As an example, advances in data capture have been around for a while. It is only very recently that some of the implications of accurate positioning technology have begun receiving attention. One problem with more precise data capture tools is that the new datasets they create then need to be integrated with existing datasets, which were captured using less accurate techniques.
Many cadastral databases have this problem. In the past, cadastral data was collected using conventional surveying techniques. Other organisations have, in turn, overlaid their own data on this original, and usually inaccurate depiction of the real world, but surveying techniques have advanced since then. Satellite positioning now gives pinpoint accuracy of a feature’s true location. The original cadastre can then be updated to reflect this more accurate depiction.
There are compelling reasons why asset owners might value a more accurate cadastre. In any situation where the position of the asset is defined relative to the cadastre, inaccuracy in the cadastre delivers an incorrect position for that asset. This can result in non-compliance with legislation that requires organisations to know where their assets are for health and safety purposes.
Problems can arise in maintaining the infrastructure supported by those assets since any incorrect positions have to be fixed. It could also result in legal action being taken as a result of preventable mistakes.
This situation raises a number of, until now, unanswered questions: How can organisations move the original positions and features in their datasets to take advantage of improved accuracy? How can they cope when features have changed or disappeared, or new features have taken their place?
To address these issues 1Spatial has developed a solution. The Radius Align tool has been designed to enable the automatic shifting of asset layers as the underlying cadastre shifts. 1Spatial has previously worked with customers in Europe and North America to address this problem and has now produced a product for the Australian market.
Radius Align uses a predefined set of link files that articulate how two cadastres have shifted. It then applies those link files to assets layers, resulting in savings of time, money and inconvenience. See the figure for an overview of the first stage.
The approach follows two key principles: automation and ease of use. As a result, the complex processing involved is hidden behind a simple and easy-to-use interface. This ensures that users can perform an asset layer shift in three simple clicks. They do not have to be GIS or programming experts to use the tool, as manual intervention is kept to a minimum.
The process is as simple as selecting the layer to be shifted, the link file that is to be applied and a destination file for the shifted layer. The tool can shift data in Shape, Tab or Oracle formats, enabling single or multiple data layers to be shifted at any time.
Although simple in its design and usage, the tool uses a complex mathematical approach. A piecewise triangular warp (Delaunay) creates a triangular mesh from the shift vector data. This is where shift vectors may exist, or where they can be created. The transformation takes place between the triangles, meaning movements to control points within a single triangle have no effect on control points in adjacent triangles. This therefore delivers smaller, more accurate transformation. It also means that nearby coordinates have a much more significant effect on the transformation. The solution is therefore very localised and relevant to the cadastral shift that is required.
Until recently the task of accurately matching these datasets was a manual process and was therefore very expensive. It was also susceptible to error rates of up to 20 per cent.
This manual process involved a detailed comparison, using mathematical theorems, of the original mapping, and then creating a relationship with the corresponding feature in the new data. Once this relationship was recognised a shift vector link file was produced.
The cost was substantial. Until now there has been no software that automated the process. This has been partly due to the complex nature of producing link files that enable the data to be ‘shifted’ to the true position.
The new product is part of our 1Spatial Radius suite; another in the suite, Radius Studio, can be used to automatically create the link files.
This can either be done by a user of Radius Align, or by the data supplier. Crucially, end users are given the means to implement the shift against their own datasets and the base mapping. Using the software in a continuous way can help maintain data integrity and quality.
Radius Studio not only enables the creation of the link files, but also allows the end-user to define a set of quality standards to which the shifted data needs to conform. This can be used to maintain complex relationships between different asset layers – or between an asset layer and the base cadastre itself. This post-shift process ensures the long-term maintenance and quality assurance of the data and because Radius Studio uses rules-based processing, it again is an automated process.
Owing to the use of the open source Feature Data Objects (FDO) data translation tool, accessibility to data is also a simple process in Radius Align. FDO is multi-formatcompatible, allowing connection to industry-standard spatial databases and GIS tools, resulting in reduced data translation costs.
Radius Align is a simple, easyto- use solution that can assist your organisation with its data realignment strategies. You can also benefit from the latest cadastral information available now in the Asia Pacific region to optimise your business operations and customer service.
Key Features
Easy to Use Interface
The product has a simple interface that
is targeted at all levels of users, making
it straightforward and easy to use. The
shifting process can occur in three
button clicks, enabling organisations to
give this task to a wider range of staff
without the need for sophisticated skill
levels or extensive training.
The system will recommend the batching of large amounts of data into manageable files for efficient production. The process should never overburden the hardware performing the shifts so performance for other tasks should not be jeopardised. Data production will be optimised based on the performance of the hardware, making shifting as economical as possible. Feature Data Objects (FDO)
Through the use of the open source FDO data translation tool, Radius Align can not only shift data in Shape, Tab and Oracle formats but also can be expanded to connect to most industrystandard spatial databases and GIS application formats. Shift History
Each data record (or batch) will be time stamped with a text record. Each text record contains information regarding when and where the data was shifted. This allows a data manager/officer to keep track of the data and what has been shifted. By comparing records of comparable shift batches users can monitor and maintain consistent performance, intervening to make improvements when required. This also adds traceability to the process when trying to understand data issues.
Chris Wright
is a managing consultant at 1Spatial. For
further information on Radius Align, visit
www.1spatial.com
This informaiton has been supplied by 1Spatial and its inclusion has been paid for.
