Point clouds with drones, the new era of surveying?

Point clouds with drones, the new era of surveying?

Do you get involved in survey works and want to increase efficiency? Keep reading to find out the potential of point clouds with drones, a new technology that is disrupting the AEC industry.

In a previous post we talked about how drones are becoming a mainstream tool for surveyors, engineers and contractors. We briefly touched on the capabilities of drones, including 3D point clouds. However, given the rapid take-up of this technology we’ve given it a post all its own! Less than a decade ago probably nobody would have imagined drones being accessible to virtually everybody. And they are becoming the main tool to obtain all kind of surveys with point clouds!

But what is a point cloud exactly?

It’s essentially a collection of data points assembled in space. The cameras that most professional drones mount these days have incorporated capabilities to take ‘intelligent’ photos. These photos taken with a drone are not just a 2D representation of reality. They also include 3D data associated to the points. From these photos, through a process called photogrammetry, you can obtain a 3D point cloud. For example, it may include coordinates and elevation (X, Y and Z). The points also inherit the colour of the element they represent. Thanks to this, when you assemble your 3D point cloud, it looks just like a picture of the real elements.

Point clouds with drones or laser scanners?

Before the era of drones, it was possible to obtain 3D point clouds with laser scanners, which are still utilised today. The disadvantage of most laser scanners is that they require more setting up time, similar to a traditional theodolite. They also provide more limited results, since they can only capture points that are in their line of sight from a static point. For example, to get the 3D point cloud of a square building, you would have to position the laser scanner on at least 3 different points around the building. This takes significant time as you need to set up the scanner on each of the points. With a drone, it’s far simpler. You just need to fly the drone around the building and that’s it. In a matter of minutes, you can get the entire 3D point cloud.

However, laser scanning is also advancing, with the latest technologies permitting mobile LiDAR. For example, surveys of roads and motorways are these days taken using this method. It is possible to mount the laser scanner on top of a vehicle, à la Google Maps. Whilst driving the vehicle, the laser scans the nearby surfaces to generate a 3D point cloud. This is far quicker than the traditional method of surveying roads and motorways, reducing the overall time from weeks or months down to hours or days.

Advantages of point clouds with drones

But why put yourself and others at risk by driving, if you can just fly? As we said at the beginning of the post, drones are coming to disrupt the industry. You can avoid the intrinsic risk associated with driving which is necessary in mobile LiDAR. You can just position yourself at a safe place and pilot your drone along the road that you want to survey. In a matter of minutes or hours you can obtain enough photos to create your point cloud.

From the point clouds generated with a drone it is possible to extract surfaces, objects, 3D models, plans, sections, etc. Point clouds are data-rich, and you can use them to analyse elevations, distances, volumes and more. They are starting to become the norm in construction sites to calculate cut and fill volumes for earthworks. Architecture companies are also using them to generate quick 3D models of existing buildings. From these, they can generate accurate plan views and elevations. With software like Autodesk ReCap, Revit and Civil 3D, it is possible to combine 3D point clouds and transform the data into pretty much whatever you want.

Will drones replace the traditional survey role?

Probably not. Drones still have some limitations, for example obtaining data through soft elements like vegetation. What drones are doing is to make the surveyor’s life easier, at least when it comes to data collection on site. They won’t need to spend so much time exposed to risks on site. However, the processing time of the data in the office is increasing. Before, the surveyors would code each element on site when they capture points, like top of kerb, back of footway, verge, etc. This coding made the process of putting the information into a CAD software relatively simple. Now, with a point cloud, there is a need to invest more time in analysing the data. For example, if you want to create a 2D plan from the 3D point cloud, you will need to create sections and probably a lot of manual work. Although there is software that’s trying to automate the process, it’s still not perfect, and surveyors will need to amend the outputs to represent reality correctly.

In a nutshell, point clouds with drones are significantly reducing the time to obtain the data on site. It is therefore reducing costs and exposure to risks. On the other hand, they are increasing the desktop-based time to process the data, so there will still be work for surveyors for years to come!

Here at GlobalCAD we specialise in BIM services, and can help you to process the data from your point clouds to transform them into 3D models, plans, sections and more! Get in touch to see how we can help you on your projects!

 

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