GIS Analysis Functions

Transkripsi

1 FUNGSI ANALISIS GIS

2 GIS Analysis Functions 4 Katagori Umum Retrieval/Klasifikasi/Pengukuran Overlay (tumpang susun) Neighborhood (Kedekatan) Connectivity (Konektivitas)

3 RETRIEVAL /KLASIFIKASI /PENGUKURAN

4 Retrieval, Klasifikasi, & Fungsi Pengukuran Retrieval Pencarian selektif (Selective Search) Klasifikasi/Classification (Overlays, combine) Mengidentifikasi satu set obyek yang merupakan bagian dari grup obyek yang sama Mendefinisikan sebuah pola Pengukuran/Measurement Jarak, panjang, luasan/area, dsb

5 Retrieval: Pencarian selektif (Selective Search) Sebuah alamat terpilih karena berada dalam lingkaran

6 Reklasifikasi (Vector) Dissolving untuk agregasi polygons

7 Reklasifikasi berdasarkan Luasan Bekerja dengan luas > 80 ha

8 Reklasifikasi berdasarkan hubugan (Contiguity) Bekerja dengan obyek individu, bukan dengan klas obyek secara keseluruhan

9 Reklasifikasi Nilai Bekerja dengan elevasi antara 20 and 40 m Ubah feet ke meters

10 Operasi Jarak Vektor: Buffers & Setbacks Gambar sederhana dari operasi buffers dan setback. NOTE: buffers go outward from lines or areas; setbacks run inside of areas (not lines). Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 154. fig. 6-1.

11 Buffer: Illustrasi Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 60. fig. 6-3.

12 OVERLAY (TUMPANG SUSUN)

13 2. Fungsi Overlay (Tumpang Susun) Aritmatika penambahan, pengurangan, pembagian, perkalian Logika menemukan di mana kondisi tertentu terjadi (and, or, >, <, etc.) Perbedaan metode Raster & Vector Vektor baik untuk data yang tidak terlalu komplek/jarang Raste mudah dalam kalkulasinya Overlay (demo addition)

14 Overlay untuk Vector 3 tipe utama vector overlay point-in-polygon line-in-polygon polygon-on-polygon

15 Vector based overlay Contoh point-on-polygon

16 Vector based overlay Contoh line-on-polygon

17 Vector based overlay Contoh polygon-in-polygon

18 Overlay Dasar Raster: Penjumlahan sederhana (Simple Addition) Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 144. fig

19 Raster Overlay: Kombinasi Boolean Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 125. fig. 5-3.

20 Fungsi Neighborhood membentuk keluaran nilai dari setiap sel lokasi sesuai dengan kedekatan dengan yang lainnya. NEIGHBORHOOD (LINGK-SEKITAR)

21 3. Fungsi Neighborhood Fungsi Dasar Rata-rata, perbedaan, mayoritas, minimum/maksimum, dan total Parameter yang dicari: Lokasi Target Spesifikasi dari lingkungan sekitar Fungsi untuk melaksanakan dalm neighborhood element

22 3. Neighborhood Function (cont) Operasi pencarian most common neighborhood operation Contoh Menghitung jumlah dari pelanggan yang berjarak 2 km dari sebuah toko.

23 3. Neighborhood Functions (cont) Point atau Line dalam Operasi Poligon Fungsi pencarian spesifik Buffers (demo - point, line, polygon) Thiessen Polygons Operation defines the individual area of influence around a point used to predict values at surrounding points from a single point observation

24 Example: Neighborhood Function Thiessen Polygons

25 Fungsi Neighborhood: Contoh Tema Zona: Watersheds (DAS) Nilai tema: Elevasi Statistic type: Mean Output: Rata-rata elevasi dari tiap watershed

26 Fungsi Neighborhood: 10x10 filter rata-rata dalam DEM

27 CONNECTIVITY

28 4. Fungsi Connectivity Digunakan untuk akumulasi nilai di atas sebuah area yang di analisis Parameter yang dicari: Spesifikasi bagaimana cara element2 spasial terkoneksi Aturan yang secara spesifik membolehkan pergerakan antar koneksi Unit ukuran

29 4. Fungsi Connectivity (cont). Operasi Proximity Pengukuran jarak antara dua obyek Tidak terbatas pada jarak saja; bisa noise, time, pollution, etc. Parameter yang dicari: Lokasi target Unit dari pengukuran Fungsi untuk menghitung proximity (distance/time/noise) Area yang akan di analisis

30 Example: Connectivity (Vector) Proximity Operation: Road Buffer

31 Example: Connectivity (Vector) Proximity Operation: Buffer Generation

32 Example: Connectivity (Vector) Points Lines Polygons Proximity Operation: Buffer Types

33 Example: Connectivity (Vector) Proximity Operation - Buffers & Setbacks Diagram of simple buffers and a setback. NOTE: buffers go outward from lines or areas; setbacks run inside of areas (not lines). Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 154. fig. 6-1.

34 4. Fungsi Connectivity (cont). Operasi Contiguity spatial units are connected - defines unbroken area Contiguity measures: size of neighboring area(s) shortest/longest straight line distance across adjacent area(s) specific shape of neighboring area(s)

35 Contiguity Functions Combines adjacent units together when they share a common attribute

36 4. Fungsi Connectivity (cont). Operasi Jaringan (Network Operations) set of interconnected lines that represent a set of features through which resources flow Fungsi jaringan umum (Common network functions) Permasalahan shortest path location-allocation modeling (resource allocation) traveling salesperson problem (route optimization) route tracing (prediction of network loading)

37 4. Connectivity Functions (cont). Operasi Analisis Visibiliti identification of areas of terrain that can be seen from a particular point on the surface Viewshed Operation uses digital elevation model data (DEMs) or... digital terrain model data (DTMs) or... triangulated irregular network data (TINs)?

38 Connectivity Function Example: Viewshed Analysis Image Source: Chrisman, Nicholas.(2002). 2 nd Ed. Exploring Geographic Information Systems. p 198. fig

39 Viewshed aka Intervisibility

40 Environmental Impact Analysis 3D landscape model impact on natural beauty

41 Another term: Surface Analysis Surface functions density, contour, interpolation functions aspect, slope, hillshade, etc. watershed analysis and modeling (flow direction, flow accumulation, flow length, watershed delineation, stream ordering) visibility modeling/mapping determine the area that can be "seen" from the target location

42 The 3 rd Dimension: Height Analysis Contours Hill shading Spot height symbols Cliff & slope symbols Viewpoint symbols

43 Analysis: Summation GIS does not always provide exact answers to problems, but by identifying trends based on geography, GIS can reveal patterns that can help us make informed decisions. A GIS can improve decision-making; it cannot make decisions for us.

44 Flood Risk 3D height data changing water levels-danger areas

45 Derived Mapping: Data from images Numerical Values Color Representation

46 Derived Mapping: Data from images Aerial Imagery Digitized Buildings

47 Derived Mapping: Data from images Satellite Imagery Derived Area Map This is a goal: Not there yet!

48 Retail: Site Selection Existing stores, 15 min. drive time, demograhics

49 Airport Noise Pollution noise complaints mapped by address location