The teaching of African languages to European students: The role of linguistic pragmatics illustrated by Swahili

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The iron crafts of the Swahili from the perspective of historical semantics

To this day research in pre-colonial Swahili history has only taken casual notice of the role of Swahili crafts. This applies in particular to blacksmithing and iron smelting. Probably iron smelting were among the driving factors of cultural contact and of the development of economical structures on the Swahili Coast. Kusimba postulates that metallurgy played an important role for cultural change within Swahili polities. Foreign trade in iron products to other parts of the Indian Ocean fostered local exchange systems that linked the East African settlements on the Coast to each other and the interior (1996:387). In this article the potential of linguistic research on iron crafts for Swahili historiography will be demonstrated, though it has to be emphasised that linguistic evidence is as of yet too scarce to allow more than preliminary results. Two steps are deemed necessary to achieve this aim. In a first step the scientific contributions by historical linguistics, history, and archaeology in regard to Swahili iron working will be reviewed. In a second step it will be demonstrated that historical semantics, together with language geography can make a significant contribution to this discussion. More than anything else, it is the semantic aspect of language that is capable of revealing pre-colonial cultural change in Africa. With comparative phonological and morphological methods historical genetic relationships within a given language family can be discovered

Fast distance field interpolation for reconstruction of surfaces from contoursure

One simple and robust way to get a reconstruction of surfaces from a given contour stack dealing well with branching and other problems which are generally difficult to solve is based on the well known MC-algorithm. To overcome the staircase artefacts produced by the MC-algorithm Jones et. al. [3] proposed to use a distance field interpolation between the slices and to run the MC-algorithm on this distance field. The main problem of this approach is the distance field computation as it is very time consuming especially if high resolution grids (e.g. 1024 x 1024 are used. Therefore, in the original algorithm the resolution of the chosen grid is much less than the resolution of the given contour sacrificing accuracy of the resulting surface. Especially in medical applications this is not accepted by the doctors. In this paper we introduce a new method for the computation of the discrete distance field, which is a breaktrough in terms of speed and accuracy. This new method allows us to reconstruct surfaces from contour stacks with guaranteed accuracy in reasonable time. Several examples show the power of this approach.Veröffentlichung des Wilhelm-Schickard-Institut für Informatik Universität Tübinge

Easy-to-use calibration of multiple-camera setups

Calibration of the pinhole camera model has a well-established theory, especially in the presence of a known calibration object. Unfortunately, in wide-base multi-camera setups, it is hard to create a calibration object, which is visible by all the cameras simultaneously. This results in the fact that conventional calibration methods do not scale well. Using well-known algorithms, we developed a streamlined calibration method, which is able to calibrate multi-camera setups only with the help of a planar calibration object. The object does not have to be observed by at the same time by all the cameras involved in the calibration. Our algorithm breaks down the calibration into four consecutive steps: feature extraction, distortion correction, intrinsic and finally extrinsic calibration. We also made the implementation of the presented method available from our website

FPO++: Efficient Encoding and Rendering of Dynamic Neural Radiance Fields by Analyzing and Enhancing Fourier PlenOctrees

Fourier PlenOctrees have shown to be an efficient representation for real-time rendering of dynamic Neural Radiance Fields (NeRF). Despite its many advantages, this method suffers from artifacts introduced by the involved compression when combining it with recent state-of-the-art techniques for training the static per-frame NeRF models. In this paper, we perform an in-depth analysis of these artifacts and leverage the resulting insights to propose an improved representation. In particular, we present a novel density encoding that adapts the Fourier-based compression to the characteristics of the transfer function used by the underlying volume rendering procedure and leads to a substantial reduction of artifacts in the dynamic model. Furthermore, we show an augmentation of the training data that relaxes the periodicity assumption of the compression. We demonstrate the effectiveness of our enhanced Fourier PlenOctrees in the scope of quantitative and qualitative evaluations on synthetic and real-world scenes