1. 1st
intercon+nental
Conference
of
Territorial
Intelligence
IT-Gatineau 2011, Oct. 12-14, 2011
A landscape potential characterization: spatial
template of pedestrian ambient fields within the
urban fabric
P. Woloszyn and T. Leduc
ESO and CERMA Laboratories, CNRS, France

2. Outline
 Context and motivations
 Visual perception using isovists field
 The method we developed
 Use case and results
 Conclusion and outlook

3. Context and motivations : the socio-ecological transition trade-off
Income
distribu7on
law
Powerty/inequality
measurements
Economical
NEEDS
Social
Entropy
Socioeconomical
weight
Entropy
RESOURCE
DEVELOPMENT
Econogical
weight
Socioecological
weight
Environmental
Entropy
Microambients
economics

4. Focus on visual ambiences : isovists field
 The isovist is simply the Gibsonian optic array, with the
wavelength and intensity information omitted,
 It describes local geometrical properties of spaces with respect
to individual observation points and weight all the possible view
directions equally. It is a 2D horizontal slice of pedestrian's
surrounding space;
 The set of all points in an environment of
opaque surfaces that are visible from a
given view-point;
 A useful tool to define the open space
concept (= the empty space, the void,
between the surrounding buildings).

5. Our proposal
 Combine:
 A sort of “surface ray casting” strategy (an angular abscissa
sampling of the star-shaped isovist),
 With a tool from information theory (Shannon entropy),
 So as to produce:
 A sensory based Digital Terrain Model

6. Some more details
 sample the region of interest into a set of punctual
positions
 in each of these punctual locations, determine the
corresponding partial isovist
 convert all these isovists (2D star shaped polygons) into a
set of function of radial distances (dimension reduction
operation)
 let's assume that each function of radial distances
represent a 1D random variable, and compute the
corresponding Shannon entropy value
 represent all these entropy values into a raster color map

7. Function of radial distances and
dimension reduction operation
 Nyquist–Shannon
sampling theorem
 Shannon entropy
computation

8. Use case
 Place Royale square

9. Position #1
H=0.77

10. Position #2
H=0.78

11. Position #3
H=0.86

12. Position #4
H=0.87

13. Position #5
H=0.88

14. Conclusion and outlook
Done
- landscape visual space geo-topical modeling
- angular perspective variability computation
- spatial potential, allowing a pedestrian to diversify his
visual landscape during his walk
- advanced overview of the complexity and the richness
of the urban fabric
Future
Challenge is to investigate the inter-sensorial ambient-
scape as a basis of a multi-sensory conception in
townscape planning and design

15. Acknowledgements
To:
F Gonzalez Cortés (Spain) for all the developments
performed on the GearScape GIS.
And to:
Assistant Professor B Suner (from the National School
of Architecture of Nantes city, France) for his significant
help in the production of the panoramic snapshots.

16. References