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23
Nov

Using metropolitan scale Digital Surface Models for wireless network coverage analysis

The slow propagation of the NBN and the constant demand for high bandwidth services such as Netflix, Stan etc. has created a niche for high bandwidth point to point links and wireless DSL providers. Here are some of their taglines:

“The future’s not faster cables, it’s NO cables” – NuSkope

“Wireless broadband delivers gigabit speeds to residents and businesses now” – Uniti Wireless

“Satisfy your need for speed without the NBN!” – Lightning Broadband

antennas_small

Planning for the point to point links requires detailed knowledge of the line-of-sight since propagation at these frequencies (2.4GHz, 5.8GHz and 24GHz) can be very sensitive to clutter and multi-path interference. Aerometrex provides detailed (50cm cell spacing) Digital Surface Models for Adelaide and Melbourne Metropolitan Area to all the players in the Wireless Broadband segment. We helped Uniti Wireless build a web tool for their customers to analyse the feasibility of receiving a connection as well as an internal tool for planning deployment of new towers.

uniti_clients_blur

Adelaide, Melbourne and Mt. Barker datasets (7280 sq. km., 122GB binary data) were ingested into a PostgreSQL/PostGIS database, indexed and stored procedures built to extract full-resolution transects 10km long in less than 1second. Performing line-of-sight operations requires reprojection to ENU (East-North-Up) projection relative to the location of the tower. Algorithms were built reproject from MGA Zones to ENU per analysis and calculate LoS and Fresnel zones. The availability of the accurate DSM and associated rapid/scalable analysis tools has enabled the wireless service providers to expand rapidly and cover most customers with the most efficient placement of towers.Qgis_viewshed

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22
Nov

Quantitative Coastal Erosion Monitoring using Photogrammetry

Aerial and Ground based Lidar and photogrammetry have been used individually and in combination to monitor coastal erosion. We have developed our oblique photogrammetry with multi-ray matching technique to a point where these methods can be replaced by a single dataset captured using Aero3dpro methodologies. With accurate survey control multiple epochs are exactly aligned and suitable for displacement analysis and volume calculations of material lost due to erosion.

A test site was chosen near Darwin, Northern Territory, Australia. The area known as Nightcliff has been featured in the voyage of the Beagle and is the site on the Nightcliff market of Sundays. Thus the area is of historical and social importance. This area has had a lot of cliff loss due to erosion and a coastal management plan has been put in place to construct a sea-wall along the foreshore. Datasets captured in 2014 and 2016 clearly show these changes and provide quantitative displacements, which can be calculated using Hausdorff distance algorithms on the reconstructed meshes. A plot of the displacement can be seen in the image below.

Nightcliff Displacements

Nightcliff Coastal Erosion and displacements

An interactive model of this area can be viewed in the Cesium viewer below, it also includes Darwin background ortho imagery from MetroMap.

Nighcliff

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