What is a point cloud survey?

Clare Montgomery
Survey Insight by Clare Montgomery Head of Operations 20/11/2012

What is a point cloud survey? At CADS we use 3D laser scanners to capture point cloud data, creating a precise, virtual copy of physical reality


Point cloud flythroughs

An accurate survey is of paramount importance in any construction project. At CADS we use a variety of 3D laser-scanners to capture point cloud data and create a precise, virtual copy of the physical reality.

It’s this virtual copy of reality, rather than the survey data, that gets our customers really excited

It allows the customer to visualise the detail that the scanner captures, they don’t just see a marked-up plan, they see the building in its’ natural state, giving a real snapshot of its’ day-to-day use. This puts the detail into context.

So how do we make the most of this information?

power of data

Creating an animation from a point cloud survey – the recording process

The first thing our survey team members do following a scan is create a point cloud model of the site, allowing us to manoeuvre around it in 3D space.

Our surveyors will then set a ‘clip’ around the model, this ensures that all stray points around the site are eliminated thus focusing on the actual building model.

The next thing to do is to set a starting point where the animation will begin, this is generally a point in the cloud where you can see the entire building. To keep things neat and logical we prefer to start from a point looking directly at the front of the building.

From this point the viewport could be set at eye-level, but a birds-eye-view of the site is preferred to show a larger field of view.

The animation then moves towards the main building / area of interest. This could be the front door of a building or a specific area of interest to the client.

The model is then explored to determine the scope of the building, then a sequence of cameras are set to generate the animation. These viewpoints are saved as camera locations, allowing us to go back to specific sections of the model. Once the cameras are set, a timeline is used to set the key frames for the animation. We find that the more levels there are to the building the more interesting the animation can be. For example, one can move through ceilings with ease, showing areas that viewers would not normally be able to see first hand.

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Animating and rendering the point cloud

Once we have the basic storyboard, the animation is set up for exporting. Rendering out all of the frames is the most time consuming part of the whole process. The application takes a snap-shot of every single frame. The final step is to compile the sequence images into a container format for distribution to the client, this can be done in all industry standard formats and will be greatly influenced by the clients viewing platform. For example, we issue most of our files in a format that is optimised for tablets, so that the file can be shared amongst people with ease.

If you need a point cloud survey, this video shows a recent project involving point cloud data.

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