What is GPS Survey and How does it Affect the Field of Surveying?
GPS Survey – An Introduction
The term “Survey” has different meanings in different contexts. It may refer to the study of opinions of people about any item or service or may refer to “Census,” too. Though there are different types of surveys, the term is most commonly used to refer to measuring a portion of land so as to present data relevant to the area. This data is then used for different end uses, such as constructing a building. There may be several objectives of land surveying. The person who conducts survey of a particular area is called a surveyor and has to undergo training to understand how to survey any piece of land.
Normally, a survey involves several people who use mechanical and electromechanical equipment that help them in measuring and collecting data about any piece of land. This equipment may include a compass, measuring tapes, calculators, and much more. The precision of data in a survey depends on the area of the land under survey. Line of sight also plays an important role in traditional surveys as most of the measurements are manually done.
Most of the difficulties, costs, and errors are eliminated when surveyors use GPS in surveys. (The linked article describes how GPS plays a role in determining and mapping terrain.) With the easy availability of GPS handhelds, surveyors now use GPS survey equipment, which eliminates the need for several people while also replacing the traditional equipment that often produce erroneous results if not maintained properly. For example, before using a compass in a land survey, you need to make sure that the needle is not subject to friction. If it is, then it won’t be showing the right direction!
Surveyors need not wait for good weather when they are employing GPS in survey as “line of sight” has no role when the survey is dependent on GPS. Data is obtained directly from satellites and the GPS survey equipment does the necessary computation reducing error possibilities to minimum.
Depending upon the objective of GPS survey, a surveyor can select from the different types of GPS survey equipment available. Normally, the GPS survey equipment are the same as any other GPS handheld except that they should certain features pertaining to surveying, such as obtaining signals from 2 or more satellites at a time.
Facilitating GPS Survey – Things to Consider When Buying GPS Survey Equipment
One of the best thing when you use GPS survey is that you need not check out the inter-visibility among the different points where the measurements are to be recorded. Traditional methods had to keep the instruments in such places where the one person (at a distant point) can view the other person (from where the distance was to be measured, for instance) so that the equipment could work properly. This required designing the project in a way that nothing gets in between the two points. With the GPS, the GPS survey equipment can receive signals and hence, positional data, directly from GNSS satellites. This eliminates the need for extensive designing.
Though a design is still required in GPS survey, it is more optimal as you do not have to use too many points for measurements and you can select the most optimum points irrespective of the terrain. This is the basis, basics, advantage (or whatever you may call) of GPS survey.
However, to achieve this, you need to focus on GPS survey equipment that is designed to obtain proper accuracy of GPS irrespective of signal strength. One such GPS instrument can be the one based on WAAS principles. There are plenty of GPS devices available that are capable of enhancing the noise to signal ratio thereby decreasing error probabilities.
Another important thing in land survey is the position of the point and its elevation. This means you need a GPS device that can get data about all three planes in Physics (X, Y, and Z planes). This in turn requires a GPS surveying equipment capable of receiving 3D information from the satellites.
The accuracy of GPS and reduction of GPS measurement errors is yet another factor to be considered for GPS surveying. The reduction of errors can be achieved by receiving signals from at least two satellites – received and computed by two receivers – for determining the average. It is clear that the GPS survey equipment with two receivers will be able to offer greater accuracy of GPS data for enhanced precise surveying results.
Among other factors are the memory considerations, warm-up time, and operational ease of the GPS surveying equipment. As there are no standards set for GPS survey as of now, surveyors can go shopping on the Internet to find the GPS handheld which serves both as a personal gear plus as useful GPS surveying equipment that falls within their budget. (The linked article contains reviews of three most popular GPS handhelds that also double up as GPS surveying equipment).
This post is part of the series: Application of GIS in Geological Mapping - GPS and Surveying
This article series offers information on the applications of GIS in Geological mapping. It also covers GPS in surveying. Surveying using GPS is now easier than manual methods. This series aims to shed light on GPS surveys while also discussing some GPS survey equipment.