Lab Snapshots

by Marek Ples


Photogrammetry as simple but effective 3D scanning method

Principle of technique

Fig.1 - 1) Real object; 2) Rotating object photographed from different angles; 3) Reconstructing a point cloud from set of pictures;
4) Point cloud converted to mesh.


Example

Using this method, we can create a 3D model of practically any physical object, in this case a small ammonite fossil from my collection (Fig.2).


Fig.2


Then the object is photographed while rotating around its axis at various angles (Fig.3).


Fig.3


In most cases, it can be stated that the more photographs taken (Fig.4), the more accurate the 3D reconstruction result will be.


Fig.4


For a relatively small object, typically 100-300 photos will be completely sufficient.


Then the COLMAP software (3.8-dev) was used to reconstruct a three-dimensional object from photographs (Fig.5). This way, we can achieve significant automation of the process, which can take a quite long time with a large number and high resolution of images.


Fig.5


After the program has made the necessary calculations, we obtain a cloud of points that represents the surface of the scanned object (Fig.6).


Fig.6


Further processing of the obtained data can be done using e.g. MeshLab. This way, we can clean the data of unnecessary elements (resulting from triangulation errors caused by imperfections of photos, the presence of light reflections, etc.), and then generate 3D mesh from point cloud (Fig.7). The created 3D object may require further minor processing: filling of holes, removal of artifacts, or adjustment of mesh resolution for a specific application.


Fig.7


The finished 3D object can be exported, for example, as a *.blend file and then rendered as 3D images (Fig. 8) or video sequence in Blender (Vid.1) or other 3D modeling software (special thanks to R. Bicki for rendering).


Fig.8


Vid.1


Note: If You want to print the finished model in 3D (FDM, SLS, SLA or other technique), it is best to export it to a *.stl file.



That's not all

For more information about these and other experiments or constructions, please visit www.weirdscience.eu. You can also contact me by email (moze.dzis@gmail.com).

Further readings: