Cloud feature detection

2:

• A method according to claim 1, wherein
• obtaining the image data comprises capturing, using one or more cameras, an image;
• and
• the method further comprises:
• measuring a time of day at which the camera captured the image;
• and
• determining the threshold luminance value (LT) using the measured time of day.

3:

• A method according to claim 1, wherein
• obtaining the image data comprises capturing, using one or more cameras, an image;
• and
• the method further comprises:
• measuring an orientation of the camera when the image was captured;
• and
• determining the threshold luminance value (LT) using the measured orientation.

6:

• A method according to claim 1, wherein the step of defining one or more intervals for the luminance values of the pixels comprises:
• determining a maximum of the luminance values of the pixels (Lmax);
• obtaining the threshold luminance value (LT), the threshold luminance value (LT) being less than the maximum of the luminance values (Lmax);
• and
• defining one or more intervals between the maximum of the luminance values (Lmax) and the threshold luminance value (LT).

8:

• A method according to claim 1, wherein
• the step of classifying comprises:
• for a first image segment classified as a cloud feature, assigning a first set of classification labels, the first image segment containing pixels having luminance values in a first interval;
• for a second image segment classified as a cloud feature, assigning a second set of classification labels, the second image segment containing pixels having luminance values in a second interval, the second interval being different to the first interval, the second set of classification labels being different to the first set of classification labels.

10:

• A method according to claim 1, the method further comprising, for an image segment classified as a cloud feature:
• determining a plurality of moments of that image segment;
• using the determined plurality of moments, determining a geometric representation of that image segment;
• and
• using the geometric representation of that image segment, determining a distance between the cloud feature represented by that image segment and an entity that obtained the image data.

11:

• A method according to claim 1, wherein:
• obtaining the image data comprises capturing, using one or more camera, an image;
• the camera is mounted on an aircraft;
• and
• the method further comprises, controlling the aircraft based on the detected cloud features.

12:

• Apparatus for detecting cloud features, the apparatus comprising:
• one or more sensors configured to obtain image data, the image data defining a plurality of pixels and, for each pixel, a respective luminance value;
• one or more processors configured to:
• define one or more intervals for the luminance values of the pixels;
• partition the image data into one or more image segments, each respective image segment containing pixels having a luminance value in a respective interval;
• and
• classify, as a cloud feature, each image segment containing pixels having luminance value greater than or equal to a threshold luminance value (LT).