Capturing Solar Site Oblique Imagery

 

 

Oblique images provide another means to identify anomalies, and are especially helpful in identifying larger scale issues, such as those associated with inverters and combiners.

Important note: Obliques must be captured the same day as inspection level imagery.

Review these requirements before an inspection to ensure the images you capture meet Raptor Maps standards.

Note that each image should provide an overview of 2 MWdc.

Element

Coverage
Lens
Images
Image Resolution
Maximum Speed
Altitude
Environmental Conditions

Requirement

Each image should provide an overview of 2 MWdc

The 2 megawatts should appear in the lower half of the field of view of the image, see example, below

13 mm or 19 mm; see specifics for each lens below
IR (radiometric JPEG) and RGB (JPEG)
640 x 512 pixels or greater
15 mph / 24 kph
400 ft / 122 meters above ground level

Skies clear and sunny or slightly overcast

Irradiance greater or equal to 600 Watts per square meter

Humidity ideally less than 60%

Flight Path

The flight path specifics will vary depending on your lens length.

Element

Gimbal Pitch
Overlap
Flight Path

13 mm Lens

70 degrees from nadir (20 degrees down from the horizon)
80% front overlap (direction of flight) and 20% side overlap

Begin flight path at a distance of 480 feet / 146 meters from the first row of panels

Each subsequent side pass should begin 660 feet / 200 meters from the end of the previous (see illustration, below)

19 mm Lens

74 degrees from nadir (16 degrees down from the horizon)
80% front overlap (direction of flight) and 27% side overlap

Begin flight path at a distance of 762 feet / 232 meters from the first row of panels

Each subsequent side pass should begin 660 feet / 200 meters from the end of the previous (see illustration, below)

Here is a sample of an oblique image of 2 megawatts: the 2 megawatts should appear in the lower half of the field of view of the image.

Planning for Oblique Flights

Many pilots fly manually to collect oblique imagery.

If, however, you would like to create an automated flight plan, you will need to use a workaround. Here is how to do so with the DJI Ground Station Pro (GSP).

The workaround requires creating a custom camera setting for oblique imagery.

Important note: Use this custom camera setting for oblique imagery only. Don’t forget to switch out of this mode when undertaking other portions of the inspection!

Use these settings to create a simulated camera with a 4 mm focal:

Once you’ve created this custom camera, create a flight plan with these settings:

Element

Altitude
Shooting Angle
Front Overlap Ratio
Side Overlap Ratio

Setting

400 feet above ground level
Perpendicular to main path
80%
If using 13 mm lens: 20% If using 19 mm lens: 27%

IAdditional Instructions for 13 mm Lenses

Move the polygon from your normal inspection imagery back by about 480 feet from the solar farm. This will ensure that the first pass of images captures the beginning row of the farm. When you are ready to start, use your RC controller to manually set your gimbal to 70 degrees from nadir and you should be good to go.

Additional instructions for 19 mm Lenses

Move the polygon from your normal inspection imagery back by about 762 feet from the solar farm. This will ensure that the first pass of images captures the beginning row of the farm. When you are ready to start, user your RC controller to manually set your gimbal to 74 degrees from nadir with your RC controller and you should be good to go.

Important note: Make sure to change your camera settings back to proceed with the capture of normal thermal inspection imagery.