Finite Element Method for Rectification of Architectural Heritage Images of National Importance
Kamal Jain
Member CIPA TG-2
Department of Civil Engineering,
Indian Institute of Technology,
Roorkee – 247667, Uttranchal State, India
Email: kjainfce@iitr.ac.in
P.K. Garg
Member CIPA TG-2
Abstract
Photogrammetry has many advantages as a technique for the acquisition of facade information of the cultural heritage. However, the photogrammetric process to extract facade information from stereo images is often considered to be too labor-intensive and complicated. As a result of this consideration, existing images are often not used for a photogrammetric documentation of the object.
Photogrammetric single image techniques, like the generation of rectified images and orthoimages are well suited for use in architecture and monument preservation. They combine true scale geometric measurements with full image information under quite inexpensive production costs. Especially in the field of architectural orthoimage generation, the combination of image processing with photogrammetric systems provides new solutions.
An image rectification methodology for the reconstruction of destroyed historical buildings using single-view photographs has been presented in this work. Certain feature-oriented properties, like linearity, parallelism, perpendicularity, symmetry etc., of these historical buildings have been used in addition to the information extracted from the images. It has been assumed that neither camera information nor stereo views are available.
The method has been compared with the prevalent methods based on Projective, Polynomial and Affine transformation. The proposed method first generates image of equivalent grids from an available one using perspective geometry. Thereby extending the control throughout the image. Each image grid is then mapped on to the actual grid using finite element interpolation function. Since mapping is done taking the grid points as node points, the method automatically does mosaicking of different pieces.
1. Introduction
Digital rectification with digital image utilizes a personal computer with analytical photogrammetry solution. There are two classes of rectification approaches: the parametric and the non-parametric approaches. Whereas for the parametric approach, the knowledge of the interior and exterior orientation parameters is required, non-parametric approach requires more number of control points.
