aliens and geographic things: a GIScience perspective
Femke Reitsma
School of Geosciences, Edinburgh University e-Science Institute 23/07/2007

hmm.....
Randy Stevens – Cocktail Party

Randy Stevens – Cocktail Party

legs cocktail glasses heads

Randy Stevens – Dancers I, II, III

outline
1. standard GIS things
2. spatio-temporal things
3. qualitative challenges

observation → representation
●
●
● what should we abstract?
influences explanation first question = what do we want to explain?

standard GIS things
● the geo-atom < x Z z x
1
> point polygon line pixel

point

line

polygon

pixel http://landmap.mimas.ac.uk

data model implications borrowed from esri.com

time + standard GIS things
●
● snap shots change detection t1 t2 t3 t4 time

time + standard GIS things
●
●
Hägerstrand
Space-time path

static GIS due to...
• cartographic origins
• emphasis on attributes & relationships vs. process and change
• presumed priority of objects in human cognition

outline
1. standard GIS things
2. spatio-temporal things
3. qualitative challenges

spatio-temporal things: agents
● agent based modelling

ABM grazing simulation
Water sources
Agent-based animals
Borrowed from Conrad Rider

Even grazing pressure More pressure at water source
Borrowed from Conrad Rider

spatio-temporal things: processes
●
● represented in dynamic models as sets of equations or rules not represented as output www.answers.com
www.metoffice.gov.uk

process interpolation
●
● problem of multiple process pathways equifinality f(x) t1 t2 time

process interpolation t1 t2 time

process data model nen = (node,edge,node) nen = process

process data structure x1, y1 attributes x2, y2 spatial location
nen = (x1, y1, x2, y2, t, st, {a1, a2, …an}, {r1, r2, … rn}) temporal location spatio-temporal granularity rules

why?
• query processes
• analyze processes
• better understand model’s spatial behavior

outline
1. standard GIS things
2. spatio-temporal things
3. qualitative challenges

what can't we currently represent in a GIS?
●
● complex real-world stuff qualitative information image from http://www.corrwillbourn.com/

qualitative information
• can we reduce qualitative information?
• how do we represent it in a GIS?
• qualitative information models?
• first question = what do we want to explain?

qualitative information models?
• data models
• information models
• knowledge models
< x Z z x
1
>

semantic geospatial data models?
● richer data models → information models
< x Z z x
1
>
● how do we inject complexity into our data models?

back to our alien….

thank you