IP-S2 makes short work of QLD flood mapping

Global Infrastructure Surveys (GIS), in conjunction with Rapid Survey Solutions (RSS), used Topcon's IP-S2 to map flood-affected areas in Central Queensland for risk assessment.

Central Highlands Regional Council (CHRC) is based around the town of Emerald, located in central Queensland’s coal-rich Bowen Basin – and one of the regions particularly badly affected by the floods. Mining in the region has still not completely recovered.

The council contracted GIS and RSS to map Emerald so it could extract floor levels for every house for future flood management measures, which involved surveying a total street length of around 450 km.

It is primarily using the data captured by the IP-S2 for risk assessment purposes, allowing it to know where existing house floor levels are for future flood management, as well as planning of new buildings and the floor levels the council would require to minimise the chances of flood damage.

Topcon’s IP-S2 – which is sold and supported in Australia through Topcon’s distributor Position Partners – allows users to map, log and locate all objects along any roadway, rail reserve or construction right-of-way, with accuracies of 30-50 mm, at distances of up to 50 m – all within posted on-road speeds.

The IP-S2, which is vehicle-mounted and works off a standard 12-volt power connection, combines dual-frequency GNSS signal tracking and positioning and inertial measurement to integrate laser scanning and high-resolution digital imaging.

Using laser scanners and cameras, the data collected is integrated and time-stamped, allowing accurate combination of LIDAR point cloud information and digital imaging data, to build 3D models of the areas covered.

In mapping Emerald, the IP-S2 vehicle, driven by RSS co-director Nick Nolan, was able to cover every street in the council’s prescribed area over a very short period, giving the council the ability to capture data on the floor levels of a most houses in the town.

Once the data has been completely processed and analysed, the council will know the floor level of each house within the surveyed area – for example, whether it is a “Queenslander” style house with a raised living area above the surrounding ground, or a more modern design with a concrete slab on the ground, or anything in between.

In addition, CHRC purchased a copy of Topcon’s Spatial Factory, which allows viewing, analysing, and extracting features from processed IP-S2 datasets.

Shortly after the devastating floods hit Queensland, Lyle Harman, the CHRC’s recovery co-ordinator, contacted Les Whalley, managing director of GIS.

“The council was interested in obtaining the floor level of the houses in the affected areas of town primarily to allow better flood management and assessments on how future floods would impact various parts of the town,” said Les.

“The council needed a rapid solution; we’d previously worked in conjunction with RSS and we knew the capabilities of the IP-S2 technology – and so we recommended this system to CHRC.

“Not only was the IP-S2 exactly what they were after, it also saved considerable time and money,” he said.

RSS co-owner Brad Chambers said that CHRC saw potential in the IP-S2 captured data, not only for meeting its immediate needs in post-flood studies of floor levels, but also for the data-mining of information captured for other purposes.

“One of the big benefits that they could see out of this system over any other, was that it was able to generate photographic images as well as three-dimensional survey detail and because the information captured was quite rich, they could data-mine additional information later on – and that was really the key to their deciding to go ahead with it,” said Brad.

“Basically, we left Melbourne on the Friday night, drove up the centre of the country and landed there on Sunday in time to do a reconnaissance mission around the town to work out the best way to attack it.

“We had a base station set up so that we split the town into six areas, of fairly equal size and bounded by a major road, giving us some overlap with the LIDAR data.

“For each one of those areas, we had a base station and recorded all the positions of the survey marks in the area,” he said.

“This involved placing numerous ground control points – something which was far more time consuming than the actual IP-S2 Survey, and which needs to be taken into account on any project requiring tight positional tolerances.

“Each one of those was recorded by GPS base and rover, then later on was imported into Spatial Factory so that we could register all that control in the IP-S2 run; that ensured that we got the accuracy that the council required for level control and position,” Brad said.

For the short period of time the RSS team was in Emerald it collected imagery and LIDAR data for around 450 km of streets. The remainder of data was processed on its return to Melbourne.

According to Brad, one challenge the team faced was situations where houses were behind high fences or trees.

“The problem is that if you can’t see the house, you can’t see the floor level.

“However, we were recording images every 3 metres, which was a lot more than we normally would and that gave us the chance to see up driveways and down in between houses.

“So, if we can actually see the house and the scanners can get some points on the building, we can then interpolate off the points and off the images as to where the floor level would be,” he said.

Once the data had been captured and processed, the council used Topcon’s Spatial Factory to analyse it.

By going through each image and clicking on the floor, its survey team can create points for CHRC’s GIS system.

“Each point has an X, Y, Z position, which effectively gives the council an address for each of those houses; then, once it is in the GIS, it can run a report function on any of the attributes collected,” said Brad.

“That has allowed the council to take the data that we and RSS supplied to them and then process and analyse everything themselves without us having to extract it for them.”

According to Les, the capabilities of the IP-S2 allowed the council to capture far more data, at a far lower cost, than it had originally planned.

“Initially for this project, the council wanted to just map flood-affected areas, but due to the cost-effectiveness of the IP-S2 and its speed of operation, the council was able to map the entire town, capturing data for a wide range of purposes that it can use for many years to come,” he said.

Further information, Global Infrastructure Surveys: Ph 07 5520 3304 enquiries@globalsurveys.com.au