Considerations for Conducting Separate IR and RGB Flights

It is possible to capture IR and RGB data in separate flights using different drones/sensors rather than using a single drone with a dual (IR/RGB) camera. Raptor Maps requires RGB and IR imagery (inspection level and obliques) to be captured on the same day. If a solar site is too large to capture in a single day, the pilot can break the site up into sections, ensuring that RGB and thermal imagery (including obliques) are captured on the same day for each section.

Altitude will need to be adjusted for each flight to capture the required Ground Sample Distance (GSD) given the specific sensor and inspection level of the flight. GSD requirements for thermal and RGB imagery for each inspection level are listed below. Thermal (IR) imagery must be RJPEG (the Zenmuse XT has an option for RJPEG and JPEG - ensure RJPEG is selected). RGB imagery must be JPEG. All imagery must contain metadata (GPS, relative altitude, gimbal altitude, and timestamp).

Thermal Imagery

Type of Inspection Raptor Overview Raptor Standard Raptor Comprehensive
Description Ideal for rapid drone flights and string-level outages Ideal for annual preventative maintenance Meets IEC TS 62446-3 thermography standards for Absolute Temperature Accuracy
Smallest visible features Module Diode, Hot Spot, and Cell Diode, Hot Spot, and Cell
Ground sample distance 15.0 ± 5.0 cm/pixel 5.5 ± 0.5 cm/pixel 3.0 ± 0.5 cm/pixel
Maximum speed 30 mph 12 mph 7 mph

Supported Drones and Thermal (IR) Sensors

Make

Model

Sensor

DJI

M200

XT

DJI

M210

XT

DJI

M210 RTK

XT

DJI

M200 V2

XT

DJI

M600

XT

DJI

Inspire 1

XT

M210 Compatibility

If using the DJI M210 (or M210 RTK) dual gimbal with separate IR/RGB sensors, DJI Ground Station Pro will only capture imagery from slot 1. GS Pro will not simultaneously capture imagery from sensors in slot 1 and 2. The pilot will have to conduct separate IR/RGB flights and ensure the sensor is mounted in slot 1 for each flight. The following image shows where slot 1 and slot 2 are labeled on the M210 dual gimbal mount.

Visible (RGB) Imagery

Type of Inspection Raptor Overview Raptor Standard Raptor Comprehensive
Description Ideal for rapid drone flights and string-level outages Ideal for annual preventative maintenance Ideal for warranty and commissioning
Smallest visible features Module Cell Sub-cell
Ground sample distance 5 ± 1.0 cm/pixel 2.0 ± 1.0 cm/pixel 1.0 ± 0.5 cm/pixel

Supported Drones and RGB cameras

Make

Model

Camera

DJI

Phantom 4

Built-In

DJI

Phantom 4 Pro

Built-In

DJI

Phantom 4 Pro V2

Built-In

DJI

Phantom 4 RTK

Built-In

DJI

Inspire 1

Zenmuse X3, Zenmuse X5

DJI

Inspire 2

Zenmuse X4S, Zenmuse X5S with 15mm DJI lens.

DJI

M200

Zenmuse X4S, Zenmuse X5S with 15mm DJI lens.

DJI

M210 RTK

Zenmuse X4S, Zenmuse X5S with 15mm DJI lens.

DJI

M200 V2

Zenmuse X4S, Zenmuse X5S with 15mm DJI lens.

DJI

M200 RTK V2

Zenmuse X4S, Zenmuse X5S with 15mm DJI lens.

DJI

M300

P1

DJI

Mavic

Built-In

DJI

Mavic 2 Pro

Built-In

DJI

Mavic 2 Enterprise

Built-In

DJI

Air 2S

Built-In

Parrot

ANAFI

Built-In

Parrot

ANAFI USA

Built-In

Autel

Evo II

Built-In

Autel

Evo II Pro

Built-In

Autel

Evo II RTK

Built-In

Skydio

X2

Built-In

Calculating GSD or Flight Altitude from GSD

To calculate GSD or calculate altitude to obtain a certain GSD, you will need to know the following variables:

Sensor height (millimeters)
Sensor width (millimeters)
Image height (pixels)
Image width (pixels)
Focal length of the sensor (millimeters)
Flight altitude (centimeters) - if calculating GSD
GSD (cm/pixel) If calculating altitude for a given GSD

GSD Equations:

GSDh = flight altitude x sensor height / focal length x image height
GSDw = flight altitude x sensor width / focal length x image width

Whichever value is larger (GSD height or width) will be the functional GSD to account for the "worse" resolution of the two.

GSD Calculators

There are several open-source GSD calculators which allow you to select from a preset list of drones/payloads or manually enter the variables necessary to calculate GSD. Here is a non-exhaustive list of GSD Calculators:

Propeller
Handal Selaras
Pix4D (Downloadable .xlsx/.ods format)