1/8/98 - This readme files contains information about the following Humid Tropical Deforestation Project coverages that can be downloaded from our website: http://www.geog.umd.edu/tropical/main.html: This README file pertains to the file drc90v02.tar.Z. - 9/13/00 Updates since Version 0.1 ------------------------- 9/23/97 - Optimized for non-cloud classes in overlapping regions between scenes Version 0.2 08/29/00 - Holes in data set have been filled using improved methods and new data. These improvements have allowed for better registration of the images, greater accuracy in the classification and improved consistency. These improved methods will be applied to all images in the study area as time and funding permits. The year that each image used was acquired is now included as an item in the grid. (see bottom of this file for format) >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The .tar file will uncompress to 66.2 Meg. If you are operating on a Unix system type: prompt: gunzip drc90v02.tar.Z To expand the .tar file type: prompt: tar -xvf drc90v02.tar This will create an ESRI 'info' directory and a 'grid' directory where the .tar file resides. These directories will use up ~64 Meg in addition to the 66.2 Meg occupied by the .tar file. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Country coverages are being placed on the website as they are being finished. It is important to note that these are preliminary products. Field checking has been carried out in some areas, but is not complete. It is anticipated that revisions to this product will be progressively incorporated. Revisions will have higher version numbers. Details about the specific improvements in each version will be available as new versions are released. This ARC/INFO grid has a pixel size of 57 meters to a side. The output projection is Sinusoidal. An ARC 'describe' will list the relevent projection information, it is also included at the bottom of this file. The forest cover classes are under item VEG_CLASS in the .vat The main classes are: Class 1 Forest: Forest refers to primarily closed canopy humid tropical forest, and includes cloud forest. Class 4 Water: Water includes lakes, rivers, and oceans if applicable. Water also includes areas that are inundated by dam/reservoir projects. Swamps may also appear as water. Class 5 Cloud: Cloud refers to areas where ground data is obscured or altered by cloud. Class 6: Shadow Shadow can be caused by either terrain or clouds. Class 9: Nonforest: Nonforest includes areas such as cerrado, savanna, rock outcrops, high elevation brush/scrub vegetation, sand dunes or spits/bars, predominantly deciduous seasonal forest, snow fields, heavily inundated flood plains with sparse vegetation. Currently this class also include areas of agriculture and forest that has been partially degraded through selective logging or agriculture as well as regenerating forests. Degraded/regenerating forests will be split into a separate class in later versions. Class 999/0: These are no-data pixels where there was not good, cloud free imagery available. As we continue to search and obtain replacement data, future versions of the coverages will have areas of 999 replaced by the correct vegetation class. Areas of 0 are poor quality subareas within an image where we were unable to confidently determine the vegetation type. *****Items in the .VAT***** ARC> items DRC90oputv02.vat COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? 1 VALUE 4 10 B - - 5 COUNT 4 10 B - - 9 DRC90DATE 4 16 B - - 13 VEG_CLASS 4 16 B - - VEG_CLASS corresponds to the definitions listed above. DRC90DATE is the year that pixel data was acquired. *****Projection Information***** The Central African Republic grids are in sinusoidal projection with: longitude of central meridian is 20 00 00 false easting is 3000000 M false northing is 3000000 M