Louisiana Helicam writes monthly publication articles regarding drone/UAV/UAS usage in the pulp and paper industry.  The January 2017 article is contained below:

We’ve witnessed the introduction of many new photogrammetric applications over the past few years.  Photogrammetry is most often referred to as the science of making measurements from photographs.  I typically describe it as the combining of multiple 2D images to make one 3D model. 

Louisiana Helicam tested a number of standalone and cloud-based photogrammetry applications but eventually chose Pix4Dmapper Pro for the following reasons:

• A laptop can process much of the data on the trip home
• Point cloud manipulation (chip pile conveyor removal, site cleanup, etc.)
• Simple Ground Control Point (GCP) implementation

I typically use Pix4Dmapper Pro for stockpile volume calculation (paper mills) and localized topo maps (hunting leases).  However, other uses include:

• Up to date site maps (more current than Google Earth)
• Digital Surface Models (DSM)
• Digital Terrain Models (DTM)
• Cut and fill measurements for earthmoving projects
• NDVI (crop stress) studies for agriculture
• Structure modeling for both CAD and 3D printing applications
• Benchmark model data for structural stress/sag over time

The Pix4D process requires multiple images with sufficient overlap regardless of the intended output.  For example, one of the stockpiles that I map on a monthly basis is 19.4 acres.  It takes an average of 240 to 250 orthogonal images at 80% overlap to create the 3D model to be used for volumetric calculation.  Sufficient overlap is mandatory for creating a 3D model with enough information for an accurate volume survey.  That said, Normalized Difference Vegetative Index (NDVI) studies require less overlap if crop height measurements are not needed. 

Stay tuned for next month’s article.  It will contain more information regarding the image collection process and the Pix4D data workflow.