The satellite image composite of continental Southeast Asia was produced from satellite data acquired by the VEGETATION sensor (VGT) on board the SPOT4 satellite. In four spectral bands and at a spatial resolution of about one square kilometre (112º -1) the sensor provides an almost daily coverage of the whole region (88ºE - 111ºE, 5ºN -30ºN).
All VGT 10-day standard composites from the two dry seasons 1998/1999 and 1999/2000 (end of December - end of March) were utilized for generating a cloud-free ‘regional’ image composite.
Image composition consisted of the: (i) the elimination of pixels affected by clouds, haze and sensor errors from the S10 composites (empirically defined thresholds in the blue band >10% and in the short wave infrared (SWIR) band <5% of reflection factor), (ii) the generation of monthly image composites (pixel selection by the minimum SWIR value), (iii) the generation of a ‘seasonal’ composite for each dry season with a pixel selection by the minimum value in the near infrared (NIR) band, and (iv) the combination of the seasonal composites to the final satellite image composite.
The composite is displayed in natural false colour, where the Red/Green/Blue components correspond to the VGT spectral bands SWIR/NIR/ Red. During the dry season this band combination discriminates well evergreen and seasonal vegetation. Evergreen forests are displayed in dark green (mangrove forests in blue-green), other green vegetation in light green. Broadleaved deciduous forests and shrubs appear brownish-violet during the dry season. Dry agricultural areas (upland crops) are displayed in colour tones from pink to orange-brown. Flooded and irrigated (temporarily flooded) agricultural areas (lowland crops) are represented by light bluish-green colours: rice cropping in the deltas of Ganges, Irrawaddy, Chao Praya, Red River and Mekong)
For more information on this topic, please contact Hans-Jürgen Stibig>
A new forest cover map of continental Southeast Asia derived from satellite imagery of coarse spatial resolution, Stibig, H-J., Achard, F. and S. Fritz, 2004. Applied Vegetation Science. 7: 153-162.
Forest cover map of Continental Southeast Asia at 1:4 000 000 derived from SPOT4-VEGETATION satellite images, Stibig, H-J. and Beuchle, R. 2003, Publications of the European Communities, EUR 20856 EN, 30 pp.