Relationship between remotely sensed data and gis

relationship between remotely sensed data and gis

GIS allows you to link databases and maps to create dynamic displays. Additionally, it provides tools to visualize, query, and overlay those. Entering this box are “flows” of data - both directly relevant and proxy, as well as the three map have enabled a dramatic increase in the performance/cost ratio of computer processors. .. C) For the Integration of Remote Sensing into GIS. The integration of remotely sensed and GIS data* takes four forms: (a) GISs in single-date forest mapping is based on their correlation with forest species or.

Remote sensing technology relies upon technical instruments to collect data over large areas which reduce the manual work that could otherwise have required a lot of people to do. It allows retrieval of data in regions difficult or impossible to access: Remote sensing can allow data to be retrieved in places where humans cannot access such as over volcanic mountains, the ocean depths and several other locations.

It allows collection of more data in a short period of time: Remote sensing technology is used to collect large amounts of data over a large area in a relatively short period of time. The data collected can be used to analyze various aspects of the object or area being analyzed.

Differences between remote sensing and GIS

Mostly use in data collection: Remote sensing technology is mostly used to collect data that can then be analyzed to give information regarding an object or a give phenomenon on the earth surface.

Has a more complex user interface: Remote sensing technology has a more complex user interface than a GIS system because it is mainly used as a data collection tool. It therefore requires more skilled personnel to interpret the interface. It covers a limited study area at a time: Remote sensing technology can be used to collect data over a given area on the earth's surface but the data collected would be limited to the specific area being studied. Remote sensing technology is far less robust than a GIS system because of its limited ability to interpret the data and also more susceptible to damage.

Less ideal for communicating information between departments: Remote sensing technique is not ideal for use as a tool for communicating information between different departments because it is not meant to provide this kind of information. It is a computer system consisting of hardware and software: A GIS system is a computer system that consists of software used to analyze the collected data and hardware that the software would operate in.

It can cope with larger amounts of data: A GIS system is designed to accept and analyze large amounts of data at any given time due to the large capacity of the software and an elaborate personnel system used to analyze the data. It can cover large study areas: A GIS system is designed to cover an elaborate area of study due to its increased capacity to analyze vast and complex information simultaneously. It can cope with unlimited and frequent data edits: Generalization and smoothing, i. These include a variety of functions such as: Zooming or windowing, i.

These are zones at preset distances from any feature, e. Many variations of the data will be retrievable, e.

Geographical information systems and remote sensing in inland fisheries and aquaculture

As well as simple searching and retrieval by theme or area, retrieval using the rules of Boolean Logic is commonly employed. This can be portrayed in the form of Venn diagrams Figure 6. Commands can be input to the GIS such that any combinations of attributes for a theme or an area can be retrieved or any combination of spatial areas.

Complex retrieval commands could involve aerial shapes, lengths of waterway, intensity of current fishing levels, adjacency to urban areas, etc. As well as the previously mentioned zooming and windowing facilities, retrieval functions usually have browse or search facilities. The user will work interactively to perform the analysis. These headings are arbitrary and other classifications could be used, e. Dangermond and Jensen differentiate between polygon-based and grid cell-based analyses noting that, although grid cell analyses are more generalized, they are much more efficient in terms of data storage and in the operation of analytical tasks.

Because there are so many analysis types, we will simply list some of the more common ones. As well as the integration and merging of overlays to produce new mapped surfaces for analysis, other spatial analyses include optimizing route allocations network analysiscalculating intervisibility, slope and aspect, plus digital terrain modelling, location-allocation optimization, trend surface analysis, etc.

For most of these spatial analyses raster-based format is optimal, though rapid advances in software programming is likely to soon mean that data structure differences are irrelevant. These may range from summarizing and describing simple numerical data, e. This includes a number of operations which may be carried out on one or more data layers. Examples include the simple enumerating of features either in total or per polygonmeasuring linear or curvilinear distances between or along objects, calculating areas, perimeters or volumes, calculating angles and recording direction measurements.

From fairly simple measurements rather more sophisticated data can be derived, e. If GIS is thought of as a true processing system then display represents the output from the system. However, unlike most systems where output represents the final processing stage, in GIS output or display can be achieved during any of the functional stages listed in Table 6.

Differences between remote sensing and GIS

This facility is most important since it allows for user control, review, experimentation, etc. Most good GIS software has a range of graphic display features which allows control of label size and fonts, shading ranges, line widths, graphic symbolism, map feature position or composition, etc. This is that which is captured on the visual display unit VDU.

It is the functional user interface in that a visual display is shown of any action that the user takes, and it allows for interactive experimentation or manipulation at no material cost, at great speed and in an almost infinite variety of ways. Before final displays to other output devices, it is important that the prospective output is reviewed and is graphically refined in order to produce meaningful and presentable displays.

This is the output which is printed, via a variety of printers and plotters, onto paper or film. Hard copy displays can be in black and white or multi-coloured. The vast qualitative range achievable is dependent upon either cost factors, associated with achievable graphic quality of the hardware used, or with purpose factors related to the intended use of the output.

The best quality achievable is now superior to that achieved by manual methods - this qualitative ability has been achieved because GIS functioning has been able to combine and absorb skills from the computer graphics and automated cartography fields. These are useful if new data structures resulting from transformation and manipulation processes need to be permanently saved, i. There is a variety of visual formats that the display can take.

Thus graphical displays will consist of an infinite variety of maps or graphs, whilst textual output will include both tables and automatic report writing on data base contents to standard summary sheets. Using varying combinations of alphanumeric characters to produce different shadings, lineprinters were an early output device, though they are still frequently used because they are convenient for researchers or cartographers in giving inexpensive previews before subsequently, using high quality graphic output.

Since lineprinters can only print sequentially, data must be organized by using a suitable software program. The quality of output can be greatly improved by photographic size reduction. Here displays are produced as series of dots, with shading varying with dot density, and lines are represented by strings of dots e. Alphanumeric or special characters can also be printed.

Wide Format and Ink Jet Printers.

relationship between remotely sensed data and gis

These are becoming state-of-the-art for hard-copy printing. Both types allow for printing high quality text and graphics at high speeds, and they are capable of producing hard-copy output in colour.

They are both expensive but require little attention and can be set to run overnight. These consist of a drum which can be rotated in both directions whilst driving a continuous roll of paper.

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A pen on a carriage can move along the drum to plot lines Figure 6. All movement is controlled by the computer. Drum plotters work relatively quickly at typical speeds of 40 cms per second.

relationship between remotely sensed data and gis

They vary in width from 25cms to cms and they can produce multi-colour, high quality output. A drawing pen s can be moved over a flat drawing surface in both x and y directions, or in conjunction to produce curved lines Figure 6. The movements will correspond to grid co-ordinates held in a computer file. Flatbed plotters typically have A3 or A4 plotting areas, facilities for multi-colour plotting and work at speeds of about 25cms per second.

relationship between remotely sensed data and gis

They have a number of advantages over other plotters: Some can be used as digitizers. They can use various forms of writing, scribing or laser implements, on drawing paper, acetate and lithographic film.

They are heavy and stable giving greater precision. A large variety are available, i. A number of colour pens can be fitted which can each be operated by pre-set commands. These operate in a similar way to photocopiers.

relationship between remotely sensed data and gis

An array of nibs electrodes selectively deposit charges on chemically treated paper in the form of an image. Toner is then made to adhere to the charged areas. They produce medium to high quality hard-copy on high quality paper in up to four colour shades. These can deliver monochrome A0 plots at a speed of 20 per hour. They use a paper heating process which affects the chemical properties of the special heat-sensitive paper, causing it to turn black where desired.

The paper is expensive and being light sensitive, it is unsuited to archiving. By film media will be available to give long life impressions. These devices are connected to the port of a graphics workstation and produce hard-copy of the graphic or text image appearing on the monitor. They can produce proofs for editing or final plots for use in documents. There are various different devices working on impact, electrostatic, thermal transfer and ink jet printing technologies.

Trends in these devices include higher resolution, increased use of colour and falling costs. Other output devices include various cameras, optical film writers outputting to colour micro-film and colour slides and light spot projectors. We must start off by defining a data base. This is a large organized collection of data which should be independent of any particular application and therefore usable in any desired way.

It represents the top of a structured hierarchy which consists of fields, records, files and data bases. To exemplify this - if a data base were to be established on river water quality within a country or region, it would be necessary to take a sequence of steps: At each river sampling point measurements of different water quality parameters would be made.

Each water qualitative parameter measured observed would constitute a field. A collection of all the qualitative measurements fields taken at one location would be a record. A collection of all records made along one river, or stretch, would make up a file.

A collection of all files for the country or region would make up a data base.

Applications of Remote Sensing and GIS in Mineral Resources

Individual files within the data base may be organized in various ways, and the whole data base can be structured in several ways, e. A DBMS is a computer programme for creating, maintaining and accessing a data base.

They can mostly handle numeric and alphanumeric data and they can provide the essential linkage between the user, graphic and other data, plus a range of external computer packages for mapping and statistical analyses. The reasons for having a DBMS are that all large collections of data, which are available to more than one user, require rules to maintain and manage them so that they remain usable. Since the volume of data is increasing exponentially, the importance of management is being increasingly magnified.

It is also most important that large data bases have efficient storage structures, both to minimize storage space and so that they can be efficiently searched or analyzed, and users need to give careful consideration to the exact requirements of the data structure and contents before establishing files or data bases.