What Is Photogrammetry? Exploring SHINING 3D’s Video Photogrammetry (VPG)

While traditional photogrammetry has long been used to improve measurement accuracy for large-scale metrology, recent advances have introduced Video Photogrammetry (VPG), which streamlines the workflow by replacing hundreds of static images with continuous video capture. This article explains how VPG works, how it differs from conventional photogrammetry, and why it is becoming an important technology in industrial 3D measurement.

What Is Photogrammetry

Introduction to Photogrammetry

Photogrammetry is a technology that uses a camera or combination of cameras to measure the shape, size, and spatial position of a subject. In short, this technique uses photography as a tool and measurement as a purpose to extract information from a 2D image and construct a 3D model.

Photogrammetry

Why Photogrammetry Is Applied in the 3D Scanning Industry

3D scanning integrates optics, mechanics, electronics, and algorithms to measure and capture the spatial structure, dimensions, and color textures of objects, creating accurate digital 3D models. This technology converts physical objects into detailed point clouds and color data that computers can process. The process involves stitching together data from markers, features, or textures, which can introduce errors. These errors tend to accumulate, particularly when scanning large objects ranging from several meters to tens of meters in size.

To minimize the cumulative error, photogrammetry technology is introduced to high-accuracy 3D scanning. A high-accuracy handheld 3D scanner can be used to efficiently obtain dense point cloud information of the measured parts with markers; while photogrammetry equipment shoots scale bars arranged around the parts and the markers on the surface of the parts at multiple angles to form high-accuracy markers and coded targets framework in the software. The combination of the two data can control the global accuracy of 3D scanning of large-size objects.

coded targets on scale bars and marker (global markers)

Traditional Independent Industrial Photogrammetry System

In traditional industrial photogrammetry, coded targets and markers are placed on and around the object’s surface. High-resolution cameras capture the object from various angles and positions, producing a series of photos. These photos are then imported into software that automatically calculates the spatial positions of the coded targets and markers. The resulting data files can be imported into 3D data acquisition software, providing complete 3D data.

Traditional independent industrial photogrammetry system

Disadvantages

• Multiple angles and photo requirements: Requires users to stand at multiple angles around large parts and take numerous photos from fixed points.
• High learning curve: Requires operators to have extensive experience to ensure stable accuracy.
• Complex coded targets setup: Traditional photogrammetry systems require coding points to determine three-dimensional spatial relationships. The process of arranging coding points is complex, and larger objects require more coding points, which is time-consuming.

Traditional independent industrial photogrammetry

How to Use Video Photogrammetry (VPG)

To capture accurate mesh data with a handheld 3D scanner, first take multi-angle shots of well-calibrated scale bars positioned around the object. The scan software will detect markers and coded targets on the scale bars, using them to ensure overall accuracy when scanning large objects.

Take FreeScan UE Pro2 as an example, which has an integrated video photogrammetry (VPG) function. Without the use of coded points, accurate measurement results can be efficiently obtained in the photogrammetry mode, with a volume accuracy of 0.02 + 0.015 mm/m. The video below demonstrates the complete workflow.

For larger components, the benefits of VPG become even more evident. Using FreeScan Trak Nova, a 40-meter wind turbine blade can be measured with a volumetric accuracy of 0.046 + 0.012 mm/m. By replacing traditional coded-target photogrammetry with VPG, the workflow becomes faster and more efficient while maintaining the accuracy required for large-scale industrial inspection. 

Beyond large-scale applications, VPG is also implemented in standalone FreeScan Omni for high-precision industrial inspection. In the example below, a turbofan engine is scanned using VPG, achieving a volumetric accuracy of 0.02 + 0.015 mm/m, making it suitable for civil aviation-grade measurement tasks where both accuracy and efficiency are critical.

Advantages of Innovative Video Photogrammetry (VPG)

• Global accuracy control: The 3D scanning equipment features an integrated design with a built-in video photogrammetry function, making it versatile and adaptable to various object shapes. It efficiently controls the global accuracy of 3D data for large workpieces.
• Efficient, stable and easy to use: Utilizing continuous full-angle shooting, there’s no need for fixed-point shooting at specific angles. The measurement process is straightforward, allowing even novices to capture all angles and maintain stable accuracy.
• Real-time data display: Results are shown through real-time video streaming, providing high visibility. Missing angles can be quickly supplemented to ensure overall dimensional accuracy.
• Convenient and flexible operation: With strong environmental adaptability, the equipment can perform video photogrammetry (VPG) on super-large and heavy workpieces without needing to move to an open area.

Conclusion

SHINING 3D’s high-accuracy 3D scanning technology, combined with built-in video photogrammetry (VPG), delivers an accurate and efficient optical measurement solution deeply embedded in the industrial manufacturing sector. This advanced technology, featured in models like FreeScan Trak ProW, FreeScan Trak Nova, FreeScan Omni, FreeScan Trio, FreeScan UE Pro2, supports every stage of production. It helps companies accelerate product development, enhance production efficiency, and improve product quality, leading to more refined manufacturing processes.