GIS-Based 3-D Analysis & Visualisation Tools: An example in Advanced Planning for Mine Closure
The application of 3D mapping technology can be a valuable and powerful tool to communicate potential mine closure designs to non-technical people and an important step in the mine closure planning process.
With assistance from Sinclair Knight Merz (SKM), Rio Tinto Coal Australia (RTCA) applied 3D Analysis and Visualisation Tools as part of a communications package of proposed mine closure outcomes to government authorities and external stakeholders, including local communities.
The project utilised the intuitive nature of the 3D spatial format to provide a “Visual Spatial Hub” to bring together data from designers, mine planners and environmental scientists to allow critical evaluation of the proposed mine closure outcomes, in a virtual 3D environment.
The two-step process involved analysis and visualisation.
The power of spatial analysis was used to derive data for mine closure planning tasks, for example, the classification of post mine land use. A spatial analysis was conducted to determine the slope angles of the proposed final landform. Classification of slope analysis into categories appropriate for post mine land uses such as grazing, forestry and natural revegetation gives a tangible and spatially accurate output that can be used to assist with native vegetation decision making.
Visualisation is a method for delivering the virtual 3D environment to multiple end users, both internal and external, on standard personal computers with commercial-off-the-shelf or “COTS” hardware and software and without the requirement for specialist skills to operate.
The result is a range of scaleable and customised products that include Perspective Views (static shots of the virtual 3D environment), Multi-media Animations (3D fly-throughs or walk-throughs where the user is taken on a pre-defined route through the 3D environment) and Interactive Visualisation Clients (customised desktop applications where the user can control the way they navigate through the 3D environment).
In the Hunter Valley South pilot, data was collated on the proposed final landform developed with considerations of mine closure outcomes and integrated with existing GIS data such as topography, photogrammetry and infrastructure survey. A virtual 3D Environment was then constructed and delivered to a variety of technical professionals for review.
The intent was to use Perspective Views in the reports to government authorities, as an illustration and support of the report text. The interactive application would then be available for navigation during meetings between RTCA and the authority.
The review step triggered queries of the proposed landform design. The result being the interactive application became part of the landform design process by effectively and intuitively communicating internally the proposed post closure outcomes and facilitating revisions and improvements to the landform design itself.
The primary step in the data manipulation process was the development of Digital Elevation Models (DEM) or terrain models. DEMs were created for both the current landform (from photogrammetry derived data) and for the ‘final’ or post-closure landform, in this case 2029. Elevation models are crucial as they form the basis for all analysis and any errors introduced at this stage would compound throughout the process. A robust technical review by a leading spatial analysis practitioner ensured quality control in this process.
Various analyses can be performed once the data has been collated, manipulated and a DEM produced, depending on the individual needs of the project. These can include slope and / or aspect analysis, visibility or view-shed analysis and change detection. In this case, the value of slope analysis was identified as a mechanism for classification of future land uses in the post-closure landscape. The DEM created from the preliminary 3D design of the post-closure landform was analysed for slope and the resulting raster classified into potential end land uses based on ranges of slope.
Although the classification of slope was useful, by just viewing the resulting slope analysis raster it was difficult to understand how the landscape would change from how it currently looked. A technique known as change detection was suggested by Spatial Analysts at this time.
In order to determine the change in terrain from the present to the post-closure scenario, a change detection between the land form DEM as it exists currently and the DEM based on the post-closure landform design was built. The two DEMs were compared using ERDAS Imagine software to calculate quantitatively the change in elevation between the current and post-closure scenario. The resulting change detection raster was classified into areas of net increase (green) and net decrease (red) in elevation.
An essential objective that needed to be met was the presentation of analysis results in an intuitive and interactive format for ease of communication both internally and externally. Spatial Analysts utilised the power of the 3D spatial format to bring all data types (both raw and analysis results) together for viewing and, more importantly, critical evaluation by Mine Planners and Environmental Scientists.
Good solutions require a delivery mechanism that can ensure the results are available to all decision makers. In this example, a web-like (HTML) interface was created to allow the complex interplay of software, file structure and client to be easily operated by the user with point and click navigation and with directional prompts. The delivery was deployed via disc due to the large volume of data but could be made available via intranet or internet depending on size.
The advantage of this method over other non-spatially based visualisation techniques is the resulting quality of the outputs in terms of geographic accuracy. Perspective and scale are maintained in a way so they are not in “artist’s impressions’. This adds credibility and transparency to the decision making process.
The result for Hunter Valley South was a 3D resource that supported the early planning for the mine closure process and provided a valuable tool for collaborative design and planning for technical professionals.
© Sinclair Knight Merz
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Who does this affect?
Anyone interested in the use of 3-D mapping in relation to mine closure planning.
What do I need to do?
Be aware of the GIS technology available and its potential positive uses in mine closure planning.
Author: Meg Andrews
Meg is SKM’s GIS Team Leader based in our Brisbane, Australia office. Meg has strong experience in mine geology, modelling and estimating, forestry and GIS.
© Sinclair Knight Merz
Requests to re-publish achieve articles should be made here