Alejandro Troccoli, PhD


Adviser: Prof. Peter Allen
Robotics Lab
Department of Computer Science

I completed my doctoral degree in October 2006 and went to work for NVIDIA in Santa Clara, CA.

Contact information

You can still contact me at:

My complete CV PDF

My research

I did my research in 3D modeling of architectural and archaeological sites using range scans and photographs. My work is a piece of larger project on Computational Tools for Modeling, Visualizing and Analyzing Historic and Archaeological Sites.

Dissertation: New methods and tools for 3D-modeling of large scale outdoor scenes using range and color images [More details] Download [PDF - 26Mb]

My dissertation develops new tools and methods for creating digital models from range and color images, with emphasis in large-scale outdoor scenes. First, it addresses the problem of range and color image registration. In this area, I introduce a semi-automatic tool for range and color image registration that makes use of line-features to solve for the position and orientation of the digital camera. This allows to efficiently register images of urban scenery. Secondly, I present a registration technique that uses the shadows cast by the sun as cues find the correct camera pose, which was successfully applied in the creation of a digital model of an archaeological excavation in Monte Polizzo, Sicily. I also address the problem of building seamless integrated texture maps from images that were taken under different illumination conditions. To achieve this I present two different solutions. The first one is to align all the images to the same illumination. For this, I have developed a technique that computes a relighting operator over the area of overlap of a pair of images, which is then used to relight the entire image. The proposed method can handle images with shadows and can effectively remove the shadows from the image, if required. The second technique uses the ratio of two images to factor out the diffuse reflectance of an image from its illumination. This is achieved without any light measuring device. By computing the actual reflectance we remove from the images any effects of the illumination, which then allows to create new renderings under novel illumination conditions.

Committee members: Prof. Peter Allen, Prof. Shree Nayar, Prof. Ravi Ramamoorthi, Prof. Ioannis Stamos and Prof. Michael Grossberg
Computational Tools for Modeling, Visualizing and Analyzing Historic and Archaeological Sites.
This is an interdisciplinary project that has brought together a team of computer scientists, art historians and archaeologists to provide a set of tools for digitally recording and visualizing and historic and arhchaeological sites. The tools include a database component, a 3D modeling component and an augmented reality application. My work has focused on the 3D modeling aspects, and I have had the chance to participate in several field trips during the last past three years.

3D Modeling the Cathedral of Ste. Pierre, Beauvais, France
This is joint with the Visual Media Center, Department of Art History and Archaeology. The Cathedral of Ste. Pierre, in Beauvais, a town 90km north of Paris, has suffered a number of collapses since it was built in the 1200s, and it might still be in danger. Our lab is building a model of the cathedral. I was part of the team that visited Beauvais in June 2002.
Related papers:   [Computer Graphics and Applications, Nov 2003 PDF ]  -   [ ICRA03, PDF]
3D Modeling the Acropolis at Monte Polizzo, Sicily
In July 2003 we joined the Stanford University Monte Polizzo Excavation in Sicily with the goal of digitally recording an archaeological excavation. We had three goals for this project: to capture the site's current state on a daily basis using several sensors; to create an integrated 3D site model that would include geometry from laser range scans, images and video; and to record changes as different layers wre exposed.
Video: 3D model
Related papers:   [ Shadow registration (IVR04), PDF ]   -   [3DPVT04, PDF]
3D Modeling Thulamela, KNP, South Africa
In May 2004, we went to Kruger National Park in South Africa to scan the ruins of Thulamela.
Modeling and Simulation using the Cell-DEVS formalism
Timed Cell-DEVS is a modeling formalism that extends DEVS (Discrete Event Systems Specification) to the domain of cellular models. Cell-DEVS is a powerfull tool to model complex physical systems. As part of my Tesis de Licenciatura (Master's thesis) I extended the Cell-DEVS tool to run in parallel on a cluster of Linux machines.
Recent publications

Relighting acquired models of outdoor scenes To appear in the 5th International Conference 3-D Digital Imaging and Modeling (3DIM), June 2005.
Alejandro Troccoli and Peter Allen
Paper:     PDF

Seeing into the past: a 3D modeling pipeline for archeological visualization 2nd International Symposium on 3D Data Processing, Visualization and Transmission (3DPVT), Sep 2004.
Peter Allen, Steve Feiner, Alejandro Troccoli, Hrvoje Benko, Edward Ishak and Benjamin Smith.
Paper:     PDF

A shadow based method for image to model registration 2nd IEEE Workshop on Video and Image Registration (IVR), Jul 2004.
Alejandro Troccoli and Peter Allen.
Paper:     PDF
Modeling, Visualizing and Preserving Archaeological Sites. Poster. Joint Conference on Digital Libraries, Jun 2004.
Peter Allen, Steve Feiner, Lynn Meskell, Alejandro Troccoli, Edward Ishak and James Conlon.

New Methods for Digital Modeling of Historic Sites IEEE Computer Graphics and Applications, November 2003.
Peter Allen, Ioannis Stamos, Alejandro Troccoli, Benjamin Smith, M. Leordeanu and Stephen Murray.
Paper:     PDF

Modeling Historic Sites using Range and Image Data Proceedings of ICRA 2003, Tapei. September 2003..
Peter Allen, Ioannis Stamos, Alejandro Troccoli, Benjamin Smith, M. Leordeanu and Y. C. Shu.
Paper:  PDF

The Beauvais Cathedral Project Workshop on Applications of Computer Vision in Archeology. June 2003.
Peter Allen, Alejandro Troccoli, Benjamin Smith, Ioannis Stamos and Stephen Murray.
Paper:     PDF
More publications
Implementing Parallel Cell-DEVS 36th IEEE/SCS Annual Simulation Symposium, April 2003.
Alejandro Troccoli and Gabriel Wainer.
Paper:     PDF
A flow injection model using Cell-DEVS 35th IEEE/SCS Annual Simulation Symposium, April 2002.
Alejandro Troccoli, Javier Ameghino, Fernando Inon and Gabriel Wainer.
Paper:     PDF
Models of complex physical systems using Cell-DEVS 34th IEEE/SCS Annual Simulation Symposium, 2001.
Javier Ameghino, Alejandro Troccoli and Gabriel Wainer.
Paper:     PDF
Performance Analysis of Cellular Models with Parallel Cell-DEVS Summer simulation conference, 2001.
Alejandro Troccoli and Gabriel Wainer.
Paper:     PDF
Using the DEVS paradigm to implement a simulated processor 33rd IEEE/SCS Annual Simulation Symposium, April 2000.
Sergio Daicz, Alejandro Troccoli, Sergio Zlotnik and Gabriel Wainer.
Paper:     PDF

    Last modified on Mar 18th, 2007