When flying a drone, it takes multiple images of each point on the ground during the mission. This raw image data is then stitched together to create a 3D model of the site. More images of any given point on the ground mean better accuracy when it comes to creating the model. A lack of images of the middle of a site can result in holes, while on the outside one will tend to see jagged edges and floating objects.

Open

Causes and Solutions

Mission Planning

The most common cause for blank spots in the mission area is imaging height that was set too low to include all of the terrains in the mission area.  For example, an image capture height of 30 feet on a site with hills, buildings, or stockpiles taller than 30 feet over the takeoff location will cause holes to appear in the mission area.

As you plan your mission, keep in mind the topography of the area you are intending to fly. Whether there is a pit or a pile in the path of the drone, it will stay consistent at the altitude specified in your mission planning. If you are flying a rising terrain, make sure to not only set your fly height with an appropriate buffer but make sure to also set your imaging height to include the higher points of the site for them to be included in the model.

While mission planning keep an eye on your data size as well. If your data size is too low (below 250 MB)) there will likely be stitching issues since the drone will not have taken enough images for there to be a proper amount of photo overlap to render a 3D model.

 Unmappable Terrain

The raw images taken by the drone are turned into a detailed 3D model by finding shared points in multiple images by a process called photogrammetry.  Certain types of terrain, such as those with large homogenous areas, can make it difficult or impossible to do this accurately.  By following the tips listed below you can maximize your success with terrain that may be challenging for the photogrammetry to find matching points:

• Fresh snow.  To capture snow, we recommend waiting several days after a fresh snowfall, otherwise driving or creating texture on the surface of the snow.

• Fine sand, especially frac sand.  To capture ultra-fine sand, we recommend flying at a lower altitude than normal on a bright day around noon.

• Still water.  Water is very difficult to capture and stitch, so we highly recommend avoiding including it in your mission plan as we cannot guarantee this terrain will stitch. 

• Fields and other short vegetation. To successfully fly large uninterrupted fields with consistent low vegetation, we recommend flying at a lower altitude than normal and during mid-day on a bright day.

Terrain that moves during the mission is generally difficult to create an accurate 3D model and is generally not mappable using the Kespry system.  Movement of trees, water, or other terrains generally prevents any photogrammetry-based solution from accurately mapping these areas however you can still use the Inspect workspace in the Kespry Cloud to view and annotate individual missions.  Examples of terrain that will generally not map using the Kespry system include:

• Dense trees or forest

• Tall grass or other crops, especially on windy days

• Water