Distance Surface

Screenshot

File:DistanceSurface.gif

Download Model

Download the .scn, .sel and .lse files by clicking on the following link: File:DistanceSurface.zip

Model Code Exploration

In the following sections we will examine all of the model files for this model. Note that instead of downloading the zip file above, you could just copy the text in the boxes below into a text editor and save it with the appropriate name (Section title). Opening the resulting .scn file in the SELES simulator would run this model.

Dist2Roads.scn

SELES Scenario
$gisData$ = ..\..\CaseStudy\gisData\cell
StudyArea = $gisData$\StudyArea
SrcLayer = $gisData$\roads
Model Dimensions: StudyArea 
Model.sel
SimPriority Low Priority
SimStart 100000 1

Dist2Streams.scn

SELES Scenario
$gisData$ = ..\..\CaseStudy\gisData\cell
StudyArea = $gisData$\StudyArea
SrcLayer = $gisData$\water
Model Dimensions: StudyArea 
Model.sel
SimPriority Low Priority
SimStart 100000 1

Model.lse

Seles Model
Landscape Events:
  Distance.lse DEBUG
Spatial Constants:
  StudyArea
  SrcLayer
Global Constants:
 CellWidth = CELL WIDTH(StudyArea)
Spatial Variables:
  DistanceFromSrc[CellWidth*(NumRows^2 + NumCols^2)^0.5 + 1] <= 0
  NearestSrcLoc[-1] <= 0

Distance.lse

LSEVENT: DistanceSurface
DEFINITIONS
 LAYER: StudyArea, SrcLayer
 LAYER: DistanceFromSrc, NearestSrcLoc
 GLOBAL CONSTANT: CellWidth
 CLUSTER VARIABLE: StartLocation
 CELL VARIABLE: distInc, d
ENDDEF
INITIALSTATE
  OVER REGION WHOLE MAP
     DECISION (StudyArea > 0)
     DistanceFromSrc = CellWidth*(NUMROWS^2 + NUMCOLS^2)^0.5 + 1
  ENDFN
//   DistanceFromSrc = IF (StudyArea > 0) THEN CellWidth*DISTANCE(LOCATION(0,0),   LOCATION(NUMROWS-1, NUMCOLS-1)) ELSE 0
  INITIALSTATE = 1
ENDIS
RETURNTIME = 0
EVENTLOCATION
  REGION WHOLE MAP
     DECISION (StudyArea > 0) AND (SrcLayer > 0)
ENDEL
PROBINIT
 PROBINIT = 1
 StartLocation = Location
 distInc = 0
 d = 0
ENDPI
TRANSITIONS
 TRANSITIONS = (d < DistanceFromSrc)
 DistanceFromSrc = d
 NearestSrcLoc = StartLocation
ENDTR
SPREADTIME = distInc
// Spread to the four cardinal neighbours
SPREADLOCATION
  REGION CENTRED(1, 1)
     DECISION (StudyArea > 0) AND (SrcLayer <= 0) AND (DistanceFromSrc > (CellWidth *  DISTANCE(StartLocation, Location)))
ENDSL
SPREADPROB
  SPREADPROB = 1
  d = ROUND(CellWidth*DISTANCE(StartLocation, Location))
  distInc = MAX(0,d - SOURCE d)
ENDSP

Suggested Experiments

To explore this cellular automata model further, try the following: