Science Pictures

3D Reconstruction of a Urban Landscape

3D picture of a urban landscape (town of Amiens, France)
obtained from a stereoscopic pair of aerial photographs.
(DTIM)

The increasing stereoscopic¹ capabilities of radar acquisition system (ERS, RADARSAT) and optical systems (SPOT) allow automatic generation of digital terrain models, which are images where each pixel corresponds to the height of the point represented.

Pairs of stereoscopic images obtained by consecutive photographs taken during flight over a region are transposed after correction by epipolar geometry³. By estimating the disparity² between two images, it is possible to evaluate the relative height of each point. The robustness of the process is ensured by modelling and taking into account the geometric nature of the elements observed (here polyhedral buildings).

The knowledge of building heights in an urban environment is very useful for broadcasts, the land register, topography, etc.

Glossary

1. Stereoscopic
   Characterises the techniques used to reconstruct 3D information about a region from a pair of photographic or other images. The process consists of triangulation of the similar points of the two images.
2. Disparity
   In stereoscopy, difference in position between two similar points located in two images.
3. Epipolar Geometry
   In image processing, géometrie particulière caractérisant les liens entre deux images stéréoscopiques . L'homologue d'un point de l'image de gauche se trouve sur une droite connue dans l'image de droite.

One of the images used to build the 3D model.

Please note: Cortona® VRML Client will allow you to view this demonstration.
Donwload player at: http://www.parallelgraphics.com/products/cortona

Please note that the demo size is 8 MB, so the recommended Internet connection speed is 56k or above.

For optimal use we recommend the minimal computer configuration:

• Operating system: Microsoft® Windows® 9x/ME/NT4.0/2000/XP
• Internet browser: Internet Explorer 4.0+
• Computer (CPU): Pentium® III 800 MHz
• Random Access Memory (RAM): 256MB
• Graphic card: 1024x768x16-bit color, 64MB, OpenGL or Direct3D hardware acceleration

The Cortona viewer is available for Mac OS. For Linux users, an additional plugin is requried. You might use Codeweavers.com, for example. We made no specific tests with these configurations.

Once the plugin is installed, you can run and manipulate the 3D model.

If you do not have a hign speed internet access, you might download our archive file (amiens-vrml.zip). You will find the different elements of the model, without the viewer. To launch the VRML plugin, open the amiens.wrl file.

Since the Cortona player is launched you should follow this steps to display the VRML file correctly :
- open the preference panel
- activate the texture rendering ("use textures mip-maping" option ON)
- choose animate viewpoints option
- choose the viewpoint "Viewpoint2" (using a right click) to display the scene in perspective view cause default view is top view.

Last Update: August 2, 2004 - © ONERA 2009 - Terms of use