8.1 Introduction to Multi-Source Spatial Data
1. Spatial Data
Any data with a locational aspect associated are spatial data. In real life, we often ask the question of where. Where is the bus stop? Where is the post office? To know where is a major part of human life. In our computerized information society, most of the questions of where can be answered in a computer system. However, we are not satisfied with knowing where about something, we may need to know how things at a specific location are related. We want to use what is known to infer those unknown aspects, those unknown locations.
From highly civilized urban areas to areas where human kind is sparsely populated, spatial data play an important role in our modern society. In this chapter, we will focus on our natural environment where different types of natural resources, land covers and uses, and accessibility often concern us. To find out what it is about a particular location, one would read a map. As a surveyor or cartographer, it is our job to make such a map. Traditionally, one has go to the field (a particular place) to measure the location, and record what exists. This is the traditional survey and map approach. A second approach is to use aerial photography and remote sensing techniques, these are the techniques developed since World War I. As the technology advances, we observe a revolutionary leap in instruments and associated data processing techniques. Now satellite based technology is occupying an important position in the geomatics field. We begin with asking the following questions:
What are spatial data?
What are the general approaches to spatial data collection?
What is the current status of spatial data acquisition technology?
What will be achieved in the near future in spatial data acquisition?
Image, is a medium for communication. High Resolution TV is the tool for communication.
Computer provides us the processing power.
Telecommunication is the tool.
Think about FAX machines and modem.