KEYWORDS: 3D modeling, Wavelets, Image filtering, Data modeling, 3D image enhancement, Laser scanners, 3D image processing, 3D scanning, Eye models, Optical filters
We present the results we obtained in comparing several carved panels from two high crosses. In this study, which was
carried out as part of the RTE Cork TV program "Secrets of the Stones", we compared three panels of the Cross of the
Scriptures from the Clonmacnois monastic site, Co. Offaly with similar panels from the Cross of Durrow, located in the
grounds of St Columba monastery, Co. Offaly. The purpose of the study was to decide whether these high crosses, which
both date back to the ninth century, could have been carved by the same Celtic artist. The Cross of the Scriptures was
scanned in August 2008 using our Polhemus FastSCAN handheld laser scanner, while the Cross of Durrow was surveyed
in May 2008 by the Germany based, ArcTron 3D company, commissioned by the Offaly County Council. Using the data
from the 3D scans, details of each panel were enhanced using a wavelet filtering technique and a false colour image of
the depth field was computed for each panel. These images were then used as textures and applied back onto the 3D
models. This process allowed for expert historians to later on evaluate, by looking and manipulating the textured 3D
models, the hypothesis that the panels were carved by the same person.
KEYWORDS: 3D modeling, Data modeling, Laser scanners, 3D scanning, Reverse modeling, Wavelets, Clouds, Cultural heritage, Optical filters, 3D acquisition
National monuments are at ever-increasing risk of severe and permanent damage. The 3D laser scanning of stone monuments brings a new dimension in the field of cultural heritage by providing means of preserving, visualizing, accessing and analysing some of its most invaluable artefacts. In this article, we present the results obtained with our project "Profilometry of Medieval Irish Stone Monuments" hosted at the Centre for the Study of Human Settlement and Historical Change, NUI Galway. This project aims to create a virtual archive of selected incised stones from 3D scans taken in the field. The raw scans are processed into watertight 3D models and new processing techniques have been developed to enhance the surface features of the stones. Also, textured 3D models of the artefacts have been made available online for the benefit of both the historian community and the broader public. This article focuses on the analysis we performed on the shaft of the east cross at Toureen Peacaun, Co Tipperary, which shows the longest inscription in Ireland with geometrical capitals.
This article tackles the classic super-resolution (SR) problem Elad99 of obtaining a high-resolution (HR) still image from a sequence of low-resolution (LR) images that have been warped and sub-sampled. The goal here is to recover frequencies higher than the Nyquist frequency by merging the LR information. We focus on the critical step of the SR process before any fusion technique can be applied which consists of the registration of LR images with an arbitrary reference image at sub-pixel accuracy. We propose a registration algorithm for color images, derived from the one described by Djamdji and Bijaoui in Ref. 2. This algorithm achieves automatic feature-based registration at sub-pixel accuracy. It seeks to take advantage of the multi-band (RGB) information in a color image to improve the robustness and accuracy compared to more usual greyscale registration. The fusion of the data from LR images into a higher resolution image is then carried out through thin plate spline interpolation. The results show the algorithm's performance for simulated image sets. The influence of several parameters on the registration algorithm is described.
We use an automatic re-registering of frames taken from a surveillance video to improve signal-to-noise in regions of particular interest. A wavelet transform with automatic signal and noise estimation is used for this purpose. We describe the results obtained using a short surveillance video sequence.
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