Surveying and Mapping with Your Smartphone
https://www.gim-international.com/content/news/surveying-and-mapping-with-your-smartphone
When we interviewed Professor Thomas Kersten back in 2014, he predicted that the smartphone would become a valuable surveying instrument within just a couple of years – and he was not far wrong! Thanks to the rapid pace of technical advancement, smartphone photogrammetry now enables us to capture reality in 3D. Some smartphones come with a 3D scanning application already integrated, while others can be turned into a 3D scanner by simply downloading an app.
………….smartphone photogrammetry now enables us to capture reality in 3D.
And who knows what the next few years will bring. Will we soon see smartphones equipped with a Lidar sensor – a 3D laser scanner in your pocket? At ‘GIM International’, we’ve put together an overview of the broad range of relevant functionalities already offered by today’s smartphones. Smartphones are omnipresent, and many people can no longer do without them. Smartphone cameras capture images suited for generating point clouds and 3D models. Apps running on smartphones and software running on a remote server enable easy 3D modelling from multiple images. The challenge is to train and guide laymen through a proper image capture strategy using their smartphones
Read on to find out how you can use your smartphone for a multitude of surveying and mapping applications. Some information/extracts/examples are given below:
1. Land Administration
The use of community participation, mobile technologies and cloud storage services could create a new way of undertaking land administration activities, and ultimately lead to more secure land rights for all. Sparked by these grand visions – which were first promoted by Robin McLaren, amongst others, in the late 2000s – alternative land administration platforms are now emerging, such as cadasta.org, landmapp.net and mobineo.org to name but a few.
In a fit-for-purpose approach, boundaries of parcels are identified in the field and drawn on plots of orthophotos using locally trained technicians. The approach is highly participatory. It has previously been implemented in countries such as Rwanda, Kyrgyzstan, Ethiopia, Lesotho and in some Eastern European countries. …. The use of smartphones, which are widely available in Africa, provides a unique opportunity as a fit-for-purpose process is possible without the need for a CLS to acquire extra equipment. Furthermore, while the approach used by conventional surveyors only registers the coordinates of the corners of land boundaries, this approach is suitable for mapping irregularly shaped farmlands.
(Orthophoto based – photogrammetric survey with comprehensive LIS under BhuBharathi was successfully done for 6000 sq km in Nizamabad Distrit in 2008 at a cost of about Rs 200 per hectare involving private companies - Editor)
With the growing mix of off-the-shelf and made-to-order land administration app offerings, the land sector and land professionals have an increasing number of options when undertaking the fit-for-purpose or pro-poor parts of their work.
2. Precisely Flexible Positioning
Pay-as-you-go Software-defined GNSS
………..Even in good conditions, achieving an accuracy of better than one or two metres is beyond the capability of consumer-style phones or tablets. Higher accuracy can increase the performance – and value – of location-aware applications, but the costs and complexity of high-accuracy GNSS solutions have presented barriers to entry for many potential developers and their customers….. With Trimble’s Catalyst, users can obtain positions in real time with accuracy ranging from metre level down to two centimeters……….For years, professional-grade GNSS hardware has come at a price point that has limited access to high-accuracy positioning. But with Catalyst, cost is no longer a barrier to entry to those wanting to add GNSS to their workflows. By shifting the emphasis from hardware to software and cloud-based services, Catalyst is positioned to bring new users to the GNSS arena
3. Bluesky Uses Mobile Phones to Create 3D Maps
Aerial mapping company Bluesky has completed a research project backed by the UK government’s innovation agency, Innovate UK, to develop the use of mobile phones for capturing accurate 3D spatial information. The nine-month investigation focused on the use of standard smartphone technology to capture and calibrate video footage, then convert it to 3D information. Accurate measurements of essential infrastructure, such as overhead power lines and other utility facilities, could then be extracted using specially developed algorithms and workflows
Aerial mapping company Bluesky has completed a research project backed by the UK government’s innovation agency, Innovate UK, to develop the use of mobile phones for capturing accurate 3D spatial information.
The nine-month investigation focused on the use of standard smartphone technology to capture and calibrate video footage, then convert it to 3D information. Accurate measurements of essential infrastructure, such as overhead power lines and other utility facilities, could then be extracted using specially developed algorithms and workflows. Designed to provide an accurate record of the feature’s location and its environment, the Bluesky project is expected to appeal to electricity Distribution Network Operators (DNO) and other organisations with a dispersed asset base, as a low-cost measurement and auditing tool.
4. Point Clouds from Smartphones
Cheap and Rapid 3D Modelling
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Images and videos captured by smartphone cameras can be processed by pipelines running on a remote server. This puts easy 3D modelling from multiple smartphone images within reach for applications such as 3D documentation and modelling in cultural heritage and the creative industry. Disaster management may also benefit from this approach for documenting, monitoring and inspecting hazardous environments.
5. Heritage Sites
Six off-the-shelf Android smartphones captured single or multiple video streams (Table 1) of three cultural heritage sites. Each site was captured by three smartphones by different users to simulate a collaborative 3D documentation approach. The first site, the ‘Saranta Kolones’ monument at Paphos, Cyprus, measuring about 16m x 16m x 5m, is on the UNESCO World Heritage list. The dimensions and complexity are major challenges. The videos were taken throughout the day resulting in varying lighting conditions (Figure 2). The second site was the north-facing façade of the cathedral on ‘Piazza Duomo’ in Trento, Italy, which has a length of 100m and a height of 30m (Figure 3). The third site was the south-facing facade of a painted building measuring 30mx15m and housing ‘Caffe Italia’ in Trento. These sites were simultaneously captured by three collectors (Figures 2 to 4). Challenges of these sites were the flat geometry of the facades and the presence of people, cars, trucks and other moving objects.
For the ‘Saranta Kolones’ dataset, 176 images were captured; it was possible to achieve a final root mean square (RMS) error better than 5mm computed on 20 checkpoints. For the ‘Piazza Duomo’ and ‘Caffe Italia’, 359 images were captured; comparison with 18 checkpoints resulted in an RMS error better than 10mm
Polygon-based rather than boundary-based
The data collection method is ‘polygon-based’ rather than ‘boundary-based’ (Figure 3). The collected polygons with associated attributes are considered to be ‘evidence from the field’. Data collected from the field can be processed and handled in a (cloud-based) geographic information system (GIS), where the collected polygons can be superimposed onto the imagery. Between the polygons, the boundaries will be visible as objects in most cases: fences, hedges, trees, ditches, roads, etc. If those visible objects are not spatial units in themselves, the boundaries can easily be vectorised today and in the future it may be possible to conduct automatic feature extraction. Topology can be introduced if needed.
Imagery is loaded in advance. Most boundaries are clearly visible on aerial photos or on satellite imagery. This imagery should be ‘ready to go’, with proper cache levels, scales, formats, etc. ………………… enabling everyone to follow the process remotely – this is important for the involvement of stakeholders who cannot be on site – and it is possible to set up transparent access to this cloud environment. Usual procedures, such as public inspections,
Bluesky using mobile phones to capture geospatial data
sparse point clouds of Saranta Kolones (coloured) generated from the three smartphones; grey inidcates the entire point cloud.
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