3D reconstruction refers to the process of capturing the shape and appearance of real objects using specialized scanners and software and converting those scans into digital 3D models. These 3D models allow us to represent real-world objects in virtual 3D space on computers very accurately. The technology behind 3D reconstruction utilizes a variety of different scanning techniques, from laser scanning to photometric stereo, in order to digitally preserve real objects and environments.
History and Early Developments
One of the earliest forms of 3D scanning and reconstruction dates back to the 1960s, when laser range scanning first emerged as a method. Early laser scanners were slow and bulky, but provided a way to accurately capture 3D coordinates from surfaces. In the 1970s and 80s, raster stereo techniques came about, using cameras instead of lasers to capture depth maps of scenes. Over time, scanners got faster, accuracy improved, and multiple scanning technologies started to converge into unified 3D modeling pipelines. By the 1990s, digitizing entire buildings or archeological sites became possible thanks to the increased capabilities of 3D reconstruction tools and hardware.
Photogrammetry and Structure from Motion
One major development that helped accelerate 3D Reconstruction was the emergence of photogrammetry techniques. Photogrammetry uses 2D imagery, often from consumer cameras, to extract 3D geometric data. Structure from motion algorithms allow one to take unordered image collections, determine overlapping features across images, and reconstruct the camera positions and a sparse 3D point cloud. These image-based methods paved the way for reconstructing larger exterior environments accurately and cheaply compared to laser scanners alone. Photogrammetry is now a widely used technique for cultural heritage documentation, architecture projects, and even film/game production.
Integral 3D Scanning Technologies
Today there are many 3D scanning technologies in use for different types of objects and environments. Structured light scanning projects patterns of lines or dots onto surfaces and reads distortions from a camera to calculate depth. It works well for industrial inspection, small objects and scanning interiors with controlled lighting. Laser scanning uses time-of-flight or phase-shift measurements to rapidly capture millions of precise 3D data points. Laser scanners excel at large outdoor environments like cultural heritage sites, construction projects and full building documentation. Multi-view stereo and photometric stereo algorithms fuse together image collections into full and detailed 3D reconstructions even with untextured surfaces.
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