Single-picture reconstruction and rendering of trees for plausible vegetation synthesis

State-of-the-art approaches for tree reconstruction either put limiting constraints on the input side (requiring multiple photographs, a scanned point cloud or intensive user input) or provide a representation only suitable for front views of the tree. In this paper we present a complete pipeline for synthesizing and rendering detailed trees from a single photograph with minimal user effort. Since the overall shape and appearance of each tree is recovered from a single photograph of the tree crown, artists can benefit from georeferenced images to populate landscapes with native tree species. A key element of our approach is a compact representation of dense tree crowns through a radial distance map. Our first contribution is an automatic algorithm for generating such representations from a single exemplar image of a tree. We create a rough estimate of the crown shape by solving a thin-plate energy minimization problem, and then add detail through a simplified shape-from-shading approach. The use of seamless texture synthesis results in an image-based representation that can be rendered from arbitrary view directions at different levels of detail. Distant trees benefit from an output-sensitive algorithm inspired on relief mapping. For close-up trees we use a billboard cloud where leaflets are distributed inside the crown shape through a space colonization algorithm. In both cases our representation ensures efficient preservation of the crown shape. Major benefits of our approach include: it recovers the overall shape from a single tree image, involves no tree modeling knowledge and minimal authoring effort, and the associated image-based representation is easy to compress and thus suitable for network streaming.Peer ReviewedPostprint (author's final draft

Reconstructing Plants in 3D from a Single Image Using Analysis-by-Synthesis

International audienceMature computer vision techniques allow the reconstruction of challenging 3D objects from images. However, due to high complexity of plant topology, dedicated methods for generating 3D plant models must be devised. We propose to generate a 3D model of a plant, using an analysis-by-synthesis method mixing information from a single image and a priori knowledge of the plant species. First, our dedicated skeletonisation algorithm generates a possible branch- ing structure from the foliage segmentation. Then, a 3D generative model, based on a parametric model of branching systems that takes into ac- count botanical knowledge is built. The resulting skeleton follows the hierarchical organisation of natural branching structures. An instance of a 3D model can be generated. Moreover, varying parameter values of the generative model (main branching structure of the plant and foliage), we produce a series of candidate models. The reconstruction is improved by selecting the model among these proposals based on a matching criterion with the image. Realistic results obtained on di erent species of plants illustrate the performance of the proposed method

Spatial Reconstruction of Biological Trees from Point Cloud

Trees are complex systems in nature whose topology and geometry ar

Closed Contour Fractal Dimension Estimation by the Fourier Transform

This work proposes a novel technique for the numerical calculus of the fractal dimension of fractal objects which can be represented as a closed contour. The proposed method maps the fractal contour onto a complex signal and calculates its fractal dimension using the Fourier transform. The Fourier power spectrum is obtained and an exponential relation is verified between the power and the frequency. From the parameter (exponent) of the relation, it is obtained the fractal dimension. The method is compared to other classical fractal dimension estimation methods in the literature, e. g., Bouligand-Minkowski, box-couting and classical Fourier. The comparison is achieved by the calculus of the fractal dimension of fractal contours whose dimensions are well-known analytically. The results showed the high precision and robustness of the proposed technique

Development of methods for characterizing plant and stand architectures and for model comparisons

Diese Arbeit steht im Kontext der individuenbasierten Baumbestandesmodellierung mit vereinfachten Kronenarchitekturen. Die klassische Forstwirtschaft hat in der Vergangenheit sehr einfach strukturierte Bestände erzeugt, die man mit einfachen Modellen wie Ertragstafeln sehr präzise abbilden kann. Individuenbasierte Modelle mit vereinfachten Architekturen haben dagegen zum Ziel, die klassischen statistischen Ansätze zu ersetzen, da diese das Wachstum von heterogenen Beständen, die teilweise einer sich ver andernden Umgebung ausgesetzt sind, nicht mehr präzise vorhersagen k onnen. Ziel dieser Arbeit ist es, in diesem Bereich der Bestandesmodellierung regelbasierte Sprachen f ur ihre Umsetzung einzuführen. Hierdurch wird die Transparenz bei der Umsetzung und Publikation verbessert. Eine weitere Zielsetzung betrifft die Modellierung bzw. Simulation von Naturverjüngung. Die Problematik bei der Modellierung von Naturverjüngung im Allgemeinen ist die Parametrisierung mit Realdaten: Die Datenaufnahme ist sehr aufwändig. Diese Arbeit zeigt auf, dass es möglich ist, derartige Modelle unter Zuhilfenahme von komplexeren Struktur-Funktions-Modellen (hier das finnische Modell LIGNUM) am Beispiel von jungen Kiefern (Pinus sylvstris L.) zu parametrisieren. Das Beispiel umfasst ein einfaches Modell für das Wachstum von Jungkiefern unter lichtreduzierendem Einfluss einer Schirmlücke. Die Parametrisierung geschieht über einen Aggregationsprozess der LIGNUM-Ergebnisse, der die Grundlage für das vereinfachte, regelbasierte Modell liefert

Preserving Local Ornament Through Algorithm

This study employs fractal algorithms to generate and transform original Aceh ornaments into architectural design elements. The interpretation and generation of this ornaments by fractal method uses L-system based software called jBatik. We studied an approach of preserving local ornaments using three stages: understanding the local ornament geometry function, interpreting and generating new ornament using fractal method, exploring the possible iterations of patterns based on fractal algorithms. We applied this process into architectural design experiments where the 3D patterns used as an architectural design elements. The result shows that the possibility of preserving local ornament by fractal method can open opportunity for architects to explore new approach in design using the iteration and transformation of local ornaments. The endless possibilities offered by fractal method for generating new ornaments justify the digital advancement for its preservation

Impairment in predictive processes during auditory mismatch negativity in ScZ: evidence from event-related fields

Patients with schizophrenia (ScZ) show pronounced dysfunctions in auditory perception but the underlying mechanisms as well as the localization of the deficit remain unclear. To examine these questions, the current study examined whether alterations in the neuromagnetic mismatch negativity (MMNm) in ScZ-patients could involve an impairment in sensory predictions in local sensory and higher auditory areas. Using a whole-head MEG-approach, we investigated the MMNm as well as P300m and N100m amplitudes during a hierarchical auditory novelty paradigm in 16 medicated ScZ-patients and 16 controls. In addition, responses to omitted sounds were investigated, allowing for a critical test of the predictive coding hypothesis. Source-localization was performed to identify the generators of the MMNm, omission responses as well as the P300m. Clinical symptoms were examined with the positive and negative syndrome scale. Event-related fields (ERFs) to standard sounds were intact in ScZ-patients. However, the ScZ-group showed a reduction in the amplitude of the MMNm during both local (within trials) and global (across trials) conditions as well as an absent P300m at the global level. Importantly, responses to sound omissions were reduced in ScZ-patients which overlapped both in latency and generators with the MMNm sources. Thus, our data suggest that auditory dysfunctions in ScZ involve impaired predictive processes that involve deficits in both automatic and conscious detection of auditory regularities