Spatial

GIS SPATIAL ANALYSIS

Dr Abdullah Hisam Omar

ANALISIS LIS •

Analisis Spatial adalah subsistem ketiga didalam LIS/GIS 1) 2) 3) 4)

Data Input; Storan Data ; Manipulasi & Analisis Data ; Paparan Data.

Data Input

Storan Data

Analisis Data

Paparan Data

LIS/GIS

• Fungsi analisis spatial menjawab persoalan spatial seperti: • • • •

Dimana (Where) – letaknya FKSG di dalam kampus UTM Berapa(What) – jumlah keluasan kawasan pertanian tersebut Mengapa (Why) – lot A lebih sesuai didirikan bangunan berbanding lot B Manakah (Where) – laluan terbaik paip air dari Skudai – Kota Tinggi. SGU3633

What is spatial analysis? • Methods for working with spatial data – to detect patterns, anomalies – to find answers to questions – to test or confirm theories • deductive reasoning

– to generate new theories and generalizations • inductive reasoning

• "a set of methods whose results change when the locations of the objects being analyzed change"

What is Spatial Analysis (cont.) • Methods for adding value to data – in doing scientific research – in trying to convince others

• Turning raw data into useful information • A collaboration between human and machine – Human directs, makes interpretations and inferences – Machine does tedious, complex stuff

•

Terdapat kesilapan menggunakan analisis spatial seperti : Ο Melakukan analisis spatial menggunakan kombinasi data dari skala kecil dan besar , serta mengganggap hasilnya adalah setepat data skala besar. Ο Menjalankan perbandingan skala pengukuran spatial diantara data jenis nominal (jenis tanaman, pokok dll) dengan data nisbah (harga tanah, jumlah pendapatan dll).

Set Pertanyaan •

Suatu definasi yang jitu iaitu merujuk kepada pemilihan yang dikehendaki.

•

Pembentukan set pertanyaan melibatkan atribut,operator dan pengiraan.

•

Kebiasaannya, set pertanyaan akan menggunakan kolum (field name) dan konstan(nilai tertentu) o POP_1990 > 17000 o MUKIM <> “ Skudai” o POP_1990> POP_1980 *1.2 o ([AREA] >= 100) and ([AREA] <= 200) ---- POP_1990, MUKIM, AREA adalah nama kolum ----- 17000,Skudai,100 & 200 adalah konstan.

1) “String” Pertanyaan – seperti nama • • •

[State_Name] = “Johor” [State_Name] = “* J*” * = wild card [Owner_Name] = “?mad Bakri”

2) Operator a)

Mathematical Operators

+ * / ∧ b)

Plus

A +B

Minus

A-B

Multiply

A*B

Divided by

A/B

Exponentiation

A B

∧

"String " operators +

"kaitan" - - menghubungkan strings dengan penyataan

Penyataan (expression) "Ms" + Last_Name "Hello" + "World" "4" + "5"

Hasil (result) Ms. Haliza, Ms.Aliyah, Ms. Janet Hello World 45

c)

Comparison Operators = <> > < >= <=

Equal Not equal Greater than Less than Greater than or equal to Less than or equal to

1)

Numerical comparisons = based on numerical values & constants i) Med_Age =42 ii) Amount <>2300

2)

String comparisons = based on character contents of the string i) Vendor = "Esri" ii) Vendor <> "Esri"

3)

Date Comparisons Format English = October 9,1991 ( month,day,year) i) Received = "10-9-91" ii) Recived > "10-9-91

4)

Logical Comparisons "T" = True , or "F"= False cth ; dari kolum Deliver = "T" Deliver = "F"

5)

Geographic Operators -Memilih objek berasaskan hubungan spatial kepada objek yang lain. A

A

A B B

B

Obj A contain Obj B Obj B within Obj A

3)

Obj A intersect Obj B Obj B intersect Obj A

Obj A contains entire Obj B Obj B entirely within Obj B

Logical Operators AND

OR

Is “true” if both of its argument (expressions) are true. A record must satify both of these conditions if it is to be selected Is “true” if either one or both of its argument are true. A record need satisfy only one of these conditions if it is to be selected. It is also selected if both of its conditions are satisfied.

NOT

Is “true” if its argument is false. A record is selected if it does not meet the stated condition.

Example; i) ii) iii) iv)

Mukim =” skudai” AND Value >=250000 NOT (Mukim = “skudai” AND Value >= 250000) Mukim = “Skudai” OR “Kulai” NOT (Mukim = “Skudai”) AND Value >= 250000

4)

Boolean Operators

A

B

A

Intersection

B

Union

Contoh pertanyaan; spatial, atribut dan set pertanyaan

SQL in Data Analysis • structured or standard query language • SELECT FROM counties WHERE median value > 100,000

Zon Penimbal (Buffer) •

Satu jenis analisis kehampiran

•

Kawasan/zon yang dijanakan dari jarak sesuatu objek peta yang diberi.

•

Boleh dijanakan untuk sesuatu objek berdasarkan nilai attribut objek-objek tersebut.

•

Dua kaedah buffering:

•

1 buffer untuk kesemua objek

•

1 buffer untuk setiap objek

•

Buffer menjurus kepada analisis spatial atau menentukan kawasan kritikal bagi sesuatu analisis.

GIS ANALYSIS

Buffering • Buffer – The creation of a zone of interest around a geographic entity – Can be a zone of exclusion or inclusion.

• Most commonly the buffer is created by defining a radius around all features of interest. • A circle around points, an area around lines or polygons.

Point Buffers • Distance from Station in meters

Line Buffering • Buffers at 100 m intervals to 500 m from Bank Street

Buffering • distance or proximity analysis • constant or variable width from input features

Buffering • Wizard-based

Buffering • Can create a new shapefile

Buffering • Can create a simple graphical primitives • Buffer inside, outside or both

Buffer untuk setiap objek

Buffer untuk kesemua objek

Buffer keatas garisan

Network Analysis

Network as Schematics: Mathematician view

Network as Geographic Database: Geographer view

Network Data Models and Structures NODE

x (optional)

y (optional)l

1

58

100

NODE

VALENCY

LIST OF NODES

LIST OF LINKS

3

3

1,2,5

–b, –a, d

Node Attribute Table 2

0

87

3

56

96

5

5

3,4,6,10,11

–d, –c, e, f, g

12

4

7,11,13,18

–h, –m, n, s

Table of Nodes

* Valency = incident links(or node) forming intersections

LINK

FROM-NODE

TO-NODE

a

2

3

SHAPE POINT COORDINATES (optional in schematic)

Table of Arc (Links) b

1

3

c

4

5

LINK

STREET NAME

ADDRESSES (L)

ADDRESSES (R)

CLASS

LENGTH (km)

LANES

SPEED LIMIT (km/h)

c

El Camino Real=Hwy101

—

—

Freeway

1.42

3

100

–c

El Camino Real=Hwy101

—

—

Freeway

1.44

3

100

m

Hollister Ave

1201-1299

1200-1298

Arterial

0.23

2

80

t

Walnut Lane

598-200

599-201

Residential

0.68

1

45

Arc (Link) Attribute Table (record key is Link ID or pair of nodes)

Network Analysis Application

Analisis Permukaan •

Analisis permukaan si ketiga bagi melibatkan proses menganalisis taburan pembolehubah (variables) yang dapat dipersembahkan sebagai dimensi ketiga data spatial.

•

Ketinggian adalah contoh semulajadi pembolehubah dimensi ketiga kerana perubahan didalam ketinggian menghasilkan permukaan muka bumi.

•

Pemprosesan asas maklumat permukkan adalah interpolasi spatial.

•

Interpolasi spatial membolehkan permukaan yang bersambungan dijanakan dari set titik-titik.

•

Terdapat dua cara berbeza untuk mempersembahkan dimensi vertikal ( dimensi ketiga) di dalam GIS : 2.5-D dan 3-D

i) 2.5 D o o o o o

Persembahan 3-D yang sering dilakukan di dalam pakej perisian komersil GIS Nilai Z (kebiasaannya ketinggian) direkodkan sebagai attribut bagi setiap titik (x,y) Nilai Z boleh digunakan untuk plotan persepktif bagi menjanakan paparan 3 D Bukan paparan 3-D yang sebenarnya kerana ketinggian bukan pembolehubah yang bebas ( is not independent variable ) Sistem hanya boleh menerima 1 nilai Z diatas permukaan pada sesuatu lokasi/kedudukan

Persembahan 2.5 D o o o

Satu cara yang menarik untuk memaparkan data topografi dan permukaan yang bersambungan dari DEM or TIN Plotan perspektif dikira dari sebarang titik pandangan Lapisan tambahan ditindihkan ( "draped“) keatas permukaan dengan menggunakan warna

ii) 3-D o o o

menyimpan data di dalam struktur yang merujuk kepada lokasi sebenar ruang 3D (x,y,z) Z adalah elemen lokasi bagi sesuatu titik, ianya bukan atribut Data sesuatu titik boleh direkodkan dengan koordinat (x,y) yang sama dan berlainan nilai Z cth., pelan srata,kedalaman/ketinggian di laut atau atmosfera, lapisan geologikal telaga

Model Ketinggian Berdigit (Digital Elevation Model/DEM) •

Definasi: model perwakilan 3 dimensi permukaan rupabumi yang mengandungi koordinat X,Y,Z yang disimpan dalam bentuk berdigit.

1) Kaedah perolehan Data DEM i) ii) iii) iv) v)

Kaedah pengukuran dilapangan – tekimetri Fotogrammetri dan remote sensing - gambar udara dan imej satelit Ukur GPS Pendigitan garis kontur – peta topografi Pengimbasan garis kontur – peta topografi

Pemilihan sesuatu kaedah bergantung kepada beberapa faktor; i) ii) iii) iv)

Saiz kawasan Ketepatan yang diperlukan Jenis maklumat yang diperlukan Kos dan masa

Stop pada 12 02 06

2)

Interpolasi DEM • Interpolasi diperlukan apabila wujud: o Penukaran struktur data rawak ke grid o Penukaran struktur kontur ke grid o Penjanaan garis kontur yang baru • Interpolasi dilaksanakan dengan anggapan: o Setiap data nilai Z adalah bersifat bersambungan o Setiap data nilai Z bergantung kepada nilai ketinggian jirannya.

3)

Penggunaan Data DEM Didalam Analisis Permukaan i) ii) iii) iv) v) vi)

Penjanaan kontur Penjanaan peta kecerunan Penjanaan peta aspek – arah permukaaan cerun menghadap ( Utara, selatan, Timur, Barat) Penjanaan polygon Thiessan Kiraan isipadu/ profil Kajian kesalingnampakan – berguna dalam aplikasi telekomunikasi & ketenteraan. Tujuannya ialah untuk mencari tempat yang boleh kelihatan dari satu titik cerapan. vii) Pembentukkan Model 3D (pandangan perspektif, bird view) & simulasi ( flying through)

Peta Kecerunan (Slope)

Peta Aspek (Aspect)

Kajian Kesalingnampakan

Permukaan Grid

DEM

Pandangan Persepktif 3D

Analisis Paparan • • • •

Lokasi, teks dan simbol digunakan untuk membentuk pandangan “real world” (geografi) di dalam minda pengguna. Keberkesanan translasi ini adalah hasil ketepatan peta, teks yang mudah dibaca, kejelasan simbol dan dan kesesuain pemilihan teknik pemetaan Analisis paparan juga melibatkan pengukuran lokasi, kawasan, jarak dan ketinggian. Analisi paparan perlu menitikberatkan 3 elemen keindahan peta seperti berikut; i) ii) iii)

•

Harmoni – hubungan antara maklumat peta iaitu bagaimana maklumat peta kelihatan diantara satu sama lain. Komposisi- penyusunan maklumat dan keseimbangan struktur Kejelasan- pengguna mudah untuk mengenalpasti maklumat peta

Elemen-elemen diatas boleh diwujudkan dengan; i) ii) iii) iv) v)

Generalisasi – melakukan permudahan pada maklumat Simbolisasi – keindahan dalam persembahan grafik Warna – menunjukkan keseimbangan Tataletak (layout) – komposisi susunan Penghurufan – kenampakan teks

Elemen-elemen Keindahan Peta

Contoh: Analisis Visualisasi (3D)

Analisis Tindihan (Overlay) •

Analisis tindihan adalah analisis yang melibatkan multi-lapisan atau multi objek. Operasi analisis dilakukan ke atas multi-lapisan secara serentak.Ia berdasarkan kepada hubungan logikal diantara lapisan/objek data.

•

Operasi tindihan: o data vektor - sangat komplek dan memakan masa o data raster - mudah dan cepat

•

Jenis operasi tindihan: o tindihan CAD - paparan sahaja o tindihan aritmatik - dalam data raster o tindihan topologikal - menjana poligon, topologi dan atribut baru

Proses tindihan secara manual

Tindihan raster

Tindihan Topologi

Proses Tindihan: Menghasilkan "Real World"

(a)

(b)

Hasil Tindihan: (a) Lapisan-lapisan objek; (b) Hasil tindihan

Analyzing spatial relationships • Relationships between features – Proximity – Containment – Overlap

• All based on feature geometry_

Selecting points near a line (proximity) • Find gates near streams

Selecting adjacent features (proximity of 0) • Stands adjacent to other stands

Line-on-polygon selection (intersection, proximity of 0, overlap) • Roads and streams within stands

Polygon-on-line selection (intersection, proximity of 0, overlap) • Stands traversed by streams

Point-in-polygon selection (containment) • CFI plots within 30-40 years old stands

Point-in-polygon selection • Spatial selections can be used to examine attribute data

30-40 year old stands are underrepresented in inventory

Polygon-on-point selection • Where are all stands with unsampled plots? query for “no sample”

Polygon-on-polygon selection (containment, overlap) • Stands overlapping with unstable soils query for unstable soils

Spatial join • Theme attribute tables are joined on the shape field • Features are related and compared for distance and containment • Based on feature geometry

Spatial join: containment • Records are joined for features within other features polygon attributes are attached to points

related fields can be used for display

Spatial join: proximity • Appends tables and automatically adds distance field distance from plot centers to roads

distance used as display field

Spatial merge

• A special case of the tabular summary • Features with identical attribute values are merged together • Table records are joined • A new theme is created_

Spatial merge • Uses the Merge_Shape summary statistic summarize the Age_Class_1999 field

creates a new theme a single feature for each unique age class

Spatial merge • Merges features as well as records

multiple objects, one record

Topological Overlay: Overview • Uses arc-node topology data model for theme-to-theme relationships • Relationships of containment • Various analytical functions • Quantify length/area of overlap • All functions are accessed with GUI/wizards

Topological Overlay: Arc/node topology data model

Topological Overlay: Overview • Always uses polygon as the overlay theme • Output is the same as the input

Topological Overlay: How it works • polygons are from separate themes • no explicit spatial relationship between Streams & Stands

• new nodes are created • topology is rebuilt • spatial relationship is made explicit

Topological Overlay: How it works • lines are split at polygon boundaries • lines take on attributes of overlapping polygons

Topological overlay: Dissolve • removes boundaries between polygons or nodes between arcs • features with same attributes are dissolved • identical to spatial merge

Topological • Wizard based

overlay: Dissolve

Topological overlay: Union • all input features from both themes remain • attribute values are assigned by containment • polygon & polygon only

Topological overlay: Union • Wizard based

Topological overlay: Identity • all features from input theme persist • attributes from both themes exist where there is overlap • order of input and overlay matters

1

• polygon on polygon, line, or point

Topological Overlay: Identity • Xtools based • Input definition

Topological Overlay: Identity • Output definition

Topological Overlay: Identity both input attribute data sets

new theme

Topological Overlay: Intersect • only features from overlap area exist in output • attributes from both themes exist • order of input and overlay does not matter • polygon on polygon, line, or point

Topological Overlay: Intersect • Wizard based

Topological Overlay: Intersect • new theme is created

Topological Overlay: Intersect • Because geometry fields are not automatically updated, must use other methods of calculating geometry values • Sample script(s), Xtools

Topological Overlay: Update • • • • •

all features exist in output “underlapping” features from input are erased attributes only from input theme exist in output order of input and overlay matters polygon on polygon only

Topological Overlay: Clip • “cookie cutter” • only input theme features and attributes exist in output • polygon on polygon, line, or point

Topological Overlay: Clip • Wizard based

Topological Overlay: Clip • Select input & overlay themes

Topological Overlay: Clip • Specify output theme

Topological

Overlay: Erase

• “cookie cutter” • only input theme features and attributes exist in output • order of input and overlay matters • polygon on polygon, line, or point

Topological Overlay: Erase • XTools based

Topological Overlay: Erase

Spatial Relations in ArcView •

• • •

•

•

Are Completely Within - selects features in the target themes that are completely within one or more of selected features of the active theme. Completely Contain - selects features in the target themes that completely contain one or more of the active theme. Have their Center In - selects features in the target themes if their center falls inside the features of the active theme. Contain the Center Of - selects features in the target themes that contain the center of one or more of the active theme features Intersect - selects features in the target themes that intersect the features in the target. At least one common point. If the active and target are the same, Intersect will select adjacent features. Are Within Distance Of - selects features in the target themes that are within a specified distance of the active theme features. You can specify the type of distance units in the View Properties dialog box.

SOME EXAMPLES AND APPLICATIONS

SATELLITE IMAGES: K.SELANGOR

Facilities Management

Crop Management

Crime Analysis

Road Management

Military Application: