Download - Generation of a Digital Elevation Model using high resolution satellite images By Mr. Yottanut Paluang FoS: RS&GIS

Generation of a Digital Elevation Model using high resolution satellite images

By Mr. Yottanut Paluang

FoS: RS&GIS

Presentation Outline Presentation Outline

1.1. IntroductionIntroduction

2.2. MethodologyMethodology

3.3. Result of this studyResult of this study

4.4. ConclusionConclusion

IntroductionIntroduction•Digital elevation models (DEMs) are increasingly used for visual and mathematical analysis of topography, landscapes and landforms as well as modeling of surface processes.

•This study attempts to find out the quality assessment of DEM products using different satellite images including ASTER and ALOS PRISM stereo image, comparing existing DEM.

•Three techniques are used to validate the result of DEM products

ALOS PRISMASTER

DEM

Generation

Objectives

1. To fuse DEM from ASTER and ALOS PRISM satellite imagery.

2. To evaluate the derived DEM for the suitability in term of terrain surface application.

3. To verify the result of DEM for several terrain surface in term of application suitability.

Study Area

Map of the Study area

6




4.4. Conclusion Conclusion


7

Available data

Material Name Data DescriptionProducing or

Acquisition Remark

ASTER Image Pair

Level 1AVNIR Band 3 nadir and

backward views, spatial resolution 15 m

20050107(acquisition date)

The data source of this study

ALOS PRISM Image Pair

Level 1B2 nadir and backward

Spatial resolution 2.5 m

20071023(acquisition date)

Topographic map

Scale 1: 50,000, contour interval 20 m,

coordinate system: UTM /WGS 84

2001

-Used for collected data- gained from RTSD

8

Ground Truth The form of Ground truth for collecting data.

Date & Time: 14 November, 2007 Serial No. 53

Code of Point on Map: 670

Code of Point on image : 1

UTM/ WGS 84

GPS Coordinates Lat/Long

GPS Coordinates

497112 1906530 17º 14' 37.82″N 98º 58' 22.19″ E

GPS Altitude : 248 m Map Altitude : 240 m

No. of Satellites: 8

Description ( on the map) : The intersection of road and right edge of Bhumibhol Dam

Terrain type : Near the right edge of Bhumibhol Dam and medium terrain

Remark : This cross is clear on both map and image

Located on Ban Wang Khai – Song Khaw, Sam Ngao district , Map Sheet: 4843 III

9

Ground Truth Cont’dGround truth for collecting data.

10

Methodology

DEM Generation

Accuracy Assessment

Result

ASTER

ALOS PRISM

DEM ValidationDEM Validation

ASTER DEM

ALOS PRISM DEM

Fused DEM

+

• Locational Error

• Profile Curvature

• Check Points

• Mountain Area

• Flat Area

• Water Area

11

Methodology Cont’dObjective 1: To fuse DEM from ASTER & ALOS PRISM satellite images

ASTER DEM ALOS PRISM DEM

Fused DEM

GCPs Selection

Tie Points Selection

Triangulation

DEM Generation

ASTER Images

Ground Truth Data

ALOS PRISM Images

Data processing

12

USGS DEM

Elevation range

Low: 30 m

High : 1931 m

13

ASTER DEMASTER DEM

Elevation range

Low: 58 m

High : 1086 m

14

ALOS PRISM DEM

Elevation range

Low: 135 m

High : 1625m

15

Fused DEMFused DEM

Elevation range

Low: 58 m

High : 1086 m

16

Methodology Cont’d

Objective 2: To evaluate the derived DEM for suitability of terrain surface application

1. comparison of the drainage network from these DEM

17

Drainage networksDrainage networks

Referenced - USGSReferenced - ASTERReferenced - ALOSReferenced - FusionAll Drainage networksReferenced Data

18

Locational Error

• First step: line buffering. Perform a buffer operation on the line data sets X , using a buffer size, ε, which should be significantly larger than the geometric accuracy measure found for the data set X.

• Second step - overlay. Perform an overlay of the two line-polygon overlays: Overlay Xε with Q, resulting in the new mixed data sets as XεQ.

• Third step: statistics. Statistics is run to determine completeness

Length (Q inside Xε )Completeness (X ) = Length (Q)

19




2. comparison of the terrain relief and Profile Curvature

20

Terrain relief & Profile Curvature

- Linear error represents the accuracy of the vertical and the horizontal position.

- Differences of profile curvature between DEMs are displayed as linear features

Derived DEM Referenced DEM

Result

Comparison

21




2. comparison of the terrain relief and Profile Curvature

3. comparison of the elevation of the derived DEM with the check points

22

Comparison of the elevation of the derived DEM with the check points

• Defined from the GCPs, Tie points, and user define• An algorithm of accuracy evaluation called Root Mean Square

Error (RMSE)

Where mz is RMSE of elevation

δZi is the elevation differences between the derived DEM

and the check points n is the number of check points

mz = √ 1 δzi2

i=1

n

_n

∑

The lower the RMSE, the better the solution

23

The number of Check Points

Check points

Mountain Area

Flat Area

Water Area

Total

USGS DEM 28 29 11 68

ASTER DEM 28 29 11 68

ALOS PRISM DEM 11 8 7 26

FUSED DEM 17 12 10 39

24

Methodology Cont’d.

Objective 3: To verify the result of DEM for several terrain surfaces in term of application suitability.

Comparison

Referenced DEM • ASTER DEM

• ALOS PRISM DEM

• Fused DEM

• Mountain Area

• Flat Area

• Water Area

• Locational Error

• Profile Curvature

• Check Points

Result

25






26

Comparison of the drainage network from

these DEM

27

Drainage networksDrainage networks

(a)

(c)

(b)

(e)

(d) a : 1st Mountain area

b : 2nd Mountain area

d : 1st Flat area

e : 2nd Flat area

c : Water area

28

(a)

(c)

(b)

(e)

(d)

Locational Error

USGS ASTER

ALOS PRISM

mountain Area 1

-6.2

9.0

24.2

39.3

54.5

69.7

84.8

100.0

20 40 60 80 100 125 150 175 200 250 300 350

Epsilon band (m)

% o

f st

ream

lin

e w

ith

in b

uff

er

usgs

aster

fused

alos

ASTER

ALOS PRISM

USGS

Locational Error cont’d

(a)

(c)

(b)

(e)

(d)

Mountain Area 2

0.010.020.030.040.050.060.070.080.090.0

100.0

20 40 60 80 100 125 150 175 200 250 300 350 400 450

Epsilon band (m)

% o

f str

eam

lin

e w

ith

in b

uff

er

usgs

aster

alos

fused

30

(a)

(c)

(b)

(e)

(d)

Locational Error cont’d

Water area

0.0

20.0

40.0

60.0

80.0

100.0

20 40 60 80 100 125 150 175 200 250

Epsilon band (m)

% o

f d

rain

age

net

wo

rk

wit

hin

bu

ffer

Fusion

ASTER

ALOS

USGS

31

Comparison of the terrain relief and Profile Curvature

Terrain relief & Profile Curvature

Min -200

Max 294

Mean -11

SD 72.0

Elevation Profile

0

200

400

600

800

1000

12000

2161

4321

6482

8642

1080

3

1296

4

1512

4

1728

5

1944

5

2160

6

2376

7

2592

7

2808

8

3024

8

3240

9

3457

0

3673

0

3889

1

4105

1

4321

2

4537

3

4753

3

Horizontal Distance (m)

Ele

vati

on

(m

)

ASTER

Reference

Elevation Error Profile

-300

-200

-100

0

100

200

300

400

0

2020

4039

6059

8079

1009

8

1211

8

1413

8

1615

8

1817

7

2019

7

2221

7

2423

6

2625

6

2827

6

3029

5

3231

5

3433

5

3635

4

3837

4

4039

4

4241

3

4443

3

4645

3

horizontal Distance (m)

Ele

vati

on

(m

)

Error

Terrain relief & Profile Curvature Cont’d

Elevation Profile

0200400600800

1000120014001600

0

2560

5120

7679

1023

9

1279

9

1535

8

1791

8

2047

8

2303

8

2559

7

2815

7

3071

7

3327

7

3583

6

3839

6

4095

6

4351

5

4607

5

4863

5

5119

5


Ele

vati

on

(m

)

ASTER

Reference

Elevation Error profile

-300

-200

-100

0

100

200

300

400

500

600

0

2351

4702

7052

9403

1175

4

1410

5

1645

5

1880

6

2115

7

2350

8

2585

9

2820

9

3056

0

3291

1

3526

2

3761

2

3996

3

4231

4

4466

5

4701

5

4936

6

5171

7 horizontal Distance (m)

Err

or

(m)

Error

Min -204

Max 474

Mean 29

SD 98

34

Terrain relief & Profile Curvature Cont’d Profile Elevation

0

200

400

600

800

1000

1200

14000

2440

4880

7320

9759

1219

9

1463

9

1707

9

1951

9

2195

8

2439

8

2683

8

2927

8

3171

8

3415

8

3659

7

3903

7

4147

7

4391

7

4635

7

4879

7

5123

6

5367

6

5611

6


Ele

vatio

n (m

)

Reference

alos prism


-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0

2052

4103

6155

8207

1025

8

1231

0

1436

2

1641

3

1846

5

2051

7

2256

8

2462

0

2667

2

2872

3

3077

5

3282

7

3487

8

3693

0

3898

2

4103

3

4308

5

4513

7

4718

9

4924

0

5129

2

5334

4

5539

5


Ele

vati

on

(m

)

Error

Min -0.68

Max 0.47

Mean -0.01

SD 0.19

35

Terrain relief & Profile Curvature Cont’d

Elevation Profile

0200400600800

1000120014001600

0

1954

3908

5863

7817

9771

1172

5

1368

0

1563

4

1758

8

1954

2

2149

6

2345

1

2540

5

2735

9

2931

3

3126

8

3322

2

3517

6

3713

0

3908

4

4103

9

4299

3

4494

7


Ele

vati

on

(m

)

fusion

reference


-200

-150

-100

-50

0

50

100

150

200

0

1863

3727

5590

7453

9317

1118

0

1304

3

1490

7

1677

0

1863

3

2049

7

2236

0

2422

3

2608

7

2795

0

2981

3

3167

7

3354

0

3540

3

3726

7

3913

0

4099

3

4285

7

4472

0Horizontal Distance (m)

Ele

vati

on

(m

)

error

Min -182

Max 166

Mean 3

SD 34

36



ASTER

Min -53.7

Max 131.2

Mean 17.8

RMSE 52.0

Error Profile at Mountain area

131.2

-53.7

-100.0

-50.0

0.0

50.0

100.0

150.0

15 16 18 19 27 28 29 31 32 33 34 35 41 45 46 47 49 50 51 52 53 55 56 58 59 60 64 69

Points ID

Ele

vati

on

(m

)

ALOS

ASTER

USGS

Fused

USGS

Min -19.8

Max 81.5

Mean 4.8

RMSE 22.2

ALOS

Min -13.0

Max 56.0

Mean 5.4

RMSE 22.6

FUSE

Min -21.0

Max 30.0

Mean 4.0

RMSE 13.2

Comparison of the elevation of the derived DEM with the check points Cont’d

ASTER

Min -59.5

Mean -25.4

Max 29.1

RSME 35.7

Error profile at Flat area

-80.0

-60.0

-40.0

-20.0

0.0

20.0

40.0

60.0

2 6 7 8 9 10 11 12 14 17 21 22 23 24 25 26 36 37 40 42 43 44 61 62 63 64 65 66 67

Points ID

Ele

vati

on

(m

)

ASTER

ALOS

USGS

Fuse

USGS

Min -27.2

Mean -1.4

Max 37.0

RSME 12.8

ALOS

Min -11.0

Mean 5.7

Max 37.1

RSME 17.2

Fuse

Min -47.6

Mean -7.8

Max 37.0

RSME 26.3

39


ASTER

Min -61.5

Mean -11.6

Max 60.3

RSME 35.8

USGS

Min -24.7

Mean -9.4

Max 34.4

RSME 19.2

ALOS

Min -30.0

Mean -1.3

Max 65.0

RSME 31.7

Fuse

Min -44.0

Mean -14.8

Max 19.4

RSME 23.4

Water Area

0.0

200.0

400.0

600.0

800.0

1000.0

1 3 4 5 13 20 30 39 54 68 70

Point ID

Ele

va

tio

n (

m) ASTER

USGS

GCPs

ALOS

FUSED

40

Result

Minimum Maximum RMSE GCP

USGS DEM -27.2 81.5 18.8 68

ASTER DEM -61.5 131.3 43.1 68

ALOS PRISM DEM -30.0 65.0 23.7 26

FUSED DEM -47.0 37.0 21.6 39


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- The quality of ALOS PRISM DEM result is fitted to the referenced DEM.

- The drainage networks of ALOS PRISM are likely fitted to the referenced dataset.

- ALOS PRISM DEM at finer resolution present more detailed features.

- Fused data are more useful for the lack of data and the damaging terrain surface.

Conclusion

Recommendation for Further researches

- Satellite Image should be free cloud for DEM generation

- The quality of DEM result depend on the number of GCPs

- - User must concern the source of data to generate DEM.

- - Apply to use in other area.

THANK YOU VERY MUCHTHANK YOU VERY MUCH

Download - Generation of a Digital Elevation Model using high resolution satellite images By Mr. Yottanut Paluang FoS: RS&GIS

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