Spatial

Dr Abdullah Hisam Omar

GIS SPATIAL ANALYSIS

ANALISIS LIS

• Analisis Spatial adalah subsistem ketiga didalam LIS/GIS

1) Data Input;

2) Storan Data ;

3) Manipulasi & Analisis Data ;

4) 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).

• 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.

Set Pertanyaan

1) “String” Pertanyaan – seperti nama

• [State_Name] = “Johor”

• [State_Name] = “* J*” * = wild card

• [Owner_Name] = “?mad Bakri”

2) Operator

a) Mathematical Operators

+ Plus A +B

- Minus A-B

* Multiply A*B

/ Divided by A/B

∧∧∧∧Exponentiation A

∧∧∧∧

B

b) "String " operators

+ "kaitan" - - menghubungkan strings dengan penyataan

Penyataan (expression) Hasil (result)

"Ms" + Last_Name Ms. Haliza, Ms.Aliyah, Ms. Janet

"Hello" + "World" Hello World

"4" + "5" 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

B

A A

B

B

Obj A contain Obj B Obj A intersect Obj B Obj A contains entire Obj B

Obj B within Obj A Obj B intersect Obj A Obj B entirely within Obj B

3) Logical Operators

ANDIs “true” if both of its argument (expressions) are true. A record

must satify both of these conditions if it is to be selected

OR

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) Mukim =” skudai” AND Value >=250000

ii) NOT (Mukim = “skudai” AND Value >= 250000)

iii) Mukim = “Skudai” OR “Kulai”

iv) NOT (Mukim = “Skudai”) AND Value >= 250000

4) Boolean Operators

Intersection

A B

A 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 as Schematics:

Mathematician view

Network as Geographic Database:

Geographer view

Network Analysis

NODE x (optional) y (optional)l

1 58 100

2 0 87

3 56 96

Network Data Models and Structures

Table of Nodes

LINK FROM-NODE TO-NODE SHAPE POINT COORDINATES(optional in schematic)

a 2 3

b 1 3

c 4 5

Table of Arc (Links)

NODE VALENCY LIST OF NODES LIST OF LINKS

3 3 1,2,5 –b, –a, d

5 5 3,4,6,10,11 –d, –c, e, f, g

12 4 7,11,13,18 –h, –m, n, s

Node Attribute Table

* Valency = incident links(or node) forming intersections

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 Persembahan 3-D yang sering dilakukan di dalam pakej perisian komersil GIS

o Nilai Z (kebiasaannya ketinggian) direkodkan sebagai attribut bagi setiap titik (x,y)

o Nilai Z boleh digunakan untuk plotan persepktif bagi menjanakan paparan 3 D

o Bukan paparan 3-D yang sebenarnya kerana ketinggian bukan pembolehubah yang bebas ( is

not independent variable )

o Sistem hanya boleh menerima 1 nilai Z diatas permukaan pada sesuatu lokasi/kedudukan

Persembahan 2.5 D

o Satu cara yang menarik untuk memaparkan data topografi dan permukaan yang

bersambungan dari DEM or TIN

o Plotan perspektif dikira dari sebarang titik pandangan

o Lapisan tambahan ditindihkan ( "draped“) keatas permukaan dengan menggunakan warna

ii) 3-D

o menyimpan data di dalam struktur yang merujuk kepada lokasi sebenar ruang 3D (x,y,z)

o Z adalah elemen lokasi bagi sesuatu titik, ianya bukan atribut

o 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

• Definasi: model perwakilan 3 dimensi permukaan rupabumi yang mengandungi koordinat X,Y,Z

yang disimpan dalam bentuk berdigit.

1) Kaedah perolehan Data DEM

i) Kaedah pengukuran dilapangan – tekimetri

ii) Fotogrammetri dan remote sensing - gambar udara dan imej satelit

iii) Ukur GPS

iv) Pendigitan garis kontur – peta topografi

v) Pengimbasan garis kontur – peta topografi

Pemilihan sesuatu kaedah bergantung kepada beberapa faktor;

i) Saiz kawasan

ii) Ketepatan yang diperlukan

iii) Jenis maklumat yang diperlukan

iv) Kos dan masa

Stop pada 12 02 06

Model Ketinggian Berdigit (Digital Elevation Model/DEM)

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) Penjanaan kontur

ii) Penjanaan peta kecerunan

iii) Penjanaan peta aspek – arah permukaaan cerun menghadap ( Utara, selatan, Timur, Barat)

iv) Penjanaan polygon Thiessan

v) Kiraan isipadu/ profil

vi) 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) Harmoni – hubungan antara maklumat peta iaitu bagaimana maklumat peta kelihatan diantara

satu sama lain.

ii) Komposisi- penyusunan maklumat dan keseimbangan struktur

iii) Kejelasan- pengguna mudah untuk mengenalpasti maklumat peta

• Elemen-elemen diatas boleh diwujudkan dengan;

i) Generalisasi – melakukan permudahan pada maklumat

ii) Simbolisasi – keindahan dalam persembahan grafik

iii) Warna – menunjukkan keseimbangan

iv) Tataletak (layout) – komposisi susunan

v) 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"

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

(a) (b)

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)

query for unstable soils

• Stands overlapping with 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 distancefield

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 overlay: Dissolve

• Wizard based

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

• polygon on polygon, line, or point

1

Topological Overlay: Identity

• Xtools based

• Input definition


• Output definition


new theme

both input attribute

data sets

Topological Overlay: Intersect

• only features from overlap area exist in

output

• attributes from both themes exist

• order of input and overlay does not matter



• Wizard based


• new theme is created


• 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


• polygon on polygon only

Topological Overlay: Clip

• “cookie cutter”

• only input theme features and attributes

exist in output



• Wizard based


• Select input & overlay themes


• Specify output theme

Topological Overlay: Erase

• “cookie cutter”

• only input theme features and

attributes exist in output



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:

Spatial

Documents

setiap data nilai

input theme features

spatial analysis

paparan data

analisis data

spatial join

spatial merge

data input