3D Modeling: Comparison of some Innovative Techniques of Photogrammetry

Several non-linear problems, typical of analytical photogrammetry and frequent in digital photogrammetry, can be solved with some easy procedures. In this work we propose a two-steps procedure based on two phases: Relative Orientation and Absolute Orientation, both characterized by non-linear functions. In the first step, it is firstly necessary to form the model, finding the solution of the Relative Orientation, and then to reconstruct the object considering the solution of the Absolute Orientation. Subsequently, once validated the technique of orientation of two images, a procedure for the orientation of three images is proposed. The introduction of a third image allows avoiding human decision to find the final solution. In order to find an easy solution for three-image orientation, each model coming from two images of a triplet is analyzed, computing the relative orientation thanks to an exhaustive research of preliminary values of its parameters. This non-conventional approach supplies the orientation of two images, taking into account information among four base solutions. Once each model is relatively registered, the absolute orientation is computed by using a linear parameterization. There is also a comparison between the method of the three photogrammetric images and a method of Computer Vision that allows low costs, automaticity and immediacy: the reconstruction of the 3D model from digital images is performed with algorithms of the Structure from Motion technique (SfM)