Sunday, September 25, 2011

Satellite Photo Interpretations Agricultural Lands in Delta Region of Burma aftermath of Nargis Cyclone


In late 2008, I volunteered for Northwest GIS Response Team of Seattle, Washington State, USA, which was conducting a project digitizing paddy fields of delta region of lower Burma after devastated by Nargis Cyclone.  The team was to identify pre-damage wet rice agricultural production throughout the Ayarwaddy (Irrawaddy) delta area, requested by UNOSAT.  I assisted this team of 70 volunteers digitizing paddy fields on the satellite imageries posted on Google.  I made a series of slides with identification of features on the satellite images raised by the volunteers  I was aware that understanding the cultural background of man-made landscape of a place in a foreign country would be helpful.  Therefore, I attempted to provide some agri-‘cultural facts’ about the features they have located verifying my interpretation of the satellite photos.  I was fortunate to find Mr. Than Win of Fremont, California, USA, whose family and himself have lived and cultivated various crops in the paddy fields in the delta region.  He was my best ‘ground truthing’ of the features on the satellite photos.  Having conferred with Jim Ellis (Ellis-Geospatial of Walnut Creek, California, USA), my interpretations were verified.  Thanks to Glenn Brook, his technical team, and the volunteers for caring about Burma and the GIS efforts with Google and ArcGIS functions.  The team estimated that the cyclone affected area included more than 3,000,000 individual rice paddy plots and that the project was able to digitize 30,000 individual rice paddy's on line through the use of a custom developed on-line GIS editing tool.  The interpretive explanations allowed the creation of a visual training guide that identified many different rice paddy configurations and crop types visible on Google Earth.

Mosaic of Images

The mosaic imageries on Google Earth™, shown on this picture were of various regions of Burma’s Ayeyarwaddy delta.  The yellow dash-lines show the boundaries of scenes with different colors and tones.  Darker colors of the images could be misled in the interpretation of the same features as two different items.
Color Differences on Images

The sites below show various regions of the Burma’s Ayeyarwaddy delta.  Each photo shows the differences in color on the images posted on Google Earth™ (GE).  A general boundary line was drawn on each picture distinguishing the areas where two different photos merged in a mosaic.  The imageries posted on GE has been provided mostly by various satellite companies such as Digital Globe, GeoEye, TerraMetrics, Europa Technologies and Image NASA.  The differences in colors on images could be due to the differences in atmospheric conditions, the look angle between the different images, the contrast stretch used by the provider, and the pan sharpening algorithms.  (Dr. Jim Ellis of Ellis-Geospatial)  The color-balancing could be done for each scene and minimized the differences while mosaicking, but it will be costly.  The images made available on GE must have been used with readily available pan sharpened scenes with difference colors and tones.  Therefore, the users of these imageries on GE should be aware of color differences in identifying agricultural features during the digitizing exercises for Myanmar Paddy Project.  Especially, some features on the images could be misled by green, brown and dark colors.  The images were made in summer of 2008, however, the images could have taken on different months of summer.

Shapes and Patterns of Agricultural Lands 
  Agricultural Lands in Summer

  re-established and posted on September 25, 2011 by winnerscircle.

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