The Modeler

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The Modeler
Why Bother??
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Because

• It is a record of what you have done
• And because of that it is easier to debug what
  you did because
• You wont remember exactly what you did unless
  you keep a notebook and write down everything you
  do including file names
• And you have to put a description of what you did
  in your report

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And

• If you get a job that requires GIS you damn well
  better be able to describe what you did
• Many firms/govt institutions/NGOs require that
  you keep notebook or other documentation because
  you can never tell when you will have to testify
  in court!
• And neither you or your company wants you to
  appear as a dim witted bozo who has no idea how
  you did your work several months/years ago.

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How does it work

• If you look in help you will see that almost
  every module/function has a command line
  equivalent in IDRISI's macro language

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2
3
4
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e.g., "area x acz12aczarea"
AREA command
1 x (to indicate that macro mode is being used)
2 input file name (image to use for area
calculation) 3 output format
(1image / 2values file / 3tabular)
4 unit type (unit of measurement for
output calculation 5 output file name (name
for resulting file)
1 cells 2 hectares 3 acres 4 sq. meters 5
sq. feet 6 sq. km 7 sq. miles
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The GUI Modeler

• Builds a series of Macro commands from the images
  you put in it and the connections you make
• So in some cases you have to get the order of
  images correct
• And provide the paths to other files like Reclass
  files
• When you click Run it goes ahead and executes
  each macro command in the order you specified.
• COOL

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Best Practices

• When ever you add an image check that it is what
  you think it is
• Run the model after adding any modules or
  changing any images
• When it works rename the output file to something
  that will mean something to you later
• Criteria 1, Area_Crit_1, LUxCrit1

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More

• Save often!
• The modeler can get screwed up!
• So save a series
• First version Criteria_1
• Second version Critera_2
• Etc.
• Why bother - you dont want to go through the
  model building again

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More yet

• Word will drive you nuts when you add images to
  a page
• So use PowerPoint as a drawing program
• Because you need to add info like
• Shorthand for RECLASSes
• X, etc. for OVERLAY
• Use multiply, add etc.., to get rid of that chore
• When you get the graphic the way you want it THEN
  group it and stick it in word.
• You can put your maps into word sideways by
  making the page for the map a section and make it
  layout

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Examples

• In one case the model refused to compute area of
  LUs correctly
• All input images were correct
• As were intermediate images
• Final was garbage
• In this case we
• Deleted the final steps
• Ran the model to insure it was working correctly
• Saved the model as xxx1
• Closed it
• Opened it again and checked that it was running
  ok
• Saved as xxx2
• Added the final steps again and it worked!

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How to go about it

• Consider the current problem where you are to
  find the area of landuses that remain after
  applying a series of more restrictive
  requirements
• Have to work with
• Slope
• Buffered water
• Elevation
• Etc.
• So

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Outline of Procedure

• Make a model for each criteria
• Slopes less than 15
• Water buffer
• Elevationgt900
• Etc.
• Now make a model that
• Combines (X) waterbuff and slope criteria1
• Compute LU Area
• Combine criteria1 and elevation criteria12
• And so on

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OUTLINE OF MODEL
oneA
AND
c1
oneB
Two
AND
c12
Three
AND
c123
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THEN DO THE AREA THING
oneA
AND
c1
Ac1
oneB
Two
AND
c12
Ac12
Three
AND
c123
Ac123
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Plan the output
oneA
img1
AND
c1
Ac1
val1
oneB
img12
Two
AND
c12
Ac12
val12
Three
AND
c123
Ac123
img123
val123
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Model for area files
Areatest computes both the area img and the val
files
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Areatest AND