costel umr 6554 cnrs gt3 : vegetation in the city: the ... · pdf filepléiades days...

Pléiades Days 17&18 January 2012 - CNES - Toulouse

GT3 : Vegetation in the city: GT3 : Vegetation in the city:

the contribution of VHR datathe contribution of VHR data

[email protected]

[email protected]

[email protected]

Anne PUISSANT1, Eléonore Wolff2, Laurence

Hubert-Moy3

COSTELUMR 6554 CNRS

1. LIVE ERL 7230 CNRS/ Université de Strasbourg2. IGEAT / Université Libre de Bruxelles – ULB3. COSTEL UMR 6554 LETG/ Université Rennes 2

2Pléiades Days 17&18 January 2012 - CNES - Toulouse

- User survey in France and some european countries(PhD of Puissant, 2003)

- User survey in Belgium (SPIDER Poject)by Stephenne, Kanters, Wolff, 2004

Users Application Data scale Accuracy (m)

Input information Output document

Technicians(operational use)

technical management(level 1)

1:200 to 1:500

0.001 to 0.02 ground survey, measurements and large scale aerial photos

technical networks, topographic maps, …

basic town mapping (level 2)

1:1000 to 1:2000

0.02 to 1 ground survey and aerial photos

management and planning maps

Planners (tactical use)

town planning(level 3)

1:5000 to 1:10000

more than 1

existing maps, aerial photos

maps on LULC, master or structure plans, risks and hazards

Decision -makers (strategic use)

regional planning and communication (level 4)

1:25000 and less

more than 1

existing maps, aerial photos

structure plans, overview

End-user’s needs for image data


� Urban vegetation for urban planning and management

⇒ Important social dimension of « green » in a city

⇒ Minimal surfaces: very small areas !

• > 400 sqm in the city center

• > 2 500 sqm outside the city center

⇒ Legend : very diverse object types and not always green !

⇒ Solution in 1996 (Brussels ), in Strasbourg (actual database) :

• visual interpretation of aerial photos

• intensive fieldwork

End-user’s needs in ‘green’ data


Forest

Green spaces

Wooded element

Sportground

Family garden

Orthophoto, (c) IGN

End-user’s needs in ‘green’ data


‘Green’ in remote sensing

� Biophysical information from multispectral images

20 m 10 m

20 m 10 m

(c) Digital Globe

(c) CNES


‘Green’ in remote sensing

� Biophysical information from multispectral images

20 m 10 m

2.4 m 60 cm


Applications with VHR images

� Inventory of ‘green’ areas (detection)

� Inventory of vegetation types = green strata

=> wooded elements = ‘ecological corridors’

� Inventory of species

� Inventory of ‘green’ patterns

� Multi-temporal analysis

… by automatic or semi-automatic methods



� Inventory of ‘green’ areas

• Any vegetation : trees, shrubs, grass, gardens, agricultural areas, …

• NDVI = best vegetation index in Northern European context among NDVI, NIR/R, ARVI, SAVI and GEMI - Specific processing for bare-soils and agricultural crops

• OBIA classification on Quickbird images

Classes Confusion errors

Omission errors

Overall accuracy

BrusselsNon-Green

0.4 6.295.5

Green 12 0.8

GhentNon-Green

3.5 11.392.3

Green 11.7 3.7

Services for Urban Green Monitoring using Remote Sensing (SUGRES) (C. Baltus, E. Wolff – ULB and Tom Op 't Eyndt - GIM)



� Inventory of main vegetation types = ‘green’ strata


• Green strata = wooded elements, herbaceous, mixed vegetation

• Numeric detection of these objects requires high level parameters of interpretation (OBIA classification – rules based classification)

• Complementary information between 2.4m and 0.6m


� Inventory of ‘green’ strata => only with VHR imagery

0.6 m2.4 m

Wooded elementsIn the city center



COSTELUMR 6554 CNRS

Ecological corridors

2001 (Quickbird)

Lefebvre, 2011

� Inventory of ‘green’ strata => only with VHR imagery

In periurban areas


� CASI Image - September 2005, 32 bands� Spectral range 429-954 nm (bandwidth ~11.6 nm)� Spatial resolution 2 m

Feature extraction

Supervised classification

Dimensionality reduction

Hyperspectral image

Strata, species = input data for model

Vegetation mask

Vegetation index

� Inventory of species => only with hyperspectral imagery


Wania, 2007



=> complementary of HR and VHR imagery

• Wooded elements extracted with OBIA classification on SPOT (SVM algorithm) + spatial analysis (area and shape criteria)

=> different size and shape of green patches


Spot5 – 10 m

Forest

Boqueteaux

Bosquets

Continuity

Zhang, 2011

Periurban areas :


Applications with images

SPOT 5 – 10 m Quickbird – 2.4 m

Orthophoto


=> Complementary of HR and VHR images

Zhang, 2011



=> complementary of HR and VHR imagery

Rural areas(IFN classes)

Urban areas –Wooded elements (without agricultural areas, wasteland, etc)

4 thematic classes 10m – 4 cl. 2.4 m – 5cl

1. Forest : > 4ha

2. Boqueteaux: [0.5 – 4ha[3. Bosquets: [0.05 to 0.5[

4. Hedge row :

(L>25m et W > 20m)

1. Forest : > 5ha4. Boqueteaux: [0.5 to 5ha[5. Bosquets: < 5ha

6. Linear trees: L/W > 2

1. Forest: > 5ha

4. Boqueteaux: [0.5 to 5ha[5. Bosquets: < 5ha+ Individual trees (only with 0.6m)



Panchromatic image of 2000

Panchromatic image of 2003

Multitemporal color composite

Change detection

« Green => Non-green »« Non-green => Green »

0 10050Meters

� Detecting vegetation changesMultitemporal color composition (visualisation)Object oriented image analysis (interpretation)



�Multi-temporal analysis

• Acquisition of good quality images (haze and clouds) is hindered by the commercial distribution strategy



�Multi-temporal analysis

• Acquisition of good quality images (haze and clouds) is hindered by the commercial distribution strategy

• Suppose an orthorectification with a very detailed DTM

• 138 GCP located with:

- Topographic data at 1 : 10 000 (built-up) for the Brussels region

- orthophotos outside the region

• RMS (1.94 in X and 1.49 in Y)

No discrepancy Discrepancy



Conclusions ans perspectives

� Opportunity of Pleiades images

• Thematic and geometric precision

• Complemetarity with SPOT Series

• Reactivity, agility of the satellite

• Cover high surface

� VHR images useful to define a part of the ‘Green

Infrastructure’ defined by Grenelle II

� Green patches analysis by spatial indicators using by

landscape ecology (continuity, fragmentation)


Thanks for your attention

� Next Events :

‘Approches méthodologiques en géomatique pour la cartographie de la Trame Verte et Bleue’ (Workshop organised by GDR Magis – 24 janvier 2012 – Paris)

http://magis.ecole-navale.fr/

� Research projects

- Trame Verte (ANR Ville Durable 2009-2012 – Ph. Clergeau)

- VALI-URB (StereoII BELSPO/CNES – E. Wolff, L. Hubert-Moy, A. Puissant )

Pleiades Images – 2012 /12 /20

costel umr 6554 cnrs gt3 : vegetation in the city: the ... · pdf filepléiades days...

Documents