[UW-GIS-L] Projections and FRAGSTATS

[Phil Hurvitz]

Without knowing details it is difficult to determine what the problem 
might be. Generally projection problems in Arc come from the difference 
between "native" coordinates (i.e., the actual XY values stored on the 
features at a low level; these are typically hidden from the user) and 
"defined" coordinates (which can be altered in the definition or .prj 
file. The defined coordinate system should match the native coordinate 
system or ArcMap will give you problems.

One way to test what's up is to add your data sets and then clear the 
projection on the data frame. If the data sets share the same coordsys 
they should line up. If not, then they don't have the same native 
coordinates.

See

http://gis.washington.edu/phurvitz/gis_data/projection_exercise/

for an exercise in projections, and some data sets that might be useful:

http://gis.washington.edu/phurvitz/gis_data/projection_checker/

-P.

  **************************************************************
      Phil Hurvitz, MFR | PhD Student, Urban Planning | CBE
          1107 NE 45th Street, Suite 535 | Box 354802
  University of Washington, Seattle, Washington  98195-4802, USA
  phurvitz at u.washington.edu | http://gis.washington.edu/phurvitz
  "What is essential is invisible to the eye." -de Saint-Exupéry
  **************************************************************


Jorge Ramos wrote:

> Basic question about projections that I would have not sent out but 

> since I have been attempting the same thing for quite a long time now 

> here it goes.

> 

> I used a grid (Defined Projection of NAD_1983_Albers) to run some 

> FRAGSTATS analysis. The outputs are three grids with undefined 

> projections. I add them to a new Arc Map data frame but even after I 

> define their projections to NAD_1983_Albers and Project Raster 

> to NAD_1983_Albers they dont match with the original GRID and other 

> feature layers. 

> 

> Am I skipping a step here or is it that FRAGSTATS's outputs did not keep 

> their original coordinate systems? If that is the case does someone know 

> how to create FRAGSTATS outputs that keep their original coordinate system?

> 

> Any advice will help.

> 

> Thanks,

> 

> Jorge

> 

> 

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