What are the flight modes available in Site Scan Flight for ArcGIS?

Answer

Site Scan Flight for ArcGIS offers different flight modes, as well as the ability to plan flights ahead of time. The flight modes include:

• Area Survey
• Crosshatch Survey
• Perimeter Scan
• Inspection
• Vertical
• Panorama

All flight modes deliver the same output formats, which are:

• orthomosaics (*.tiff) 
• digital elevation model/DEM (*.tiff)
• digital terrain model/DTM (*.tiff)
• contours (*shp.zip)
• point clouds (*.rcs, *.las.zip)
• 3D mesh (*.rcm, *.obj)

Area Survey

• The quickest way to map a given area.
• The drone is typically flown 'nadir', with the camera pointed straight down, that is, 0º camera angle.
• Ideal for mapping large areas with little elevation change (relative to the flight altitude) or few vertical features, for example, buildings.

Note:
Area Survey is used if elevation changes or vertical features are less than one-fourth of the flight altitude.
• For a flight at 200 ft (61 m), elevation change must be less than 50 ft (15 m)
• For a flight at 400 ft (122 m), elevation change must be less than 100 ft (30 m)

Below is an image of an orthomosaic using Area Survey.

Below is an image of a orthomosaic using Area Survey with a 5-foot contour overlay.

Crosshatch Survey

• Ideal for sites with many vertical features, for example, buildings or elevation changes.
• Requires about twice the flight time for a given area as compared to Area Survey.
• Must be flown with the camera set at an angle; a camera angle set between 35 and 40 degrees delivers the best results in most cases.
• Must be flown at least 100 ft (31 m) above the tallest obstacle.
• Photos can be merged with photos from an Area Survey for processing.

Note: 
Relatively level sites are not ideal for Crosshatch Survey, even if it has features such as stockpiles, cars, or trenches. In these cases, Area Survey with the camera set at a small angle is recommended.

Below is a merged Area Survey and Crosshatch Survey image.

Perimeter Scan

• Ideal for creating high-resolution 3D models of tall individual structures.
• Photos can be merged with photos from an Area Survey for processing.

For best results:

• Offset; the larger the building, the farther away from it must the drone fly. Note that offset directly affects the resolution and number of photos taken. 100-foot (30 m) offset works well for small to medium-sized buildings such as residential towers. Fly far enough from the building so a corner of the building is visible in the majority of the photos.
• It is recommended to set the minimum altitude slightly higher than the top of the structure scanned, for safety reasons.
• Fly the drone manually over the structure; to determine the height of the building.
• Set the maximum altitude at 1.5x to 2x higher than the minimum altitude.
• Set gimbal angles of approximately 35 degrees at minimum altitude and 65 degrees at maximum altitude; using the settings recommended above.

Below is an image of a tower with a height of 331 ft. The offset is 70 ft, reduced from the above recommendation, due to obstacles. The minimum altitude is set at 345 ft, and the maximum altitude at 400 ft.

Inspection

• Ideal for inspecting structures and job sites.

Vertical

• Ideal for mapping vertical structures such as buildings, dams or mining excavations.
• Uses 3D flight planning to better understand the relative position of the drone compared to the structure to map.
• Uses three vertices to plan out the flight, to correctly map vertical structures that have an angle.

Panorama

• Allows taking a 360-degree or panorama photo of the job site.
  Refer to How To: Fly a Panorama flight with Site Scan Flight for ArcGIS for more information.