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An invariant related to Gaussian curvature at an object point is developed based upon the covariance matrix of photometric values related to surface normals within a local neighborhood about the point. We employ three illumination... more
An invariant related to Gaussian curvature at an object point is developed based upon the covariance matrix of photometric values related to surface normals within a local neighborhood about the point. We employ three illumination conditions, two of which are completely unknown. We never need to explicitly know the surface normal at a point. The determinant of the covariance matrix
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ABSTRACT In this paper, we propose a monocular vision system for approach and landing using a low-cost micro aerial vehicle (MAV). The system enables an off-the-shelf Parrot AR.Drone 2.0 quadrotor MAV to autonomously detect a landpad,... more
ABSTRACT In this paper, we propose a monocular vision system for approach and landing using a low-cost micro aerial vehicle (MAV). The system enables an off-the-shelf Parrot AR.Drone 2.0 quadrotor MAV to autonomously detect a landpad, approach it, and land on it. Particularly, we exploit geometric properties of a circular landpad marker in order to estimate the exact flight distance between the quadrotor and the landing spot. We then employ monocular simultaneous localization and mapping (SLAM) to fly towards the landpad while accurately following a trajectory. Notably, our system does not require the landpad to be located directly underneath the MAV.
ABSTRACT Thyroid nodule segmentation is a hard task due to different echo structures, textures and echogenicities in ultrasound (US) images as well as speckle noise. Currently, a typical clinical evaluation involves the manual,... more
ABSTRACT Thyroid nodule segmentation is a hard task due to different echo structures, textures and echogenicities in ultrasound (US) images as well as speckle noise. Currently, a typical clinical evaluation involves the manual, approximate measurement in two section planes in order to obtain an estimate of the nodule’s size. The aforementioned nodule attributes are recorded on paper. We propose instead the semi-automatic segmentation of 2D slices of acquired 3D US volumes with power watersheds (PW) independent of the nodule type. We tested different input seeds to evaluate the potential of the applied algorithm. On average we achieved a 76.81 % sensitivity, 88.95 % precision and 0.81 Dice coefficient. The runtime on a standard PC is about 0.02 s which indicates that the extension to 3D volume data should be feasible.
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We present a novel robust methodology for corresponding a dense set of points on an object surface from photometric values, for 3-D stereo computation of depth. The method- ology utilizes multiple stereo pairs of images, each stereo pair... more
We present a novel robust methodology for corresponding a dense set of points on an object surface from photometric values, for 3-D stereo computation of depth. The method- ology utilizes multiple stereo pairs of images, each stereo pair taken of exactly the same scene but under different illumination. With just 2 stereo pairs of images taken respec- tively for 2
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ABSTRACT We present a system for forecasting occlusions of the sun and the expected Global Horizontal Irradiance (GHI) for solar power plants. Our system uses non-rigid registration for detecting cloud motion and a Kalman filter to... more
ABSTRACT We present a system for forecasting occlusions of the sun and the expected Global Horizontal Irradiance (GHI) for solar power plants. Our system uses non-rigid registration for detecting cloud motion and a Kalman filter to establish continuous forecasts for up to 10 min. The optimal parameters of the system are determined through the use of the binary classification metrics Precision, Recall and F2F2 Score while evaluating the forecasting of occlusions. The Kalman filter and the use of a dense motion field instead of a global cloud speed prove to be key elements of the forecasting pipeline: by incorporating information from previous forecasts into the current one, a Kalman filtering facilitates forecasting times below 3 min and the dense motion field enhances the accuracy of our forecasts. Our evaluation of the proposed approach on 15 days of real world data collected in Kitzingen, Bavaria, Germany, produced a mean RMSE for forecasting GHI of (164±9)(164±9) W m−2.
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... 2 International Max Planck Research School for Optics and Imaging 3 Erlangen Graduate School in Advanced Optical Technologies (SAOT), Erlangen, Germany {eva.eibenberger, elli ... 4. As illuminant estimation technique the voting scheme... more
... 2 International Max Planck Research School for Optics and Imaging 3 Erlangen Graduate School in Advanced Optical Technologies (SAOT), Erlangen, Germany {eva.eibenberger, elli ... 4. As illuminant estimation technique the voting scheme by Riess et al.[16] was chosen. 5.2. ...
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Local surface curvature is an important shape descriptor, especially for smooth featureless objects. For this family of objects, if their surface is matte, there is a one-to-one mapping between their surface normal map and the photometric... more
Local surface curvature is an important shape descriptor, especially for smooth featureless objects. For this family of objects, if their surface is matte, there is a one-to-one mapping between their surface normal map and the photometric data collected from a scene under three different illumination conditions. This mapping allows for the extraction of the sign and the magnitude of Gaussian
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We present a methodology for corresponding a dense set of points on an object surface from photometric values for three-dimensional stereo computation of depth. The methodology utilizes multiple stereo pairs of images, with each stereo... more
We present a methodology for corresponding a dense set of points on an object surface from photometric values for three-dimensional stereo computation of depth. The methodology utilizes multiple stereo pairs of images, with each stereo pair being taken of the identical scene but under different illumination. With just two stereo pairs of images taken under two different illumination conditions, a
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The majority of color work in machine vision has been based on a trichromatic (and spe- cifically RGB) color representation. In reality, color is a continuous univariate function of wavelength which can be quantized into an arbitrary... more
The majority of color work in machine vision has been based on a trichromatic (and spe- cifically RGB) color representation. In reality, color is a continuous univariate function of wavelength which can be quantized into an arbitrary number of dimensions. The capture of reflectance information in spectrally higher dimensions will improve image analysis. To acquire spectrally and spatially high-dimensional images, one has to employ special- ized image acquisition devices. This paper is a survey of the currently available technolo- gies for this type of imaging systems. Electronically tunable filters offer the fastest, most accurate and flexible color filtering techniques that are currently available. We provide an overview of this type of filters and present a set of criteria for selecting the appropriate device depending on the specific application requirements.
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This article describes a new method of Shape from Shading, Shape from Isophotes. Shape from Isophotes uses the image isophotes for recovering the object surface normals. It is a propagation method. It initially directly recovers a small... more
This article describes a new method of Shape from Shading, Shape from Isophotes. Shape from Isophotes uses the image isophotes for recovering the object surface normals. It is a propagation method. It initially directly recovers a small number of surface normals and then uses them to estimate normals at neighboring points in either adjacent isophotes or within the same isophote.
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... 51, 53, 55, 61, 64, 66, 71, 74, 95 Huber, Martin, 28 Jäger, Florian, 27 Kappler, Steffen, 17 Keck, Benjamin, 33 Kollorz, Eva Nicole Karin ... 89 Nöth, Elmar, 81 Penne, Jochen, 64, 66, 71, 72, 74, 91 Prümmer Marcus, 3 Raupach, Rainer,... more
... 51, 53, 55, 61, 64, 66, 71, 74, 95 Huber, Martin, 28 Jäger, Florian, 27 Kappler, Steffen, 17 Keck, Benjamin, 33 Kollorz, Eva Nicole Karin ... 89 Nöth, Elmar, 81 Penne, Jochen, 64, 66, 71, 72, 74, 91 Prümmer Marcus, 3 Raupach, Rainer, 17 Redel, Thomas, 35 Riess, Christian, 105 Ritt ...
Research Interests: Medical()
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We compute the sign of Gaussian curvature using a purely geometric definition. Consider a point p on a smooth surface S and a closed curve γ on S which encloses p. The image of γ on the unit normal Gaussian sphere is a new curve β. The... more
We compute the sign of Gaussian curvature using a purely geometric definition. Consider a point p on a smooth surface S and a closed curve γ on S which encloses p. The image of γ on the unit normal Gaussian sphere is a new curve β. The Gaussian curvature at p is defined as the ratio of the area enclosed by γ over the area enclosed by β as γ contracts to p. The sign of Gaussian curvature at p is determined by the relative orientations of the closed curves γ and β. We directly compute the relative orientation of two such curves from intensity data. We employ three unknown illumination conditions to create a photometric scatter plot. This plot is in one-to-one correspondence with the subset of the unit Gaussian sphere containing the mutually illuminated surface normal. This permits direct computation of the sign of Gaussian curvature without the recovery of surface normals. Our method is albedo invariant. We assume diffuse reflectance, but the nature of the diffuse reflectance can be general and unknown. Error analysis on simulated images shows the accuracy of our technique. We also demonstrate the performance of this methodology on empirical data
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... Clusters of signature plots. IIIIIIII ~ - Original Holly Mug Et - - - Normalized Holly Mug -A - A Original X Mug El-I - Normalized X Mug -A-k li - G - - AI b - i t' 1 , I , - 3e+10 - I I I I I I I I n 2.Se+10 - mug +- -... more
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