Photogrammetry Underground

Does it make sense to use photogrammetry underground?     

Photogrammetry (using measurements taken from photographs to plot the exact location of features and items) is often used in land-scale surveying and civil engineering environments. But does it make sense to use photogrammetry underground, e.g. within an underground mine?

The basic methodology behind photogrammetry is to use overlapping 2D photographs of the same area or object that are shot from two or more different angles to construct a 3D model that contains depth information (think of two cameras seeing the same scene in a similar way as your eyes seeing slightly different information in a 3D movie, giving the illusion of depth). Essentially, photogrammetry uses visual information in the form of photographs to construct a virtual 3D image.

By comparison, LiDAR (light detection and ranging) laser-based scanning systems use pulses of light energy (laser beams) to map out an area in 3D. As these pulses bounce off of objects, they create a vast amount of data points for the scanner to record.

Despite its popularity in surface applications, using photogrammetry underground is subject to certain limitations, including:

  • Insufficient light. Like all photographic equipment, the cameras used in photogrammetry require good lighting to produce quality results. Lighting in most underground mines that may be adequate for operational needs is not usually suitable for photography. The means that the use of photogrammetry underground is dependent on bringing in a lot of specialized lighting equipment.
  • Inaccessibility. In all underground mines, there are certain areas that are cramped, dangerous to enter, or inaccessible for whatever reason. Without being able to get cameras into these areas, it’s hard to build a comprehensive 3D model using photogrammetry.
  • Processing time and resources. Processing 2D photographic material to extract the many data points required to form an accurate 3D model can be very time-consuming and usually requires significant computing power.

Mobile 3D LiDAR scanners like the uGPS Rapid Mapper™ can operate in very low light (or even no light) conditions, scan inaccessible areas with laser beams, and instantly produce 3D point cloud data within the device, in a format that can be transferred and used on any standard PC or laptop (and even many mobile devices).

One of the reasons some mine managers have opted to use photogrammetry underground rather than laser scanners is that certain LiDAR laser scanners previously used in underground mines and other similar applications gained a reputation for being expensive and difficult to operate, requiring extensive staff training.

The uGPS Rapid Mapper™, though, does not have these problems. This rugged, reliable, low-maintenance unit offers all the benefits of laser scanning at an affordable price and is so easy to operate that existing mine personnel can begin using it with only minimal instruction. 

Contact us now to get more information about the benefits of using LiDAR-based uGPS Rapid Mapper™ scanners in your underground mine.