Forest Mapping with VEGETATION

1
European Forest Map Prototype with VEGETATION
Work carried out by SCOT and KUL presented at
VEGETATION 2000 Conference with the support of
CNES and contribution of JRC and VTT
2
Objectives of the study

• Assessment of the capabilities of VEGETATION for
  mapping forest at regional scale
• Preparation of a European forest map prototype
• with simple methods applied to standard VGT
  products (10 days composites S10)

• Partners
• JRC methodology as developed for FMERS study
• KUL alternative approach for stratification
• SCOT processing
• VTT clustering method

3
Processing steps

• Data 21 composites S10 from April 1999 to
  October 1999
• Other data CORINE LC, JRC/FIRS stratification
  of European forest ecosystems

4
Processing steps

• Quality of VEGETATION S10 data

• High visual quality

• However
• problems of SWIR sensors
• cloud mask to be improved
• remaining directional effects

5

• S10 decade 2
• October 1999
• NIR/SWIR/R

6

• S10 decade 2
• October 1999
• NIR/SWIR/R

7
Processing steps

• Mapping procedure

• Stratification
• utilisation of FIRS strata
• alternative using landscape criteria
• Spectral clustering
• Selection of the most appropriate S10 for forest
  types discrimination and generation of a
  multi-spectral monthly composite
• Stratified clustering of the monthly composite
• Multi-temporal analysis of NDVI forest types

8
Stratification
Two alternative location of cluster means in
three ecosystem regions. A - means similarly
distributed - no likely need for pre-clustering
stratification. B - cluster means on the average
different in different regions - a likely need
for pre-clustering stratification.
9
Stratification
FIRS stratification superimposed over VGT S10
2 October 1999
10
Stratification
FIRS main regions after regrouping of main strata
11
Stratification

• Stratification alternative using landscape
  criteria

• fragmentation patterns, e.g. Shannon index...
• proportion of main land cover categories

12
Spectral clustering

• Generation of a monthly composite
• remaining clouds in all S10 products
• selection of three S10 composites
• D3 August 1999
• D1 September 1999
• D2 September 1999
• averaging procedure with elimination of bad
  pixels in the SWIR band and remaining cloudy
  pixels

13
Spectral clustering

• Generation of a monthly composite

10 days composite 3 August 1999
monthly composite (3 Aug / 1 2 September
1999)
14
Spectral clustering
15
Clustering

• Unsupervised clustering within each stratum into
  50 classes
• algorithm developed by VTT (Finland) and tested
  in the framework of FMERS for European forest
  mapping with IRS-WiFS data
• based on homogeneous signatures within 2x2 pixels
• automatic sort of the clusters according to their
  approximate biomass values

16
Clustering
Likely location of the target classes in the
spectral range (FMERS/VTT)
17
Clustering results

• Unsupervised clustering within each stratum into
  50 classes

15
20
18
Clustering results
19
Results

• contribution of the SWIR band

20
Results

• NDVI temporal profiles
• definition of temporal indicators

• distinction of three seasons for better
  discrimination of NDVI profiles related to forest
  types

• application to the 21 S10 composites

21
Colour composite NDVI three seasons
22
Results

• Temporal profiles of main forest cover types

23
Results

• Temporal profiles of other land cover types

24
Results

• Temporal profiles of CORINE classes

• Quality of CORINE classes ?
• Variability of vegetation phenology within broad
  land cover classes

25
Prototype of a European Forest Map derived
from VEGETATION data
26
CONCLUSIONS

• VEGETATION S10 products of very good quality
  geometry, radiometry
• but some improvements are still needed
  correction of directional effects, cloud masking
• the spectral clustering approach is leading to
  promising results with simple methods and a few
  S10 products
• dramatic potential of NDVI temporal profiles for
  discriminating vegetation types combination
  with spectral clustering ?
• need to improve and develop new standard products
  on NDVI profiles, e.g. phenology,
• products on land cover changes