EXPERIENCE & RELIABILITY
What is Geodetic Surveying
Geodetic surveying is the survey in which the curvature of the earth is taken into account and higher degree of accuracy in linear and angular observations is achieved. The geodetic surveys extend over large areas and lines connecting any two points on the surface of the earth are treated as arcs. For calculating their projected distances on the plans or maps, the correction for the earthÃ‚ curvature is applied to the measured distances. The angles between the curved lines are treated as spherical angles. A knowledge of spherical trigonometry is necessary for making measurements for the geodetic surveys.
Why we Need Geodetic Surveying
.Geodetic surveys are conducted with highest degree of accuracy to provide widely spaced control points on the earth surface for subsequent plane surveys. Provision of such control points is based on the principle of surveying from the whole to the part and not from the part to the whole, as stated earlier. Geodetic surveys require the use of sophisticated instruments, accurate methods of observations and their computation with accurate adjustment. To eliminate the errors in the observations due to refraction, angular observations are generally restricted to night and arc lamps are used as signals on the survey stations.
Geodetic surveying can be divided in the following ways:
In this type of surveying a network of well defined triangles are formed on the plot of land to be surveyed. Only one line known as base line and all other angles are measured very carefully.
Â· Reciprocal Leveling
This type of surveying is required to obtain the difference in levels between two points which are separated by obstacles.
Stadia or Tacheometric Surveying
This is a type of surveying in which vertical and horizontal distances are computed from stadia readings without using chain or tape.
Â· Astronomical Surveying
It is a branch of surveying in which the meridian, azimuth, latitude, time etc of a place on the surface of the earth are determined by observation of some bodies like the sun and the fixed stars.
Â· Photographic Surveying
This is a method of surveying in which plans or maps are prepared fromphotographs taken from suitable camera stations.
3D laser scanner
Underground Utility survey
The techniques used to determine the subsurface utility is Ground Penetrating Radar Method & Radio Detector Method. GPR uses high frequency electromagnetic waves to acquire subsurface information. Energy is radiated downward into the ground from a transmitter and is reflected back to a receiving antenna. The reflected signals are recorded and produce a continuous cross sectional or Profile of shallow subsurface conditions, Reflections of the radar wave occurs where there is a change in the dielectric constant or electrical conductivity between two materials. Directly over the conductor and this position or series of positions can then be marked on the ground. These positions can then be rapidly coordinated using either tachometric observations (total station) or kinematic observations (GPS) and the data recorded and downloaded for computation and production of drawing files.
What we use Underground Utility survey for
Radiodetection techniques are unable to detect non-metallic buried services such as plastic water and gas pipes, fibre-optics and drainage pipes that we cannot introduce a sonde into. To overcome this potentially hazardous situation, we combine the use of Radiodetection with Ground Penetrating Radar (GPR).
GPR is able to detect non-metallic as well as metallic pipes. It will also give an indication of the location and depth of buried services but will not identify them.
Changes in conductivity and in dielectric properties are associated with natural hydrogeology conditions such as bedding, cementation, moisture, clay content, voids and fractures. Large changes in dielectric properties often exist between geologic materials and man-made structures such as buried utilities or tanks. The Radio Detection instruments are used to point the subsurface utility accurately. For the most reliable determination of position, the optimum method is to clamp the Frequency Unit on to an exposed pipe or cable whereby signals then transmitted along the utility and can be detected by receiving unit A maximum signal is returned when the instrument is located directly over the conductor and this position or series of positions can then be marked on the ground. These positions can then be rapidly coordinated using either tachometric observations (total station) or kinematic observations (GPS) and the data recorded and downloaded for computation and production of drawing files.
Soil investigation and material testing
Geotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions. This type of investigation is called a site investigation. Additionally, geotechnical investigations are also used to measure the thermal resistivity of soils or backfill materials required for underground transmission lines, oil and gas pipelines, radioactive waste disposal, and solar thermal storage facilities. A geotechnical investigation will include surface exploration and subsurface exploration of a site. Sometimes, geophysical methods are used to obtain data about sites. Subsurface exploration usually involves soil sampling and laboratory tests of the soil samples retrieved.
What We Need Soil investigation and material testing for
PLUMB surveying has a wide range of services for all types of construction materials testing, geotechnical investigation and others.
Geo-technical Investigation up to 100m deep boreholes for shallow, deep and raft foundations
Â· Construction Building Material Testing
Â· Quality Control, Site Supervision and Site Laboratory
Â·Â Concrete Testing including Non Destructive Testing Soil, Rock and Water Sampling
Bathymetry can be defined as measurement of sea depths using scientific methods and technology or the study of underwater lands and their features and shapes. The act of carrying out a bathymetric study on a water body such as a lake, river or ocean is called a bathymetric survey, whose main purpose is to measure the depth of water and the shape the terrain below it. The result of this type of hydrographic survey is a clear and detailed mapping of the land submerged on the water body.
What is Bathymetric Surveys used for
Bathymetry or Bathymetric surveys have several uses and the methods used to conduct them have evolved over time. One of the major uses of these surveys is to have a clear understanding of the terrain below the water bodies. A study carried out on the terrain under a water body floor can help understand the water behavior above that terrain, which is important for academic studies in schools and most importantly for safe navigation above or in those water bodies. This makes the surveys vital for small and commercial use since water is one of the worlds recognized means of transportation.
A good example as to how bathymetry is used for safety is a view of a sea with commercial ships navigating through. The features and shape of the seabed can determine the temperature of the water, speed and other critical characteristics of the water above it. This is mainly because the behavior of a mass of water is highly influenced by these important factors. Since safety is a primary concern during any kind of transportation, captains have to navigate any ship with a clear understanding of how the land beneath the water they are above is like. However, it is worthwhile to note that hydrographic surveys are different from bathymetric surveys since the latter are more detailed than the former. Hydrographic surveys have less details and are, therefore, easy for captains to read through and understand for the navigators.
Over the years, the methods of carrying out bathymetry have greatly evolved from the use of chains being dropped onto the sea until they touch the seabed to the use of GPS and echo-sounders to give a clear 3D representation of the seabed features and shapes. The use of long chains was highly ineffective leading to invention of more effective methods. Use of effective methods of carrying out bathymetric surveys has resulted to more accurate results and with more details pertaining to the land beneath the water and the distance from the water surface.Whereas PLUMB surveying use a great variety of sensing instruments and data may be collected from above or below the Earths surface or from aerial or marine platforms.
Satellite Imagery Processing
An image of a portion of the surface of the earth that is captured by image sensors onboard an orbiting satellite and subsequently transferred to a control station on the ground. Remotely sensed satellite imagery is becoming increasingly common as satellites equipped with technologically advanced sensors are continually being sent into space by public agencies and private companies around the globe. Satellites are used for applications such as military and civilian earth observation, communication, navigation, weather, research, and more. These satellites maintain different altitudes, inclinations, eccentricities, synchronizes, and orbital centers, allowing them to image a wide variety of surface features and processes Satellite Used Digital Globe Ikonos Rapid eye
Why we use Satellite Imagery
In the broadest context, satellite image data can be considered to provide two major uses for assisting human dimensions studies. The first use is as a spatial frame of reference for assisting the planning and coordination of global change research. The second use is as a basis for information derivation through data processing and analytic procedures employed as part of the research methodology. The general distinction made here between these two uses is for the benefit of discussion; in practice the distinction is frequently blurred in the course of the research process.
Use of satellite image data as a spatial frame of reference generally refers to the use of image products that have been prepared to enhance the visual distinction of all, or selected, landscape features. Satellite image products can assist the planning and coordination of global change research by facilitating the design of research strategies and the implementation of methodologies that contribute to a global understanding of human dimensions activities. For strategizing at the global scale, satellite images provide Global Context Information. For implementing studies at local and regional scales, satellite images provide a consistent basis for promoting Uniform Research Methods. For presenting the results of human dimensions studies, satellite images enable the development of useful Knowledge Transfer Products.
Satellite image data offer significant capabilities for deriving information integral to human dimensions studies, especially those concerned with the impacts of human activity on land use and land cover. These data inherently contain information that relates to the type and spatial extent of land cover. The information output of these operations may be useful as a final product or can be entered into a geographic information system (GIS) for subsequent integrated analysis and/or model development with other spatial variables.
Topographic maps show the three-dimensional shape of the landscape by representing equal elevation with lines on a two-dimensional map; they are in essence a type of contour map (also used in meteorology and oceanography). Although these can be mathematically derived, most geologists create them by measuring the elevation (and position) in the field (or on an aerial photo), plotting elevation on a map and connecting lines of equal elevation (much like connect-the-dots except that all the same numbers are connected, rather than in sequence). This module is designed to give you experience examining and reading topographic maps, understanding scale, calculating slope and drawing topographic profiles.
Why we Use Topography images
Topographic maps are detailed, accurate graphic representations of features that appear on the Earths surface. These features include:
cultural: roads, buildings, urban development, railways, airports, names of places and geographic features, administrative boundaries, state and international borders, reserves
Hydrography: lakes, rivers, streams, swamps, coastal flats
Relief: mountains, valleys, slopes, depressions
Vegetation: wooded and cleared areas, vineyards and orchards.
Topographic maps usually show a geographic graticule and a coordinate grid, so you can determine relative and absolute positions of mapped features.
It is important to note that a map is merely a two or three dimensional representation of the physical environment at a given time. Therefore, a map will never be entirely up to date. Changes to the landscape and cultural features regularly occur (such as roads, vegetation, and buildings), resulting in maps becoming dated, although the rate of obsolescence varies depending upon location.
Topo maps provide highly detailed information about the natural and man-made aspects of the terrain, but are best known for their series of contour lines that show elevation changes, and colors signifying varying land types and bodies of water. Topographic maps in their paper form have been in use for many years, and are a mainstay of outdoorspeople and those who must understand landscape details for business purposes.
The objectives of carrying out traffic volume study are designing, improving traffic system, planning, management etc.
Structural and geometric design of pavements, bridge, and other highway facilities; intersection design including minimum turning path, channelization, flaring, traffic control devices viz. traffic signs, markings, signals based on approach volume and turning proportions etc.
To allocate limited maintenance budget rationally; to improve the roadway operating condition; to examine the existing operating/service condition; to determine the type of improvement measure need to be taken etc.
Accurate information on the amount of traffic on the roads is vital for the planning of both road maintenance and improvement policies
Dynamic Traffic Management Purposes: Up to date and continuous flow/congestion information is essential for optimizing; Network productivity by providing information to the road user etc.
Â· Estimation of highway usage
Â· Measurement of current demand of a facility
Â· Estimation of trends
Â· Economic feasibility evaluation
Â· Computation of accident rates etc.
Aerial survey is a method of collecting geomatics or other imagery by using aerial methods. Typical types of data collected are aerial photography, LiDAR, remote sensing (using various visible and invisible bands of the electromagnetic spectrum, (such as infrared, gamma, or ultraviolet) and also geophysical data (such as aeromagnetic surveys and gravity. It can also refer to the chart or map made by analyzing a region from the air. Aerial survey should be distinguished from satellite imagery technologies because of its better resolution, quality and atmospheric conditions. Measurements on aerial images are provided by photogrammetric technologies and methods.
What for we need aerial surveying
I. Construction Sites. The aerial monitoring of construction sites provides new information during all stages of a project lifecycle. The capability to quickly model from above in 3D and greater precision gives a check on projects with as-builts compared to plans. It also provides the better coordination of materials on the job site.
II. Infrastructure Inspection. Drones can hugely improve infrastructure inspection with the ability to sense in three dimensions, take thermal readings, and to detect metal strain. Regular aerial monitoring gives benefits to the inspection of complex infrastructure such as power lines, pipelines, towers, processing plants.
III. Prospecting suitable for mineral, oil and gas exploration, enabling prospectors to extend their tool set with aerial sensors to confirm and expand their insight. Ferrous metals and gravitational fields can be detected with magnetometers on aerial platforms, causing less of a disturbance due to their size.
IV. Environmental MonitoringÃ‚ suitable for monitoring hard to reach areas, or taking reading in contaminated areas where human health would be at risk.
V. Agriculture to provide useful data, such as crop scouting and geo-referencing. They can allow farmers to monitor dispersion of pesticide and usage of fertilizer, as well as to monitor crop health parameters, including soil moisture.