1. Modeling Space/Time Variability with BMEGUI
Prahlad Jat(1) and Marc Serre(1)
(1) University of North Carolina at Chapel Hill

2. Agenda
Introduction
Mean Trend Analysis
Space/Time Covariance Analysis

3. Introduction

4. Temporal GIS analysis process
Read Data File
Data Field Screen
Check Data Distribution
Data Distribution Screen
Exploratory Data Analysis Screen
Exploratory Data Analysis
Mean Trend Analysis Screen
Mean Trend Analysis
Space/Time Covariance Analysis Screen
Covariance Analysis
BME Analysis
BME Estimation Screen

5. Mean Trend Analysis Screen
Display temporal mean trend
Display spatial mean trend (Raw & Smooth)
Model Parameter (Exponential Smoothing)

6. Space/Time Covariance Analysis Screen
Display spatial & temporal covariance
Plot covariance models

7. Mean Trend Analysis

8. Mean Trend Calculation
Assume a separable additive space/time mean trend model
Input Parameter
Spatial Radius/Spatial Range
Temporal Radius/Temporal Range
Averaging the measurement at each MS (or at each time point)
Find measurements within “Radius” , then apply exponential filter

9. Smoothed Mean Trend
Sradius
Tradius

10. Z - (SSM+STM-mean(STM))
Remove Mean Trend
Removing the mean trend from data
Z - (SSM+STM-mean(STM))
Z: Value
SSM: Smoothed Spatial Mean Trend
STM: Smoothed Temporal Mean Trend

11. Calculate Mean Trend Click “Model mean trend and remove it from data”
BMEGUI automatically calculate mean trend using the default parameters

12. Temporal Mean Trend Raw Temporal Mean Trend is shown in dotted line
Smoothed Temporal Mean Trend in shown in solid line
Zoom in/out

13. Spatial Mean Trend Two tabs – Spatial Mean Trend (Raw)
Spatial Mean Trend (Smoothed)
Zoom in/out
Point Layer File

14. Recalculate Mean Trend
Input parameters and click “Recalculate Mean Trend” button
Spatial Radius/Spatial Range
Temporal Radius/Temporal Range
Spatial Range
Spatial Radius
Click Button
Temporal Radius
Temporal Range

15. Space/Time Covariance Analysis

16. Space/Time Covariance Analysis
Experimental Covariance (Red dots)
Fit experimental covariance with covariance model (Solid Line)

17. Spatial/Temporal Components
Two tabs
Spatial Component
Temporal Component
Temporal Component Tab
Spatial Component Tab

18. Experimental Covariance
BMEGUI automatically calculate experimental covariance using the default lag setting
User can modify the lag setting
Change the number of lags
Input user-defined lag and lag tolerance

19. Change number of lags
Input the number of lags, then click “Recalculate Spatial/Temporal Covariance” button
Recalculate
Spatial Cov.
Number of lags for Spatial Cov.
Recalculate
Temporal Cov.
Number of lags for Temporal Cov.

20. Modify lag and lag tolerance
Click “Edit Spatial/Temporal Lags…”
Input lag and tolerance in dialog box, then click “OK” (Use “,” to separate the values)

21. Covariance Model BMEGUI supports
homogeneous/stationary Space/Time random field
Space/Time separable model
Maximum four model structures
Following covariance model
exponential
gaussian
spherical
holecos
holesin

22. Set the number of model structures
Input the number into text box (1-4)
The number of tabs will change

23. Select covariance model
Select model from the combo box
Input sill and range, then click “Plot Model”

24. Clear covariance model
Plot “Clear Plot” button
Covariance model will be erased from the figures