The most common method for providing an accurate measured plan of terrain is through the use of standard topographic surveying techniques.
The level of detail provided is only restricted by the amount the client wishes to incorporate, but a typical project might include the measurement and plotting of all natural and man-made features, contour details, sewer culvert and manhole locations, with the inclusion, for example of volumation or land area calculations if required. We have approximately 15 in-house survey crews which are capable in carrying out all forms of surveys, including levelling, topographical surveys, dimensional control, pipe line surveys and rail infrastructure surveys.
The output of today’s field survey is no longer a simple 2 dimensional contour plot. Observations completed in the field with modern surveying equipment are stored digitally for processing by dedicated software. This is capable of manipulating huge amounts of 3-D spatial data quickly into formats that are useful to architects, engineers and other design disciplines.
The surveyor has the ability to create a digital terrain model (DTM) from collected data. In essence this is a spatially correct computerised representation of a site. As such, things can be added, overlaid or manipulated and dimensional information can be directly queried. The DTM is thus the starting block for any subsequent design project and can form the base information for many land and industrial GIS applications.
By generating surfaces within the DTM volumetric information can be obtained. Questions concerning quantities such as cut & fill can be answered quickly and accurately. Laborious calculations, traditionally done by hand, can be performed many times at high speeds. This enables the designer to try out more options, giving greater flexibility and ultimately a more cost-effective solution.
Aerial photography can often be the preferred method when considering a survey of large, complex or inaccessible areas of terrain. The resulting images provide the basis for a calculation of the shape and size of terrain and the position of objects at ground level. The scales of mapping produced from the resulting aerial photographs can vary, from small scale maps of 1:50,000 to large scale engineering maps of 1:500, often used when considering the location for a new development, or when designing a route for rail, road or pipeline projects.
Whether a survey is required for planning purposes, route design, volume calculations or simply to update existing mapping, an aerial survey will provide a solution that combines high precision and cost effectiveness.
Aerial surveys provide the following benefits:
- Non intrusive surveying
- Provides usable and flexible 3D data
- Provides photographic records
- Cost effective
A survey can provide all or some of the following:
- Maps up to 10x enlargement from the photographic scale
- Rectified photography and orthophotography
- Archival photographic records
- 3D modelling & visualisation
Whilst aerial photography for mapping purposes is usually taken with a large format aerial survey camera in a fixed wing aircraft, a smaller format survey camera mounted on a helicopter can also be utilised. This can be used in situations where the use of a fixed wing aircraft would be uneconomic or larger scale photography is required.