Bahan Ajar Al Jabar Citra.pdf

Aljabar Citra (Algebra)

Dedy Fitriawan [email protected] +62813 74 678080

Pengolahan Citra Digital

Raster Calculation: Map Algebra

Map Algebra supports three types of expressions: •Arithmetic operators (+, -) •Boolean operators (AND, OR) •Relational operators (>, <)

Map Algebra • Sebuah pertanyaan; “bagaimana cara mengidentifikasi suatu area tanpa vegetasi dengan lereng lebih besar dari 15%, area tersebut diidentifikasi sebagai area risiko tinggi”

slope

U vegetation • Perlu kerangka aljabar untuk mengoperasikan • Data eksisting bisa di cuplik berdasarkan karakteristik DN

Raster Analysis • Raster math • Statistics: min, max, mean, std. dev. • Local, Neighborhood, Zonal • Distance (cost) • Topography: Slope, aspect, contours • Reclassify • Raster / Vector Conversions

2*Layer A

LayerA + LayerB

Arithmetic Operators (+, -, *, /) Mathematical Functions (Sqr, exp, int, etc.) Comparison Operators (>, >=, =, <>, <, <=) Boolean Operators (AND, OR, NOT, XOR)

• Toolbox → Spatial Analysis Tools → Map Algebra → Raster Calculator

3

4

2

3

-

0

1

2

3

=

• Contoh Sederhana 4

1 5 2

4

6

6 2

10 5

8 5

+

4 6 13

7

Input 1

Input 2

3

2 7

7

2

4

7

4

6

3

2

3

1

1

6

3 3

2

3

4

2 6

2

7

6

4

1

3

6 5 5

10

= Output

5

7 4

input

49

25 16

output = sqr(input)

input

output = tan(input)

output = reclass(input)

output = log2(input)

Supervised classification

1 3 4 2 4 5 1 2 4

1

4

2

3

5

Old class

1 2 New class

1 1 2 1 2 2 1 1 2

Unsupervised classification 5 diversity 1 3 4 2 4 5 1 2 4

4 modal

5 3 mean

maximum

1 minimum

Zonal functions 5

7 4

input

Zone 2 zone Zone 1 9

7

9

7

9 9

7

9 9

9 9

7

7

7 7

7

output = zonalsum(zone, input)

input

535.54

766.62 output = output = zonalthickness(input_zone)

Input_zone

127

6280

160

10800

zonalmax(input_zone, output = input) zonalperimeter(input_zone)

Raster Analysis: reclass

Identifying suitable habitat Slope < 20 degrees

Green = suitable slope (cell value = 1) Red = unsuitable slope (cell value = 0)

South facing slopes aspect between 150 and 200 degrees.

Green = suitable aspect (cell value = 1) Red = unsuitable aspect (cell value = 0)

Identify Slope < 20 degrees (Alternative method)

“Slope” < 20

“suitable aspect” * “suitable slope”

suitable_habitat

Cell value = 1… Suitable slope & Suitable aspect 1

0

0

1

1

1

0

0

0

0

0

1

0

1

0

1

*

0

0

0

0

0

1

1

0

1

1

0

1

1

1

0

1

=

0

0

0

0

0

1

0

0

0

0

0

1

0

1

0

1

Conditional Operator • Con(,<true>,) • Given a raster “condition”:

• Puts the true value where true and false value where false

Con!

Elevations over 3000 meters • Con("W100N40.DEM“>3000,0,1)

Elevations over 3000 meters

Input Raster Output Extent Output Cell Size Mask

Output raster

Format Laporan (Senin 15.00 WIB by e-Learning) Cover Pengantar

Teori Metode

Hasil • • • Kesimpulan Lampiran

Landsat 8 (Band Multispectral saja), Panchromatic, Cirrus, Thermal dan `Quality hitung masing-masing band dengan metode dibawah (4 point) Ceritakan Kegunaan Tugas ini, hubungkan dengan fungsi statistic dalam citra, DEM, Citra dan sampaikan pembagian path/row landsat individu Cari dari buku sumber maupun internet, apa itu landsat dan DEM Serta aljabar citra a. sampaikan metode aljabar citra (aritmatika, Fungsi Statistik, Comparison/reclass, Conditional) b. uraikan identitas citra yang di gunakan berbentuk table No. / Generasi Landsat / ID landsat / Tanggal c. Uraikan rumus dan cara menggunakannya di software (software bebas) bikin ulasan dan rincian citra landsat 8 uraikan: Aritmatika (kabataku) Statistik (mean, std, max, min, modus) Reclass conditional (>, >=, =, <>, <, <=)

Tidak, Aljabar