Photogrammetry is a technology of making measurements from photographs for recovering surface points of objects and terrains. It is a technology as old as early photography and used since the 19th century.

In 3D technology photogrammetry is a powerful but easy instrument to acquire geometry and textures of many kinds of objects and environments without the need of expensive and sophisticated scanning hardware. In short, it is the poor man’s tool set to scan objects and terrains just with images rather than using laser scanners that cost a fortune.

Even though it uses only images to recover surface points, it is a complicated process that requires a software that takes care of all the calculations. The operator needs many technical skills to achieve the final result. The reward is a 3D mesh usable for any kind of 3D application, like games, virtual reality walkthroughs, documentation, rapid prototyping, replication of cultural heritage, 3D printing to name a few.

In this article I will introduce the major steps from choosing the object, through reconstruction the geometry up to the final application.The major steps are as follows:

• Preparations
• Image Acquisition
• Image Registration
• Point Cloud Reconstruction
• Mesh Reconstruction
• Mesh Optimization and Repair
• Texturing
• Export
• Publishing on a 3D Service

Considering the Object

For the sake of simplicity choose a simple flat object that has a certain kind of depth but no undercuts or extending parts. To learn the process and gently introduce possible issues it is important to start with an easy object like this rather than with the Neptun Fountain or the Statue of Liberty.

Make sure the object is clean. Any feature that doesn’t belong to the object will leave a mark in the resulting geometry and the generated texture. If allowed clean it with a soft brush or use a blower to remove dust. Sculptures in nature often contain lots of little disturbances that need to be removed to get a proper scan.