What is a point cloud?

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About photogrammetry
Another way to get a point cloud is photogrammetry, a method of determining the shape and size of an object based on its photographic image. Initially, this image is flat, so to create a volumetric effect, the so-called stereo pair, it is taken from different points and then the pictures are combined in special software. Stereo pairs are then used to create a three-dimensional model.

The advantage of photogrammetry is that a point cloud can be created even using a smartphone. However, to do this, you need to know the rules of shooting. However, to obtain data suitable for use in commercial projects, you certainly need to phone number in russia use professional equipment. But compared to 3D scanners, it is much cheaper.


Alexander Korzhov gave his own definition of the term to the BIM breakfast audience:

A point cloud is a set of information about the spatial position and appearance of an existing object in nature, obtained as a result of laser scanning, photogrammetric survey or surveying with a tachymeter.

The expert also noted that point clouds are a collection of both visible and invisible information, the so-called blind spots. These areas are a significant problem, since artificial intelligence cannot recognize a complete object in them due to the lack of information. That is why when processing point clouds, an experienced specialist is required who can competently process the data manually and supplement it if necessary.

Point clouds can be colored or black and white. According to Alexander, the second option is enough for his work - it contains enough information about the geometry and dimensions of the object needed to build a model. Colored point clouds are also in demand, but less so, since they take much longer and are more expensive to create.

On creating facade models from point clouds
Alexander Korzhov once again emphasized that the creation of facade models from point clouds is not much different from the creation of other building elements; the methodology is almost the same.

So, for modeling the main elements of facades, that is, walls, Revit has all the necessary tools. But the functionality of the program also has a drawback: it is impossible to set up non-strictly vertical facades without additional labor-intensive actions. However, Revit still allows you to get information in aggregate: with the number of windows, decorative elements and data on the material.

The expert also added that before starting modeling, he sends the customer a list of questions that help him understand the benefits and purpose of the point cloud and draw up clear requirements for the model.

What's the bottom line?
At the end of his speech, Alexander Korzhov noted that to work with point clouds, you also need to know special software like ReCap and CYCLONE; knowledge of working in CAD alone will not be enough. He also talked about his project to create a knowledge base that helped beginners "not be afraid" of point clouds and learn to confidently process them. So far, it is only in the initial stage of development, but work on its development will continue.