comparing directional maps

18
Rahul Rakshit Rahul Rakshit PhD Candidate PhD Candidate Clark University Clark University [email protected] [email protected] 1

Upload: rahul-rakshit

Post on 16-Jan-2015

496 views

Category:

Technology


1 download

DESCRIPTION

Presented in AAG 2008. Boston

TRANSCRIPT

Page 1: Comparing directional maps

Rahul RakshitRahul RakshitPhD CandidatePhD CandidateClark UniversityClark [email protected]@clarku.edu

1

Page 2: Comparing directional maps

Major PointsMajor Points

2

Page 3: Comparing directional maps

3

Page 4: Comparing directional maps

http://weather.gfc.state.ga.us/Maps 4

Page 5: Comparing directional maps

http://ipf.ov.ingv.it/MorphoVesuvio_file/Gallery/Ves_Gallery.htm 5

Page 6: Comparing directional maps

Location: Plum Island EcosystemsLocation: Plum Island Ecosystems

6Long Term Ecological Research (LTER) siteLong Term Ecological Research (LTER) site

Page 7: Comparing directional maps

7

Page 8: Comparing directional maps

8

Queen’s Case

Rooks' Case

Page 9: Comparing directional maps

ArcGIS Aspect Values (Degrees)

Idris

i Asp

ect V

alue

s (D

egre

es)

Scatterplot: Resolution 30 mScatterplot: Resolution 30 m

9

Page 10: Comparing directional maps

Issue in comparing directionsIssue in comparing directionsAspect is a circular variableAspect is a circular variable

All the Units are in DegreesAll the Units are in DegreesAll the Units are in DegreesAll the Units are in Degrees

360

90

180

270

5355

10

350

10

Page 11: Comparing directional maps

Direction

0

270

90

225

Direction

37

FineResolution

CoarseResolution

Magnitude

5Magnitude

6

2

7

2√2

2North

6

2√2

5resultant

37˚

7

Vector Addition: To coarsen the resolutionVector Addition: To coarsen the resolution

11

Page 12: Comparing directional maps

12

:9000

:9000

Page 13: Comparing directional maps

13

Coarse Resolution Aspect Maps After Vector AdditionCoarse Resolution Aspect Maps After Vector Addition

Page 14: Comparing directional maps

Scatter Plots: X Axis ArcGIS – Y Axis IdrisiScatter Plots: X Axis ArcGIS – Y Axis Idrisi

14

Page 15: Comparing directional maps

Resolution (m)

MAE

(Deg

rees

)Mean Absolute Error (MAE)Mean Absolute Error (MAE)Shows the average difference in directionShows the average difference in direction

15

CoarseFine

n

iii yf

nMAE

1

1

MAE is the weighted average of absolute errors

Page 16: Comparing directional maps

Major PointsMajor Points

16

Page 17: Comparing directional maps

For more information, please contact at : [email protected]

To tackle other types of variables, read the following from www.clarku.edu/~rpontius:

– Pontius, Thontteh and Chen. 2006. Components of information for multiple resolution comparison between maps that share a real variable. Environmental and Ecological Statistics.

– Pontius and Cheuk. 2006. A generalized cross-tabulation matrix to compare soft-classified maps at multiple resolutions. International Journal of Geographical Information Science.

Rahul extends special thanks to: Prof. Robert Gilmore Pontius Jr. for the concept and advice in every step of this research.

Acknowledgements and Plugs Acknowledgements and Plugs

17

Page 18: Comparing directional maps

18

CosSlope

SinSlope

*

*

tan 1

Aspect ArcGIS (Radians) Aspect Idrisi (Radians)

Cos (Aspect)Sin (Aspect) Cos (aspect)Sin (Aspect)

Slope (ArcGIS)

Slope * Sin Slope * Cos

Aggregate to coarser resolution

Vector Addition (ArcGIS)

Slope (Idrisi)

Slope * Sin Slope * Cos

Aggregate to coarser resolution

Vector Addition (Idrisi)

Scatter Plots at Coarser Resolutions

Study Area Mask

Mean Absolute Error (MAE)

Elevation

Coarse Angle(ArcGIS) Coarse Angle(Idrisi)

Coarse Angle Difference