1/19/98 - 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/index.html: This README file pertains to the file drc80_16k_v02.e00.gz - 9/12/00 Updates since Version 0.1 ------------------------- 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 file drc80_16k_v02.e00.gz will uncompress to 2.5 Meg. If you are operating on a Unix system type: prompt: gunzip drc80_16K_v02.e00.gz To expand this file you will need to type the following at the Arc prompt; ARC: import grid drc80_16K_v02.e00 This will create an Arc/Info grid ~1.5 Megs in size. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 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 16 kilometers to a side. The output projection is Sinusoidal. An ARC 'describe' will list the relevant projection information, it is also included at the bottom of this file. The items within the .vat are defined below the class definitions. The 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 8: Degraded Forest: Degraded forest are areas in Africa where human activity is visible. Due to the landuse patterns, including selective logging, differentiation between deforestation/revegetation/agriculture is not currently possible. Generally discernible from natural forest, the true extent may only be determined through ground verification. 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. This class also includes areas of human activity that are maintained as open grassland/scrub. Class 21: Questionable forest: Small areas that we believe are forest according to our definition but we need field validation to verify this. Class 999/0: These are no data pixels where there was no 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. 16 KM Product: ---------------- The 80s epoch is being provided in a 16 KM(per grid cell side) resolution product. The 90s epoch data will be released in additional higher resolution formats. All percentages and area measurements are derived from the full resolution coverages. The file is the product of "export" from Arc/Info version 7.2.1 (copyright ESRI, Inc., Redlands, Ca). In order to display the .e00 file, you must first use Arc "import" to recreate the coverage. The usage is: Arc:import grid drc80_16K_v02.e00 Variables for each 16 km grid cell: Percent_1: The fraction of forest within the map cell. Percent_4: The fraction of water within the map cell. Percent_5: The fraction of cloud within the map cell. Percent_6: The fraction of shadow within the map cell. Percent_8: The fraction of apparent human disturbance. Percent_9: The fraction of non-forest within the map cell. Percent_999: The fraction of 999 in the map cell. 999 is 'Data not Available' The Percent_x values are not currently calculated as actual precentages of the cell but as decimal fractions of the whole. Multiply by 100 to get the percentage of the grid cell occupied by the class. Areas are calculated based on the pixel size (57 meters for 80s) and the number of pixels for a particular class within the map cell. Units are square meters. area_1: The area covered by humid tropical forest. area_4: The area occupied by water. area_5: The area obscured by cloud cover. area_6: The area of shaodw. area_8: The area of apparent human caused forest degradation. area_9: The area covered by non-forest vegetation. Area_999: The area of unavailable data *****Projection Information***** The grids are in sinusoidal projection with: longitude of central meridian is 20 00 00 false easting is 3000000 M false northing is 3000000 M