9/9/97 - 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 colo90.v0.1.tar.Z. - 9/16/97

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The .tar file will uncompress to 91.4 Meg.  If you are operating on a 
Unix system type:
prompt: uncompress colo90.v0.1.tar.Z
Winzip should be able to uncompress this file also.

To expand the .tar file type:
prompt: tar -xvf colo90.v0.1.tar

This will create an ESRI 'info' directory and a 'grid' directory where
the .tar file resides.  These directories will use up  ~91 Meg 
in addition to the 91.4 Meg occupied by the .tar file.

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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 30 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 main classes are:

Class 1  Forest:

	Forest refers to primarily closed canopy humid tropical forest, and 
	includes cloud forest.

Class 2 Deforestation (80s epochs only.):

	Deforestation for the 90s will be calculated by comparing differences
	in the forest cover between epochs.
  
	Deforestation refers to areas of obvious human activity such as roads, 
	cities, farms/ranches, and any other areas where forest coverage has 
	been compromised.
 
Class 3 Revegetation (80s epochs only.):

	Revegetation for the 90s will be calculated by comparing differences
	in the forest cover between epochs.

	Revegetation refers to areas where imagery indicates the presence 
	of some type of vegetation that appears to be encroaching upon areas 
	of human activity.  These could indicate fallow fields, active 
	agriculture, tree plantations, or secondary regrowth.

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 7: Undifferentiated Unforested:

	Undifferentiated Unforested areas may have been forest at one time, 
	but were possibly deforested before the first data set reviewed by 
	the NASA Landsat Pathfinder Humid Tropical Forest Inventory Project 
	(i.e. pre-1972).  These areas also include  vegetation that may have 
	a different spectral signature than areas considered to be forest, 
	and require ground verification.
 
Class 8: Degraded Forest: (AFRICA ONLY)

	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. 

Class 21:  Questionable forest:

	Small areas, primarily in mountianous regions, that we believe are
	forest according to our definition but we need field validation
	to verify this.

Class 91: Gallery forest:

	Where Gallery forests are (1) mapped inconsistantly due to
	seasonality, image resolution (mss versus tm), and image quality
	and (2) the gallery forests are not contigious with the main
	forest, we have mapped them seperately.  

Class 92: Gallery deforestation:

	Deforestation that is happening within the gallery forests.

Class 93: Gallery revegetation:

	Revegetation that is happening within the gallery forests.

Class 1xx: Forest under cloud:

	These areas  are under cloud in the current epoch imagery,
	but by using additional later date scenes (the xx) we have
	verified that they are forest.  For example, class 194 in the
	80s coverage is cloud in the 80s image but has been verified
 	as forest in  a 1994 image.  We only classify cloudy regions
	as 1xx if we can verify in the later imagery that they have
	not been deforested.

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.


 
        *****Projection Information*****
 
Projection: Sinusoidal
Units : meters
 
longitude of central meridian is -60 00 00
false easting is 3000000 M
false northing is 3000000 M