Photogrammetry 3D scan

  • Class: 3D Scanning
  • Software used: Agisoft photoscan
  • Machine used:  Smartphone camera, Laptop
  • Technics used: Photogrammetry 3D scan

The purpose of the lesson
  • Understand the operation principle of 3d scanning
  • Know what are the methods of scanning
  • Try using one of the 3d scanning methods. It is better if it is used in the city project

First, let’s understand what 3d scanning is all about. Imagine that there is a detail with a lot of complex surfaces, which you can not measure with a standard caliper, or you will have to tinker around for a long time and painfully to get the results of the required accuracy. And then on these data still get a mathematical model. That’s where the 3D scanner comes in. It makes it possible to shorten the production of a mathematical model that is suitable for comparison with the reference model. The use of scanning does not end there. 3d scanning is also used to obtain accurate models of complex objects that can later be used to obtain prototype products, build new products based on existing ones. Also used in the film industry, in medicine, in museum business, in industrial design and in the entertainment industry, for example, when creating computer games. With the help of three-dimensional scanning, one can digitize cultural heritage, archaeological objects, art objects. In addition, three-dimensional scanning has found wide application in medical prosthetics, in digital archiving and so on. Now let’s see what methods of 3d scanning exist.

Currently there are two scanning methods:

  • Active method or scanning with kinect for example
  • Passive method or photogrammetry

The active method is based on recording the reflected rays from the scanning object. The source of such rays is the 3d scanner itself
The principle of this method is based on measuring the distance from the scanner to the points of the scan object. The camera reads the reflections and gets the image of the scanned object by distortion. With structured lighting, the object is illuminated by a certain “pattern” (grid), by distortions of which the camera forms the 3d model. This data is either stored in the scanner’s memory, and then transferred to the computer, or immediately sent to the computer, where they are processed and build a three-dimensional model. Because The 3d scanner at a time sees only part of the object, during the scanning process it is necessary to move the scanning object, or to move the scanner itself. Thus, as a result, we get a model by sewing the obtained pieces of the object.

The passive method uses already existing ambient light. Reflection of this light from the object and analyzed by a 3d scanner. In fact, this method of scanning is either the shooting of an object by ordinary video cameras with different illumination and restoring them in 3d, or shooting the silhouette of an object on a high contrast background using stereoscopic or “silhouette” video cameras.

PROCESS DESIGN
  • I chose the method of photogrammetry. The book was used as an object. And so, first of all I took on the video moving around in a circle at different angles over the object. Further we need to get images from the video at a certain interval. I chose every 10th frame. Open the program Agisoft photoscanner and download received pictures

  • Then align photos, build dense cloud and create a mesh from a cloud of points

  • On the output we get a mesh but still without a good quality texture

  • It remains to cut unnecessary details, build a texture of high quality and can be exported for future use

The method of scanning using kinect you can see and compare in the blog post KAMILIA IUSUPOVA. We scanned the same object

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