Basics Of UAV Photogrammetry And LiDAR Mapping

Photogrammetry And LiDAR Mapping

The use of land surveying drones in industries such as mining and construction is still limited, as developments clash with legislation, but there is no doubt that these UAVs can have a big impact on the workflow, efficiency and cost-management of that company.

There are many benefits to be gained from using GPS-equipped drones with the capability to offer photogrammetry and LiDAR mapping.

Before companies can do so, they must first get a better understanding of what this technology is, what it can offer within their industry and the options available.

UAV photogrammetry

The term photogrammetry is one that many people will not have come across because it is a very specialised science. It is, however, something that many industries can take full advantage of.

It is all about making measurements and scale representations from photographs. A camera on a drone can use 3D scanners, UAV LiDAR and other photographic technology to create a 3D model of the given area.

Pointed down at the ground from above, this means a large map of an area of interest for miners, a representation of land mass at a landfill and so much more.

Highly accurate images are made possible through these LiDAR scanners that can see through vegetation and capture 10-80 points per square meter. This technological advancement provides clearer images than have ever been possible.

The industries that could potentially benefit here are vast and the list is sure to continue to grow. They include:

• Oil and Gas Exploration
• Quarries and Mining
• Archaeology
• Forestry Management and Planning
• Urban Planning
• Coastline Management
• Transport Planning

Getting the best results with UAV photogrammetry

Some companies may believe that they can strap any sort of camera onto a drone and get some great aerial footage to aid their objectives. While it is true that any aerial image is better than none, and a drone will always give a great angle, it pays to use the best equipment possible.

There are plenty of interesting amateur videos that have been taken with a GoPro and a steady hand, but this is only really suitable for the hobbyists. If you want the clear images and precision needed for high-end industrial needs, you need a high-end model.

It is important to start with the camera because this is the tool taking the photos that the software then has to work with. The better the image, the better the potential for strong image creation and 3D mapping.

A high-resolution image with the highest megapixel count possible is a building block for sharper and more detailed maps. It can also help to shoot in RAW.

Ideally, the camera should be taking an image every 2 seconds to create a full picture of the landscape and the drone needs to be equipped with an intervalometer. This tool triggers the shutter at the right time.

A great way to approach photogrammetry as a newcomer is to think of it in much the same way you would photography: if you know how to get a strong sharp image with a camera in normal circumstance apply that to the use of the drone.

This means adjusting the aperture to let in enough light, making sure that the lighting is suitable for the image and having a high shutter speed to reduce motion blur.

Of course, much of the creation of these photogrammetry images comes in the editing afterwards. The less that the software has to do the better, so it pays to prepare as much as possible and to delete any images you know the software will struggle with.

In the end, if you haven’t gathered the information in the raw image when that shutter clicks, there is no way for even the smartest software to detect it.

It pays to prepare and ensure that everything will work the first time. If you end up with a frame that is missing or that cannot be used, it is difficult to replicate the precise image on a second flight.

Choosing the best drone for the job

Despite the infancy of many drone-related projects across these industries, there are many diverse products out there that can provide a great starting point for UAV photogrammetry and 3D mapping.

One brand to look into is definitely DJI, as they have a wide range of models with top mapping software, but they are not alone in the market.

Quadcopters like the 3DR X8-M are immediately appealing because they offer a traditional looking drone with simple controls, high-end equipment, and software. This model has a 12MP Canon camera and Pix4DMapper 3rd edition software for creating those 3D maps.

The Aeryon Scout Map Edition Quadcopter, on the other hand, is seen as a professional model with survey-grade accuracy and has the added benefit of GIS Cloud integration.

The eBee is another name that quickly jumps out to companies because it is already being used in trials for industrial use. This autonomous mapping UAV is favoured for its long flight time – with is perfect for large areas – and the quality of its 2D and 3D images.

Simpler models are those that look like model planes and operate via a remote control, rather than autonomous programming.

The 3DR SOLO was designed for GoPro Hero 4 – although its capabilities are expanding – and the 3DR Aero-M actually has similar capabilities as the X8-M quadcopter. These models can be great starting points for those that want quality images will retaining control.

There is potential in use of land surveying drones and UAV photogrammetry across many industries

Creating a 3D map of a large area that needs to be surveyed is a tough job that requires the right equipment and expertise.

The precision of the camera work on these UAVs and the use of 3D mapping software means there is still a lot of surveyors and other operators to learn here, but the use of drones makes the process much more effective and efficient than using planes.

With the right drone, the right software and a good knowledge about aerial photography, it is possible for companies to create detailed, accurate 3D maps full of useful data and to improve the prospects of the company.