What do geographers use remote sensing for

The data can then be presented in layered visualizations using digital geographic maps. The advantages of remote sensing include the ability to collect information over large spatial areas; to characterize natural features or physical objects on the ground; to observe surface areas and objects on a systematic basis and monitor their changes over time; and the ability to integrate this data with other ….

GPS also advances scientific aims such as weather forecasting, earthquake monitoring, and environmental protection. The American taxpayer pays for the GPS service enjoyed throughout the world. All GPS program funding comes from general U. The bulk of the program is budgeted through the Department of Defense, which has primary responsibility for developing, acquiring, operating, sustaining, and modernizing GPS. At present, there are total 27 satellites in orbit and all are operational.

You need four satellites because each data from one satellite put you in a sphere around the satellite. By computing the intersections you can narrow the possibilities to a single point. Three satellites intersection places you on two possible points. They commonly use maps, globes, atlases, aerial photographs, satellite photographs, information graphics, and a computer program called GIS.

Read below to learn about different tools. A map is a flat representation of a part of Earth. Geographers use many different types of maps. There are two types of remote sensing technology, active and passive remote sensing. Active sensors emit energy in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target.

Remote sensing data provides essential information that helps in monitoring various applications such as image fusion, change detection and land cover classification. Remote sensing is the science of obtaining information about objects or areas from a distance, typically from aircraft or satellites.

For example, a laser-beam remote sensing system projects a laser onto the surface of Earth and measures the time that it takes for the laser to reflect back to its sensor.

Remote sensing technology is used in a wide variety of disciplines in thousands of different use cases, including most earth sciences, such as meteorology, geology, hydrology, ecology, oceanography, glaciology, geography, and in land surveying, as well as applications in military, intelligence, commercial, economic.

An advantage of airborne remote sensing, compared to satellite remote sensing, is the capability of offering very high spatial resolution images 20 cm or less. The disadvantages are low coverage area and high cost per unit area of ground coverage. Which of the following is not a principle of remote sensing? Explanation: Remote sensing involves certain principles which are applied for having a good result of the desired output.

The principles are electromagnetic energy, electro-magnetic spectrum, interaction of energy with atmosphere etc. Detection and discrimination of objects or surface features means detecting and recording of radiant energy reflected or emitted by objects or surface material Fig.

Different objects return different amount of energy in different bands of the electromagnetic spectrum, incident upon it. This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information.

Remote sensing images are representations of parts of the earth surface as seen from space. The images may be analog or digital. Aerial photographs are examples of analog images while satellite images acquired using electronic sensors are examples of digital images. A digital image is a two-dimensional array of pixels. Remote sensing is a GIS data collection and processing technique. The last two bands image near-infrared wavelengths.

A second sensing system was added to Landsat satellites launched after This imaging system, known as the Thematic Mapper , records seven wavelength bands from the visible to far-infrared portions of the electromagnetic spectrum Figure 2e In addition, the ground resolution of this sensor was enhanced to 30 x 20 meters.

This modification allows for greatly improved clarity of imaged objects. The usefulness of satellites for remote sensing has resulted in several other organizations launching their own devices. Since , SPOT satellites have produced more than 10 million images.

SPOT satellites use two different sensing systems to image the planet. One sensing system produces black and white panchromatic images from the visible band 0. The other sensing device is multispectral capturing green, red, and reflected infrared bands at 20 x 20 meters Figure 2d SPOT-5 has a maximum ground resolution of 2.

Radarsat -1 was launched by the Canadian Space Agency in November, Radarsat is an active remote sensing system that transmits and receives microwave radiation. Landsat and SPOT sensors passively measure reflected radiation at wavelengths roughly equivalent to those detected by our eyes. Radarsat's microwave energy penetrates clouds, rain, dust, or haze and produces images regardless of the Sun's illumination allowing it to image in darkness.

Radarsat images have a resolution between 8 to meters. This sensor has found important applications in crop monitoring, defence surveillance, disaster monitoring, geologic resource mapping, sea-ice mapping and monitoring, oil slick detection, and digital elevation modeling Figure 2e Most people have no problem identifying objects from photographs taken from an oblique angle.

Such views are natural to the human eye and are part of our everyday experience. However, most remotely sensed images are taken from an overhead or vertical perspective and from distances quite removed from ground level.

Both of these circumstances make the interpretation of natural and human-made objects somewhat difficult. In addition, images obtained from devices that receive and capture electromagnetic wavelengths outside human vision can present views that are quite unfamiliar. To overcome the potential difficulties involved in image recognition, professional image interpreters use a number of characteristics to help them identify remotely sensed objects.

Some of these characteristics include:. Shape : this characteristic alone may serve to identify many objects. Examples include the long linear lines of highways, the intersecting runways of an airfield, the perfectly rectangular shape of buildings, or the recognizable shape of an outdoor baseball diamond Figure 2e Size : noting the relative and absolute sizes of objects is important in their identification.

The scale of the image determines the absolute size of an object. As a result, it is very important to recognize the scale of the image to be analyzed. Image Tone or Color : all objects reflect or emit specific signatures of electromagnetic radiation. In most cases, related types of objects emit or reflect similar wavelengths of radiation. Also, the types of recording device and recording media produce images that are reflective of their sensitivity to particular range of radiation. As a result, the interpreter must be aware of how the object being viewed will appear on the image examined.

For example, on color infrared images vegetation has a color that ranges from pink to red rather than the usual tones of green. Pattern : many objects arrange themselves in typical patterns. This is especially true of human-made phenomena. For example, orchards have a systematic arrangement imposed by a farmer, while natural vegetation usually has a random or chaotic pattern Figure 2e Shadow : shadows can sometimes be used to get a different view of an object.

For example, an overhead photograph of a towering smokestack or a radio transmission tower normally presents an identification problem. This difficulty can be over come by photographing these objects at Sun angles that cast shadows.

These shadows then display the shape of the object on the ground. Shadows can also be a problem to interpreters because they often conceal things found on the Earth's surface.