be achieved, through video-based acquisition, physics based models, inverse kinematics or some combination of the above. [source] Compression of Human Motion Capture Data Using Motion Pattern IndexingCOMPUTER GRAPHICS FORUM, Issue 1 2009Qin Gu I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; E.4 [Coding and Information Theory]: Data Compaction and Compression Abstract In this work, a novel scheme is proposed to compress human motion capture data based on hierarchical structure construction and motion pattern indexing. For a given sequence of 3D motion capture data of human body, the 3D markers are first organized into a hierarchy where each node corresponds to a meaningful part of the human body. Then, the motion sequence corresponding to each body part is coded separately. Based on the observation that there is a high degree of spatial and temporal correlation among the 3D marker positions, we strive to identify motion patterns that form a database for each meaningful body part. Thereafter, a sequence of motion capture data can be efficiently represented as a series of motion pattern indices. As a result, higher compression ratio has been achieved when compared with the prior art, especially for long sequences of motion capture data with repetitive motion styles. Another distinction of this work is that it provides means for flexible and intuitive global and local distortion controls. [source] Transferring the Rig and Animations from a Character to Different Face ModelsCOMPUTER GRAPHICS FORUM, Issue 8 2008Verónica Costa Orvalho I.3.7 Computer Graphics: Three-Dimensional Graphics and Realism. Animation Abstract We introduce a facial deformation system that allows artists to define and customize a facial rig and later apply the same rig to different face models. The method uses a set of landmarks that define specific facial features and deforms the rig anthropometrically. We find the correspondence of the main attributes of a source rig, transfer them to different three-demensional (3D) face models and automatically generate a sophisticated facial rig. The method is general and can be used with any type of rig configuration. We show how the landmarks, combined with other deformation methods, can adapt different influence objects (NURBS surfaces, polygon surfaces, lattice) and skeletons from a source rig to individual face models, allowing high quality geometric or physically-based animations. We describe how it is possible to deform the source facial rig, apply the same deformation parameters to different face models and obtain unique expressions. We enable reusing of existing animation scripts and show how shapes nicely mix one with the other in different face models. We describe how our method can easily be integrated in an animation pipeline. We end with the results of tests done with major film and game companies to show the strength of our proposal. [source] Compression and Importance Sampling of Near-Field Light SourcesCOMPUTER GRAPHICS FORUM, Issue 8 2008Albert Mas I.3.7 Computer Graphics: Three-Dimensional Graphics and Realism Abstract This paper presents a method for compressing measured datasets of the near-field emission of physical light sources (represented by raysets). We create a mesh on the bounding surface of the light source that stores illumination information. The mesh is augmented with information about directional distribution and energy density. We have developed a new approach to smoothly generate random samples on the illumination distribution represented by the mesh, and to efficiently handle importance sampling of points and directions. We will show that our representation can compress a 10 million particle rayset into a mesh of a few hundred triangles. We also show that the error of this representation is low, even for very close objects. [source] A System for View-Dependent AnimationCOMPUTER GRAPHICS FORUM, Issue 3 2004Parag Chaudhuri In this paper, we present a novel system for facilitating the creation of stylized view-dependent 3D animation. Our system harnesses the skill and intuition of a traditionally trained animator by providing a convivial sketch based 2D to 3D interface. A base mesh model of the character can be modified to match closely to an input sketch, with minimal user interaction. To do this, we recover the best camera from the intended view direction in the sketch using robust computer vision techniques. This aligns the mesh model with the sketch. We then deform the 3D character in two stages - first we reconstruct the best matching skeletal pose from the sketch and then we deform the mesh geometry. We introduce techniques to incorporate deformations in the view-dependent setting. This allows us to set up view-dependent models for animation. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism - Animation 7 Figure 7. Our system takes as input a sketch (a), and a base mesh model (b), then recovers a camera to orient the base mesh (c), then reconstructs the skeleton pose (d), and finally deforms the mesh to find the best possible match with the sketch (e). [source] Dye Advection Without the Blur: A Level-Set Approach for Texture-Based Visualization of Unsteady FlowCOMPUTER GRAPHICS FORUM, Issue 3 2004D. Weiskopf Dye advection is an intuitive and versatile technique to visualize both steady and unsteady flow. Dye can be easily combined with noise-based dense vector field representations and is an important element in user-centric visual exploration processes. However, fast texture-based implementations of dye advection rely on linear interpolation operations that lead to severe diffusion artifacts. In this paper, a novel approach for dye advection is proposed to avoid this blurring and to achieve long and clearly defined streaklines or extended streak-like patterns. The interface between dye and background is modeled as a level-set within a signed distance field. The level-set evolution is governed by the underlying flow field and is computed by a semi-Lagrangian method. A reinitialization technique is used to counteract the distortions introduced by the level-set evolution and to maintain a level-set function that represents a local distance field. This approach works for 2D and 3D flow fields alike. It is demonstrated how the texture-based level-set representation lends itself to an efficient GPU implementation and therefore facilitates interactive visualization. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism [source] GPU-Based Nonlinear Ray TracingCOMPUTER GRAPHICS FORUM, Issue 3 2004Daniel Weiskopf In this paper, we present a mapping of nonlinear ray tracing to the GPU which avoids any data transfer back to main memory. The rendering process consists of the following parts: ray setup according to the camera parameters, ray integration, ray-object intersection, and local illumination. Bent rays are approximated by polygonal lines that are represented by textures. Ray integration is based on an iterative numerical solution of ordinary differential equations whose initial values are determined during ray setup. To improve the rendering performance, we propose acceleration techniques such as early ray termination and adaptive ray integration. Finally, we discuss a variety of applications that range from the visualization of dynamical systems to the general relativistic visualization in astrophysics and the rendering of the continuous refraction in media with varying density. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism [source] Hardware-Accelerated Rendering of Photo HullsCOMPUTER GRAPHICS FORUM, Issue 3 2004Ming Li This paper presents an efficient hardware-accelerated method for novel view synthesis from a set of images or videos. Our method is based on the photo hull representation, which is the maximal photo-consistent shape. We avoid the explicit reconstruction of photo hulls by adopting a view-dependent plane-sweeping strategy. From the target viewpoint slicing planes are rendered with reference views projected onto them. Graphics hardware is exploited to verify the photo-consistency of each rasterized fragment. Visibilities with respect to reference views are properly modeled, and only photo-consistent fragments are kept and colored in the target view. We present experiments with real images and animation sequences. Thanks to the more accurate shape of the photo hull representation, our method generates more realistic rendering results than methods based on visual hulls. Currently, we achieve rendering frame rates of 2,3 fps. Compared to a pure software implementation, the performance of our hardware-accelerated method is approximately 7 times faster. Categories and Subject Descriptors (according to ACM CCS): CR Categories: I.3.3 [Computer Graphics]: Picture/Image Generation; I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism. [source] Hierarchical Higher Order Face Cluster Radiosity for Global Illumination Walkthroughs of Complex Non-Diffuse EnvironmentsCOMPUTER GRAPHICS FORUM, Issue 3 2003Enrico Gobbetti We present an algorithm for simulating global illumination in scenes composed of highly tessellated objects withdiffuse or moderately glossy reflectance. The solution method is a higher order extension of the face cluster radiositytechnique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order baseswith a modified progressive shooting iteration to rapidly produce visually continuous solutions with limited memoryrequirements. The output of the method is a vector irradiance map that partitions input models into areaswhere global illumination is well approximated using the selected basis. The programming capabilities of moderncommodity graphics architectures are exploited to render illuminated models directly from the vector irradiancemap, exploiting hardware acceleration for approximating view dependent illumination during interactive walkthroughs.Using this algorithm, visually compelling global illumination solutions for scenes of over one millioninput polygons can be computed in minutes and examined interactively on common graphics personal computers. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture and Image Generation; I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism. [source] Visyllable Based Speech AnimationCOMPUTER GRAPHICS FORUM, Issue 3 2003Sumedha Kshirsagar Visemes are visual counterpart of phonemes. Traditionally, the speech animation of 3D synthetic faces involvesextraction of visemes from input speech followed by the application of co-articulation rules to generate realisticanimation. In this paper, we take a novel approach for speech animation , using visyllables, the visual counterpartof syllables. The approach results into a concatenative visyllable based speech animation system. The key contributionof this paper lies in two main areas. Firstly, we define a set of visyllable units for spoken English along withthe associated phonological rules for valid syllables. Based on these rules, we have implemented a syllabificationalgorithm that allows segmentation of a given phoneme stream into syllables and subsequently visyllables. Secondly,we have recorded the database of visyllables using a facial motion capture system. The recorded visyllableunits are post-processed semi-automatically to ensure continuity at the vowel boundaries of the visyllables. We defineeach visyllable in terms of the Facial Movement Parameters (FMP). The FMPs are obtained as a result of thestatistical analysis of the facial motion capture data. The FMPs allow a compact representation of the visyllables.Further, the FMPs also facilitate the formulation of rules for boundary matching and smoothing after concatenatingthe visyllables units. Ours is the first visyllable based speech animation system. The proposed technique iseasy to implement, effective for real-time as well as non real-time applications and results into realistic speechanimation. Categories and Subject Descriptors (according to ACM CCS): 1.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism [source] Progressive Hulls for Intersection ApplicationsCOMPUTER GRAPHICS FORUM, Issue 2 2003Nikos Platis Abstract Progressive meshes are an established tool for triangle mesh simplification. By suitably adapting the simplification process, progressive hulls can be generated which enclose the original mesh in gradually simpler, nested meshes. We couple progressive hulls with a selective refinement framework and use them in applications involving intersection queries on the mesh. We demonstrate that selectively refinable progressive hulls considerably speed up intersection queries by efficiently locating intersection points on the mesh. Concerning the progressive hull construction, we propose a new formula for assigning edge collapse priorities that significantly accelerates the simplification process, and enhance the existing algorithm with several conditions aimed at producing higher quality hulls. Using progressive hulls has the added advantage that they can be used instead of the enclosed object when a lower resolution of display can be tolerated, thus speeding up the rendering process. ACM CSS: I.3.3 Computer Graphics,Picture/Image Generation, I.3.5 Computer Graphics,Computational Geometry and Object Modeling, I.3.7 Computer Graphics,Three-Dimensional Graphics and Realism [source] The Perspective Silhouette of a Canal SurfaceCOMPUTER GRAPHICS FORUM, Issue 1 2003Ku-Jin Kim We present an efficient and robust algorithm for parameterizing the perspective silhouette of a canal surface and detecting each connected component of the silhouette. A canal surface is the envelope of a moving sphere with varying radius, defined by the trajectoryC(t)of its center and a radius functionr(t). This moving sphere,S(t), touches the canal surface at a characteristic circleK(t). We decompose the canal surface into a set of characteristic circles, compute the silhouette points on each characteristic circle, and then parameterize the silhouette curve. The perspective silhouette of the sphereS(t)from a given viewpoint consists of a circleQ(t); by identifying the values oftat whichK(t)andQ(t)touch, we can find all the connected components of the silhouette curve of the canal surface. ACM CSS: I.3.7 Computer Graphics,Three Dimensional Graphics and Realism [source] Local Physical Models for Interactive Character AnimationCOMPUTER GRAPHICS FORUM, Issue 3 2002Sageev Oore Our goal is to design and build a tool for the creation of expressive character animation. Virtual puppetry, also known as performance animation, is a technique in which the user interactively controls a character's motion. In this paper we introduce local physical models for performance animation and describe how they can augment an existing kinematic method to achieve very effective animation control. These models approximate specific physically-generated aspects of a character's motion. They automate certain behaviours, while still letting the user override such motion via a PD-controller if he so desires. Furthermore, they can be tuned to ignore certain undesirable effects, such as the risk of having a character fall over, by ignoring corresponding components of the force. Although local physical models are a quite simple approximation to real physical behaviour, we show that they are extremely useful for interactive character control, and contribute positively to the expressiveness of the character's motion. In this paper, we develop such models at the knees and ankles of an interactively-animated 3D anthropomorphic character, and demonstrate a resulting animation. This approach can be applied in a straight-forward way to other joints. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism, Interaction Techniques [source] Thug Realism: Inhabiting Fantasy in Urban TanzaniaCULTURAL ANTHROPOLOGY, Issue 1 2002Brad Weiss First page of article [source] Indirect Perceptual Realism and Multiple ReferenceDIALECTICA, Issue 3 2008Derek Brown Indirect realists maintain that our perceptions of the external world are mediated by our ,perceptions' of subjective intermediaries such as sensations. Multiple reference occurs when a word or an instance of it has more than one reference. I argue that, because indirect realists hold that speakers typically and unknowingly directly perceive something subjective and indirectly perceive something objective, the phenomenon of multiple reference is an important resource for their view. In particular, a challenge that A. D. Smith has recently put forward for indirect realists can be overcome by appreciating how multiple reference is likely to arise when a projectivist variety of indirect realism is interpreted by speakers adhering to a naďve direct realism. [source] Triangulation: Davidson, Realism and Natural KindsDIALECTICA, Issue 1 2001William Child Is there a plausible middle position in the debate between realists and constructivists about categories or kinds? Such a position may seem to be contained in the account of triangulation that Donald Davidson develops in recent writings. On this account, the kinds we pick out are determined by an interaction between our shared similarity responses and causal relations between us and things in our environment. So kinds and categories are neither imposed on us by the nature of the world, nor imposed by us on an intrinsically unstructured reality. But the picture derivable from Davidson's account of triangulation can be interpreted in either of two ways. On one interpretation, it collapses into constructivism. On the other, it turns out to be very close to the most plausible versions of realism. It is argued that Davidson's attempts to distinguish his view from Putnam's realism about natural kinds are unsuccessful. So Davidson's account of triangulation does indeed suggest a plausible view of kinds. But that view is a version of traditional realist views, not an alternative to them. [source] "God Has Chosen Us": Re-Membering Christian Realism, Rescuing Christendom, and the Contest of Responsibilities during the Cold War*DIPLOMATIC HISTORY, Issue 1 2009Mark Edwards First page of article [source] Women, Law, and Dramatic Realism in Early Modern EnglandENGLISH LITERARY RENAISSANCE, Issue 2 2005SUBHA MUKHERJI First page of article [source] Realism, Prediction, and Foreign PolicyFOREIGN POLICY ANALYSIS, Issue 3 2009Samuel Barkin Attempts by some contemporary realists to both claim that international politics are objectively predictable and at the same time prescribe particular foreign policies cannot hold together logically, because they are internally contradictory. The core argument of this article is that these attempts not only fail to fulfill their goal, but that the attempt to be scientific, to see the world as predictable, is ontologically incompatible with the core insight of classical realism, that we must see the world as it is, rather than as we want it to be. There are two ramifications of this observation for a realism that is not internally contradictory. The first is that a prescriptive realism must be a theory of foreign policy, not a theory of systems structure. And the second is that a realism that works as a theory of foreign policy prediction needs to be reflexive, needs to examine its own assumptions and biases as an integral part of the process of studying international politics. [source] Brecht and Sinn und Form: The Creation of Cold War LegendsGERMAN LIFE AND LETTERS, Issue 4 2007Stephen Parker ABSTRACT Brecht and Peter Huchel's Sinn und Form are among the few examples of early GDR cultural life with a genuine capacity to accumulate cultural capital on the international stage. The analysis of Brecht's collaboration with Sinn und Form in the Deutsche Akademie der Künste offers a fresh perspective upon their attainment of a legendary pre-eminence in German cultural life during the Cold War. Brecht's espousal of Marxism-Leninism and of a relative artistic autonomy, informed by political constraints, ensured some common ground with the SED leadership. However, the Party's enforcement of a binary opposition between Socialist Realism and Formalism became a crucial field of conflict, spawning major illusions and antagonisms between the artistic and political elites. In key contributions to Sinn und Form, Brecht foregrounded aesthetic considerations and historical responsibility, yet the SED's nationalistic discourse colouring Socialist Realism was motivated by the geopolitical imperative of justifying the GDR's status among the people's democracies of the Eastern Bloc. This, in turn, justified the SED's subordination of cultural to political capital, dismissing the claims of elite culture in a series of staged events. The position of Brecht and his supporters was relentlessly eroded until, quite improbably, the crisis of 17 June 1953 allowed them to turn the tables. While popular opposition was suppressed, Brecht simultaneously re-affirmed his loyalty to the weakened SED leadership, whose revolutionary achievements he continued to praise, and re-asserted the relative autonomy of the elite Akademie and its journal. Brecht and Sinn und Form capitalised upon their enhanced reputations, securing the legendary status that later repression did nothing to diminish. [source] Evaluation of six process-based forest growth models using eddy-covariance measurements of CO2 and H2O fluxes at six forest sites in EuropeGLOBAL CHANGE BIOLOGY, Issue 3 2002K. Kramer Abstract Reliable models are required to assess the impacts of climate change on forest ecosystems. Precise and independent data are essential to assess this accuracy. The flux measurements collected by the EUROFLUX project over a wide range of forest types and climatic regions in Europe allow a critical testing of the process-based models which were developed in the LTEEF project. The ECOCRAFT project complements this with a wealth of independent plant physiological measurements. Thus, it was aimed in this study to test six process-based forest growth models against the flux measurements of six European forest types, taking advantage of a large database with plant physiological parameters. The reliability of both the flux data and parameter values itself was not under discussion in this study. The data provided by the researchers of the EUROFLUX sites, possibly with local corrections, were used with a minor gap-filling procedure to avoid the loss of many days with observations. The model performance is discussed based on their accuracy, generality and realism. Accuracy was evaluated based on the goodness-of-fit with observed values of daily net ecosystem exchange, gross primary production and ecosystem respiration (gC m,2 d,1), and transpiration (kg H2O m,2 d,1). Moreover, accuracy was also evaluated based on systematic and unsystematic errors. Generality was characterized by the applicability of the models to different European forest ecosystems. Reality was evaluated by comparing the modelled and observed responses of gross primary production, ecosystem respiration to radiation and temperature. The results indicated that: Accuracy. All models showed similar high correlation with the measured carbon flux data, and also low systematic and unsystematic prediction errors at one or more sites of flux measurements. The results were similar in the case of several models when the water fluxes were considered. Most models fulfilled the criteria of sufficient accuracy for the ability to predict the carbon and water exchange between forests and the atmosphere. Generality. Three models of six could be applied for both deciduous and coniferous forests. Furthermore, four models were applied both for boreal and temperate conditions. However, no severe water-limited conditions were encountered, and no year-to-year variability could be tested. Realism. Most models fulfil the criterion of realism that the relationships between the modelled phenomena (carbon and water exchange) and environment are described causally. Again several of the models were able to reproduce the responses of measurable variables such as gross primary production (GPP), ecosystem respiration and transpiration to environmental driving factors such as radiation and temperature. Stomatal conductance appears to be the most critical process causing differences in predicted fluxes of carbon and water between those models that accurately describe the annual totals of GPP, ecosystem respiration and transpiration. As a conclusion, several process-based models are available that produce accurate estimates of carbon and water fluxes at several forest sites of Europe. This considerable accuracy fulfils one requirement of models to be able to predict the impacts of climate change on the carbon balance of European forests. However, the generality of the models should be further evaluated by expanding the range of testing over both time and space. In addition, differences in behaviour between models at the process level indicate requirement of further model testing, with special emphasis on modelling stomatal conductance realistically. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||