# US 2014/0192193 A1 · Method for acquiring images from arbitrary perspectives with uavs equipped with fixed imagers

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- Number: US 2014/0192193 A1
- Document ID: US20140192193A1
- Status: Published application
- Kind: A1
- Application number: 14/233,290
- Filed: 2012-06-21
- Published: 2014-07-10
- Earliest claimed: 2011-06-22
- Assignees: Sensefly S.A.
- Inventors: Jean-Christophe Zufferey; Antoine Beyeler
- Web page: https://patentgrep.com/patent/US20140192193A1

## CPC

- H04N 7/183: {for receiving images from a single remote source}
- G05D 1/0094: {involving pointing a payload, e.g. camera, weapon, sensor, towards a fixed or moving target}
- B64U 2101/30: for imaging, photography or videography
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR

## Abstract

A method for acquiring images of a photographic target from arbitrary perspectives with an unmanned aerial vehicle (UAV) equipped with at least one image acquisition device having a fixed acquisition direction with respect to the vehicle, said UAV having automatic navigation means allowing to reach an arbitrary location and automatic attitude control means allowing to transiently reach an arbitrary orientation in space, said photographic target being outside the current field of view of the acquisition device while the UAV flies along a predefined flying path, this method comprising: computing a target UAV position and an orientation in space required to acquire a desired image from a set of parameters, navigating to said target UAV position, modifying an attitude of the UAV in order to modify the acquisition direction to point toward the photographic target, acquiring images, and starting a recovery phase by controlling the UAV back to cruise attitude and navigate back along the predefined flying path.

## Claims

### Claim 1

A method for acquiring images of a photographic target from arbitrary perspectives with an unmanned aerial vehicle (UAV) equipped with at least one image acquisition device having a fixed acquisition direction with respect to the vehicle, said UAV having an automatic navigation system that allows the UAV to reach an arbitrary location and automatic attitude control system that allows the UAV to transiently reach an arbitrary orientation in space, said photographic target being outside the current field of view of the acquisition device while the UAV flies along a predefined flying path, the method comprising the steps of:
computing a target UAV position and an orientation in space required to acquire a desired slanted image from a set of parameters pertaining to the desired photographic target, a desired perspective and a relative orientation of the image acquisition device with respect to the UAV;
navigating, using the automatic navigation system, to said target UAV position;
modifying an attitude, which comprises at least one of a pitch, roll or yaw angle, of the UAV in order to modify the acquisition direction to point toward the photographic target;
acquiring images when the acquisition direction points toward the photographic target with the desired perspective; and
starting a recovery phase by controlling the UAV back to the predefined flying path.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising the steps of:
determining an anticipatory location placed on a line upstream between the target position and the photographic target, at a distance determined by the flight dynamics of the UAV; and
flying first to said anticipatory location before heading to the target UAV position.

### Claim 3 (depends on 2)

The method according to claim 2, further comprising the step of determining the direction and the amplitude of the wind and shifting the anticipatory location laterally such as to compensate for the lateral drift of the wind.

### Claim 4 (depends on 2)

The method according to claim 2, further comprising the steps of:
calculating an altitude resulting from modifying the attitude; and
shifting the anticipatory location vertically to compensate for the altitude.

### Claim 5 (depends on 1)

The method according to claim 1, wherein it comprises the steps of:
deploying a retractable objective of the image acquisition device while the UAV is in the air or when the UAV reaches the target position; and
retracting the retractable objective after the image acquisition device has finished acquiring the images or before landing.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the image acquisition device comprises an objective with zoom capabilities, the method further comprising the step of:
taking into account the zoom factor to determine the target position.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the UAV comprises a plurality of image acquisition devices arranged on its airframe, each acquiring device taking images in sequence.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the UAV is powered by a propulsion motor during the navigation, the method further comprising the step of reducing the speed or stopping said motor when acquiring the images.

### Claim 9 (depends on 1)

The method according to claim 1, in which the computing of the target UAV position comprises the steps of:
determining, on a map display, a ground coverage trapeze defining a desired image and perspective by means of virtual handles allowing to change the trapeze position, shape and orientation; and
calculating the target position and orientation of the UAV by taking into account the field of view of the acquisition device.

### Claim 10 (depends on 1)

The method according to claim 1, in which a series of images are acquired in order to systematically cover a photographic target from various bearings or elevations, thus defining a series of set of parameters calculated according to the steps of:
determining on a map display a photographic target and a width of ground coverage, by means of virtual handles operable to change a width position and shape;
defining a bearing or elevation resolution determining an angle increment between the successive bearings or elevations; and
calculating each set of parameters by successively changing the bearing or elevation according to a bearing or elevation resolution thus determining the set of successive target positions and orientations of the UAV.

### Claim 11

An unmanned aerial vehicle (UAV) comprising:
at least one image acquisition device having a fixed acquisition direction with respect to the vehicle;
an automatic navigation system operable to control the pitch, roll and the yaw of the UAV in order to fly along a predefined flying path until a photographic target being outside the current field of view of the image acquisition device while the UAV flies along said predefined flying path;
means for interrupting the automatic navigation means in the vicinity of the photographic target;
means for temporarily modifying at least one of the pitch, roll or yaw in order to modify the acquisition direction to point toward the photographic target and to acquire images with the image acquisition device; and
means for restarting the navigation means for moving the UAV back to the predefined flying path.

### Claim 12 (depends on 11)

The UAV according to claim 11, wherein the automatic navigation system comprises an inertial measurement unit and/or a GPS and/or a magnetometer and/or visual sensors configured to estimate an orientation and a position of said UAV.

### Claim 13 (depends on 11)

The UAV according to claim 11, wherein the image acquisition device comprises a retractable objective configured to deploy before acquisition of images, and to retract when image acquisition is terminated.

### Claim 14 (depends on 11)

The UAV according to claim 11, further comprising a plurality of image acquisition devices arranged on a fuselage of the UAV, each image acquisition device operable to take images of a series of photographic targets.

### Claim 15 (depends on 14)

The UAV according to claim 14, wherein the image acquisition devices are configured to take three dimensional images of the photographic target.