Kowai_wideViewMappazzo recently completed an aerial photo survey study for the Selwyn District Council. Data generated during the mission provide useful data for planning of civil works and ongoing management of the Malvern Hills water race intake on the Kowai River.

The Selwyn District Council was in the process of design for modifications to a section of their water race along the Kowai River near Springfield in Canterbury. After completing a traditional ground survey they were interested in running a trial UAV (Photo Survey) to examine additional details, obtain a high resolution orthophoto and provide a real life comparison of drone based photogrammetry techniques to ground based survey.

Mappazzo used Clarka to undertake a low altitude flight over the area and used the existing survey to georeference the orthophoto and 3D photo survey model. An optimum flight path was identified and programmed prior to the flight (Figure 1) so that Clarka could fly the required course and collect images autonomously. This approach allowed the Mappazzo’s team to maintain a focus on monitoring flight progress and responding to site conditions, and provides optimum efficiency and coverage for the flight.

Clarka covered the surveyed area (approx. 5ha) in a single 10 minute flight capturing a total of 121 images for use in the photo survey. The efficiency of the flight meant that loads of battery capacity remained and the team used some of this to capture video footage of the river and demonstrate some other capabilities.

The resulting data was processed by two different methods to examine the different products that could be generated (at different processing cost). Brief descriptions of the products generated for this project are below.

Orthophoto and Elevation Model

To obtain a georeferenced orthophoto Mappazzo offers a low cost alternative to traditional processing, harnessing the power of “the cloud” to provide an entry level product suitable for most environmental and planning applications. The cost of processing by this method is absorbed into our fees and included in the price of flights.

The orthophoto and elevation model can be hosted online for easy viewing and is available in electronic form for use in GIS or CAD applications. A little additional processing of this data can easily produce contours or GIS features. This product was prepared for the Kowai site to provide an example of base level processing. The low flight altitude and availability of ground control (survey) points resulted in a very high quality product by this method, with pixel resolution of 1.6cm and very good alignment to surveyed features.

An overlay of the traditional survey and the orthophoto (Figure 2) illustrates how well this product can align to known features when processed with ground control.

The output of this initial processing can be viewed online through the following links:

Detailed photo survey processing

More intensive (local) processing was undertaken by Mappazzo to illustrate the full capability of the photo survey method and provide the full range of data outputs available from the survey flight.

The raw output from this processing is an extensive dataset of photo survey “points” (referred to as a “point cloud) that provide a full 3D reconstruction of the site. The point cloud is then processed further to characterise features (ground, vegetation, buildings etc) and create more accurate models of the ground surface and structures.

The point cloud was loaded into 3D design software, used to create a 3D surface model and compared against key cross-sections obtained by the traditional survey method. The results of this comparison proved to be very good with only minor variances between the ground survey and photo survey. View the image via the link on the left to see a cross-section through one of the key earthworks alignments.

There were obvious benefits of obtaining the photo survey for the site as it provided a complete record of the site with wider more detailed coverage of the terrain and major features than the traditional survey method. The orthophoto and 3D models will be used by Selwyn Council and their consultants to identify additional design options and ground features offsite. Noted constraints of the photo survey were the inability to target “covered” objects (such as drain inverts and features covered by dense tree canopy) and the need for ground survey of small objects.

For more information about this project or to enquire about obtaining an orthophoto or photo survey for your site please contact us.

Mappazzo recently had the opportunity to demonstrate the value of UAV video survey for management of parks and reserves. The Grampians reserve in Nelson has areas of very steep terrain which proves a significant access challenge for the reserves maintenance team who are tasked with managing invasive weeds and general upkeep of the park.

Early in December we let Clarka loose to fly over the north western face of the mountain. The raw video footage from the flight was combined with GPS data and other flight information to generate a comprehensive "replay" of the flight.

video survey

View the interactive video survey online (http://videosurvey.mappazzo.com/?video=grampiansDemo)

View large image

The geo-referencing in the video is particularly useful because it allows the maintenance team to go back and identify the weeds and any other features without walking the side of the mountain.The original video footage was recorded in 4k (UHD) quality to give maximum resolution and assist in identifying weeds on the ground. The video survey viewer is setup so users can quickly view a low resolution online version (720p) or select a higher quality file from their desktop. To give you a sample of the product, we've loaded a short 3 min the video into a "demo" viewer.

The resulting product provides a permanent record of conditions at the time of the flight and can be used for future asset management.  We are excited about the new processing workflow that we developed for this project and its other applications, particularly in asset management where we can use video for mapping and condition assessments.

Back in the day our team was responsible for development of a special software product for planning and management of shallow groundwater.

SammEE (Shallow Aquifer Management Model) was developed in 2013 to provide engineers in the Perth metropolitan region with an efficient and more accurate means of predicting seasonal variation in shallow groundwater levels and response the changing landuses. After being used to assess a whole number of sites over the ensuing years it was recently time for SammEE to have an upgrade.

In early 2016 the Mappazzo team completed a comprehensive upgrade which overhauled the user interface and added additional functionality to the analysis and results. Equipped with this new capability users of the software can now analyse different climate scenarios and provide statistical analysis on synthetic rainfall.

Contact us for more information about SammEE or custom software development for your project.

You can also find out a little more about SammEE by reading the initial release notice from 2013.

SammEE in action
SammEE in action