precision survey using drones

PPK Precision Mapping for Construction and Development

Queensland Drones specialises in professional drone topographic mapping for building, construction and development projects. In a market where most operators have no formal training and provide generic cloud-based ouputs with no real value and no real understanding of the havoc they can create for clients, Queensland Drones are the aerial photography specialists with GIS-grade data capture and in-house professional photogrammetry processing delivered by trained GIS specialists.

Our aerial mapping services use survey-grade ground control and industry-standard error management workflows to produce the best possible site contour surveys and ESRI data sets every time. For maximum survey-grade precision we can work hand-in-hand with your preferred surveyor.

Our aerial photogrammetry surveying service gathers georeferenced images for construction and development projects in a fast, efficient, safe and cost-effective way.   Compared to ground-based surveys, aerial mapping with drones can be 4-5 times faster and much safer. 

As a professional aerial mapping company, we work with surveyors, architects, building designers and other professionals to provide a broad range of aerial survey mapping using drones including:

  • Drone mapping prior to commencement of construction
  • Identifying terrain and topographical mapping features
  • Creating planimetric feature maps of existing buildings and structures
  • Precision elevation, contour and topographical surveys to 6cm x/y and 9 cm Z accuracy
  • Volumetric measurement of cut and fill areas for earthworks
  • Hydrological analysis of water flows and water retention
  • Mapping and analysis of vegetation on site and surrounding the site
  • Record of construction and development over time

We are not surveyors, but our precision GIS-grade mapping ensure that architects, engineers, developers, surveyors and builders can use our drone mapping survey outputs to reduce both the time and cost of collecting accurate high-resolution data for large sites. We use precision PPK GNSS survey equipment to ensure precision placement of ground control points and precision geolocation of aerial imagery. Our GIS specialists ensure accurate interpretation of georeferenced data is translated into precise aerial mapping products.

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Our aerial survey mapping outputs for building, construction and development professionals include:

Drone Topographic Mapping to a Georeferenced Orthomosaic Image

Queensland Drones generates a high-resolution TIFF file for drone surveys created by stitching together hundreds of images captured in an aerial drone survey and levelling them based on precision ground control points captured in the aerial photogrammetric images. The TIFF file is georeferenced based on the GPS information in the ground control point files, not the data from the UAV images which can be inaccurate. We typically use a projection based on the WGS84 or GDA94 geographic coordinate systems, but we can also use other projection systems and local planes if required.

Coal Mine Ash Pit Orthographic

The orthographic image is created by accurately stitching hundreds of aerial photos captured using drone topographic mapping

The geoTIFF orthomosaic image can be opened in GIS software like QGIC or ARCGIS and overlaid onto other spatial layers including satellite images and street maps. The GeoTIF can also be imported into AutoCAD using Civil 3D and used as background to design models.

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Digital Surface Model – DEM, DSM or DTM

The point cloud developed through drone surveys to generate the orthomasaic image above can also be used to develop a digital elevation model (sometimes called a digital surface model or digital terrain model which normally includes removal of all elevated structures and vegetation) providing a topographical view of the survey area including any buildings or other structures, natural vegetation, obstructions, etc that may exist on the survey site. The point cloud is based on very high resolution imagery (20 megapixel, with a ground sampling distance of usually <2 cm per pixel) and each pixel in the image set can be translated into both a georeferenced location and an elevation or height. As with the orthomosaic image, the DEM is a georeferenced output that is projected into a standard plane, usually WGS84 or GDA94 for geographic coordinates and NAD83 or GeoID for vertical coordinates.

Coal Mine Ash Pit DEM

Digital Elevation Model represents the heights of terrain across the area

Because Queensland Drones uses surveyed precision ground control points, our DEM coordinates are often accurate to less than 0.15 cm horizontal and less than 0.25m vertical, so they can be used for construction design integration. Queensland Drones can also classify the DEM to effectively remove all trees, buildings, other structures and obstructions in the point cloud and render a DEM of the bare earth for site redesign.

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Contour and Elevation Map from Drone Topographic Mapping

The DEM data developed for the above outputs can be rendered as precision contour maps, much like a topographic map from drone surveys but in a form that can be overlaid onto many other geo-referenced data types. Each line in the contour map represents a set elevation over a section of the site. New lines represent a change in the elevation equal to the contour separation provided.

Drone topographic mapping can be used to measure against as-built design data

The contour and elevation map shows drone topographic mapping data at intervals down to 0.25m

Queensland Drones uses precision ground control points (represented above as green discs) to orthorectify the underlying data behind the stitched imagery, so we can generate contours at intervals of 0.25m, 0.5m or 1m for incorporation into design systems and design drawings. The precision of these contours can be as good as 1-2cm horizontal vertical. These contours can delivered as SHP shape files and/or as KML/KMZ files, or as DWG/DXF/CSV data files. To find out more about how our Drone Surveys and Aerial Mapping Services can benefit your projects, give us a call on the number below, or use one of the other links to request a quote or a callback, usually within one working day.

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TIN and Mesh Model

The high density 3D point cloud data developed from the orthogrammetry can be used to generate a Triangulated Irregular Network (TIN) representation of the continuous surface consisting entirely of triangular faces, each representing the connecting between points in the sparse cloud. This model is sometimes also called a 3D Mesh and is often used to calculate engineering grade DEM data in XYZ data point format, for example.

Coal Mine Ash Pit TIN Mesh

The TIN Mesh or 3D Mesh can be used to create a DEM based on an analytical algorithm

Although we can generate a DEM from the orthogrammetry, the process of thinning the point cloud and triangulating the connections network to generate a TIN model allows for the generation of a DEM which represents only the points necessary for accurate representation of the terrain.

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As Built vs Design Comparison

Because all of our data can be exported to BIM, CAD and GIS platforms, it’s very easy to compare the original design drawings (often in CAD, DWG, DXF or similar formats) to the orthogrammetric imagery, to the contour model, to the TIN mesh model or any other representation of the site.

Drone topographic mapping delivers incredibly detailed TIN and Mesh outputs

The original design drawing can be overlaid on any aspect of the aerial imagery for comparison and measurement

This method allows precise comparison and measurement of the as-built terrain against the design drawings to calculate error, variance and progress to date.

Talk to us now about your requirements

Queensland Drones has extensive experience in orthographic, orthogrammetric and general terrain, elevation and drone topographic mapping using aerial imaging or Lidar data. Give us a call to discuss the requirements of your project and see how our services can save you time, money and effort without compromising project standards and outcomes.

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