Commands for the Generation of all Data
Arc: describe denid
Description of Grid /JAZ/GIS/GISPROJ/DENID
(Tree density grid of the state of Idaho)
Cell Size = 1055.370 Data Type: Integer
Number of Rows = 807 Number of Values = 101
Number of Columns = 498 Attribute Data (bytes) = 8
BOUNDARY STATISTICS
Xmin = -1715207.625 Minimum Value = 0.000
Xmax = -1189633.270 Maximum Value = 100.000
Ymin = 2208308.250 Mean = 41.648
Ymax = 3059991.994 Standard Deviation = 33.483
COORDINATE SYSTEM DESCRIPTION
Projection ALBERS
Datum NAD83
Units METERS Spheroid GRS1980
Parameters:
1st standard parallel 29 30 0.000
2nd standard parallel 45 30 0.000
central meridian -96 0 0.000
latitude of projection's origin 23 0 0.000
Continue?
false easting (meters) 0.00000
false northing (meters) 0.00000
Arc:
Unzipping and
alpha62:mcadams:/jaz/gis/gisproj/DLG2M$ gunzip ID.trans.sdts.tar.gz
untarring
alpha62:mcadams:/jaz/gis/gisproj/DLG2M$ tar -xvf ID.trans.sdts.tar
Projecting a Cover or grid
Arc: project cover idroads idtrans_alb alb.prj
Creation of the slope grid:
Arc: grid
Copyright (C) 1982-1996 Environmental Systems Research Institute, Inc.
All rights reserved.
GRID Version 7.0.4 (Sun Jan 21 22:27:17 PST 1996)
Grid: idslope = slope ( demid )
Running... 100%
Grid: q
Now we need to make some changes in the current dlg - removing the
state border and some other spurious lines.
Arc: arcedit
Copyright (C) 1982-1996 Environmental Systems Research Institute, Inc.
All rights reserved.
ARCEDIT (COGO) Version 7.0.4 (Sun Jan 21 22:27:17 PST 1996)
Arcedit: edit idtrans_alb
The edit coverage is now /JAZ/GIS/GISPROJ/IDTRANS_ALB
Defaulting the map extent to the BND of /JAZ/GIS/GISPROJ/IDTRANS_ALB
Arcedit: display 9999
Arcedit: editfeature line
395 element(s) for edit feature LINE
Coverage has no COGO attributes
Arcedit: drawenvironment line on
Arcedit: mapextent idtrans_alb
Arcedit: display 9999
Arcedit: mapextent idtrans_alb
Arcedit: draw
Arcedit: select many *
1 = Select 2 = Next 3 = Who 9 = Quit
No match found
1 = Select 2 = Next 3 = Who 9 = Quit
Arc 373 User-ID: 373 with 361 points
1 = Select 2 = Next 3 = Who 9 = Quit
Arc 375 User-ID: 375 with 361 points
1 = Select 2 = Next 3 = Who 9 = Quit
Arc 374 User-ID: 374 with 281 points
1 = Select 2 = Next 3 = Who 9 = Quit
Arc 376 User-ID: 376 with 281 points
1 = Select 2 = Next 3 = Who 9 = Quit
Arc 381 User-ID: 381 with 5 points
1 = Select 2 = Next 3 = Who 9 = Quit
......... then when you are done...........
Arc 293 User-ID: 293 with 4 points
1 = Select 2 = Next 3 = Who 9 = Quit
41 element(s) now selected
Arcedit: delete
41 arc(s) deleted
Arcedit: save
Saving changes for /JAZ/GIS/GISPROJ/IDTRANS_ALB
Saving arcs...
354 arc attribute record(s) written to /JAZ/GIS/GISPROJ/IDTRANS_ALB
354 arc(s) written to /JAZ/GIS/GISPROJ/IDTRANS_ALB
from the original 395, 0 added and 41 deleted
Reopening arcs...
BND replaced into /JAZ/GIS/GISPROJ/IDTRANS_ALB
Re-establishing edit feature ARC
Arcedit: q
Leaving ARCEDIT...
Arc: build
Usage: BUILD (cover) {POLY | LINE | POINT | NODE | ANNO.(subclass)}
Arc: build IDTRANS_ALB
Building polygons...
Re-building AAT...
Arc:
making a grid from the Idaho boundry cover
Grid: usage polygrid
Usage: (*) POLYGRID((cover),{item},{lookup_table},{weight_table},{cellsize})
Grid: idbgrid = polygrid ( idalb , # , # , # , 1000 )
Converting polygons from IDALB to grid IDBGRID
Number of Rows = 852Grid:
Number of Columns = 526
Percentage of Gridded Cells...100%
Grid: gridpaint idbgrid
WARNING the Map extent is not defined
Grid: mape idbgrid
Grid: gridpaint idbgrid
see what the output looked like
idbgrid.gif
In order to chop the rest of the country off all the grids that look kinda like
this
we can perform a Bolean query
idaho_den = setnull ( not idbgrid , denid )
Running... 100%
Grid: gridpaint idaho_den
Graphic device not specified
Grid: display 9999
Grid: gridpaint idaho_den
and it has output that looks like this
idaho_den.xwd
we do this on all the grids ie: tree type, slope grid, etc.
Now I have to buffer the rivers and roads. This simulates the BMP exclusion
zones for trees. The zone is 25m on either side of a stream river or road.
Arc: buffer idtran_alb bufftran # # 25
Buffering ...
Sorting...
Intersecting...
Assembling polygons...
Creating new labels...
Finding inside polygons...
Dissolving...
Building nodes...
Creating bufftran.PAT...
Arc:
Arc: buffer rf1id buffriv # # 25
Buffering ...
Sorting...
Intersecting...
Assembling polygons...
Creating new labels...
Finding inside polygons...
Dissolving...
Building nodes...
Creating bufftran.PAT...
Arc:
Now we have to make a grid of the rivers and roads in order to exclude them
from the analysis area.
v
Grid: idaho_river = polygrid ( buffriv , # , # , # , 100 )
Converting polygons from BUFFRIV to grid IDAHO_RIVER
Number of Rows = 8471
Number of Columns = 5238
Percentage of Gridded Cells...100%
now the roads and rivers need to be buffered.
buffer
Arc: Usage: BUFFER (in_cover) (out_cover) {buffer_item} {buffer_table}
{buffer_distance} {fuzzy_tolerance} {LINE | POLY | POINT | NODE}
{ROUND | FLAT} {FULL | LEFT | RIGHT}
Arc: buffer roacoeur buffroad # # 50
buffering
Arc:
I then went and interpolated the forest density grid
Grid: resample
Usage: (*) RESAMPLE ((grid), {cellsize},
{NEAREST | BILINEAR | CUBIC | SEARCH})
Grid: resmden = resample ( smden , 100 , cubic )
Resample ... 100%
Grid:
Now let's just say for example that slopes above 30% are too steep to cut on.
These must be excluded from the analysis. We do this by using the steps below.
Grid: slope_remov = con ( couslope > 30 , 1 , 0 )
Running... 100%
Grid: con
Usage: (*) CON ((condition), (true_expression)
{, (condition), (true_expression)}...{, false_expression})
Grid:
Now we have to assemble a river and road removal grids.
Grid: polygrid
Usage: (*) POLYGRID((cover),{item},{lookup_table},{weight_table},{cellsize})
Grid: road_remov = polygrid ( buffroaD , # , # , # , 100 )
Converting polygons from BUFFROAD to grid ROAD_REMOV
Number of Rows = 277
Number of Columns = 219
Percentage of Gridded Cells...100%
Grid: riv_remov = polygrid ( buffriv , # , # , # , 100 )
Converting polygons from BUFFRIV to grid RIV_REMOV
Number of Rows = 309
Number of Columns = 202
Percentage of Gridded Cells...100%
Grid:
Now we can combine all three of the above removal grids and make one removal
grid.
We must make sure that both the river and road grids don't have any null values
or the resulting grid will have only values for common cells of all the grids.
So this is what we do to combat that problem.
Grid: con
Usage: (*) CON ((condition), (true_expression)
{, (condition), (true_expression)}...{, false_expression})
Grid: nriv_remov = con ( isnull ( riv_remov ) , 0 , riv_remov )
Running... 100%
Grid: nroad_remov = con ( isnull ( road_remov ) , 0 , road_remov )
Running... 100%
Now we can combine the three grids into a single removal grid.
Grid: addremov = nroad_remov + nriv_remov + /jaz/gis/gisproj/sdem/slope_remov
Running... 100%
Because we have a grid that has values for all the cells in the domain (even
though many have a value of 0) we must now go and remove the 0 values and
convert them to the null value, otherwise when we try to remove just the
buffered roads, rivers and steep slopes, all the cells in the foest density grid
will dissapear, ande we wouldn't want that to happen now would we!!! So we use
the commands below.
Grid: setnull
Usage: (*) SETNULL ((condition), {grid | scalar | number})
Grid: removal = setnull ( addremov == 0 , addremov )
Running... 100%
Because I don't give a flying f what the values of the grid are I decided to
make all of the values of the grid equal to one (basically so they look better
in arcview).
Grid: removal1 = removal / removal
Running... 100%
Now we need to intersect the removal1 grid with the forest density grid. With
the cells of the removal1 grid removed from the density grid I more or less
achieved my original goal of this study. Here are the commands.
Grid: removal2 = con ( isnull (removal1) , good_den , 0 )
Running... 100%
This next command takes the rivers, stream and slope values and makes them null.
Grid: removalden = setnull ( removal2 == 0 , removal2 )
Running... 100%
When I did the resample command a while back the grid created had values greater
than 100% coverage and because this can't physically happen I set all the grid
values that were greater than 100 to a value of 100. Here is the command.
Grid: removalden2 = con ( removalden (greater than sign - htm doesn't like them) 100 , 100 , removalden )
Running... 100%
Grid:
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(c) Copyright Mike McAdams, 1997
if you want something e-mail me at:
mcadams@mail.utexas.edu