DATA SPASIAL

CHAPTER 2

SPATIAL DATA

Typical GIS questions answered by maps such as those

used to identify, to locate, or to find geospatial patterns

Contoh Aplikasi SIG

Searching for sites : lokasi

pembuangan limbah

radioaktif

Evaluating land use planning

Finding a new home

Learning outcomes

Explain the difference between data and information

Describe the main characteristics of spatial data

Give examples of map projections and explain why they are important

Provide details of different methods of spatial referencing

Define topology

Explain the thematic characteristics of spatial data

List the main sources of spatial data

Explain why data standards are an important issue in GIS

Introduction

All Geographical Information Systems are computer representations of some aspect of the real world. It would be impossible to represent all the features in which you are interested in a computer, so GIS present a simplified view of the world

Being able to develop and understand a simplified view of the world is an important first step for your own GIS projects.

The simplified view of the real world adopted by GIS is often termed a model. A model is „a synthesis of data‟ (Haggett and Chorley, 1967) which is used as a „means of “getting to grips” with systems whose spatial scale or complexity might otherwise put them beyond our mental grasp‟ (Hardisty et al., 1993).

Haggett and Chorley (1967) point out that a spatial model places emphasis on reasoning about the real world by means of translation in space. This is exactly the reason why GIS is used to solve geo-graphical problems

The difference between data and information

Before looking at how spatial models are constructed using a GIS it is necessary to consider the character of the spatial data they use as their raw material.

Data are observations we make from monitoring the real world. Data are collected as facts or evidence that may be processed to give them meaning and turn them into information

Information is data with meaning and context added (Hanold, 1972)

The character of Spatial Data

The traditional method for storing, analyzing and presenting spatial data is the map. The map is of fundamental importance in GIS as a source of data, a structure for storing data and a device for analysis and display.

Perhaps more importantly, maps have shaped the way most of us think about space in two dimensions. Therefore, understanding maps and how they are produced is an essential starting point for exploring the characteristics of spatial data.

Maps take many different forms and come at a range of different scales

Eventhough there are many different types of maps

the mapping process is of a general nature. During this

process the cartographer must (after Robinson et al, 1995):

establish the purpose the map is to serve;

define the scale at which the map is to be produced;

select the features (spatial entities) from the real world which must be portrayed on the map;

choose a method for the representation of these features (points, lines and areas);

generalize these features for representation in two dimensions;

adopt a map projection for placing these features onto a flat piece of paper;

apply a spatial referencing system to locate these features relative to each other; and

annotate the map with keys, legends and text to facilitate use of the map.

DATA

SPASIAL

DATA SPASIAL BERDASAR DIMENSI

- Positional Data : data nol dimensi - Linear Data : data berdimensi satu - Areal Data : data berdimensi dua - Volumetric Data : data berdimensi tiga

INFORMASI GEOSPASIAL

Spasial adalah aspek keruangan suatu objek atau kejadian yang mencakup lokasi, letak, dan posisinya.

Geospasial atau ruang kebumian adalah aspek keruangan yang menunjukkan lokasi, letak, dan posisi suatu objek atau kejadian yang berada di bawah, pada, atau di atas permukaan bumi yang dinyatakan dalam sistem koordinat tertentu.

Data Geospasial adalah data tentang lokasi geografis, dimensi atau ukuran, dan/atau karakteristik objek alam dan/atau buatan manusia yang berada di bawah, pada, atau di atas permukaan bumi.

Informasi Geospasial adalah data geospasial yang sudah diolah sehingga dapat digunakan sebagai alat bantu dalam perumusan kebijakan, pengambilan keputusan dan/atau pelaksanaan kegiatan yang berhubungan dengan keruangan.

Sumber: Pasal 1 Ketentuan Umum UU Informasi Geospasial

HAL YANG PERLU DIPERHATIKAN TERKAIT

PENYAJIAN DATA SPASIAL

Skala

Entitas Spasial

Generalisasi

Proyeksi

Sistem Koordinat (referensi spasial)

Topologi

Sumber data Spasial

Topologi