Localization and mapping by a group of mobile communications devices

1 . A mobile communications device for performing localization and mapping, the mobile communications device comprising:

at least one visual sensor operative to capture visual sensor data of a local environment of the mobile communications device, and

processing circuitry causing the mobile communications device to be operative to:

derive key-point descriptors from the visual sensor data, the derived key-point descriptors representing visual features of the local environment;

derive concealed representations of the derived key-point descriptors, by applying a current permutation to each derived key-point descriptor;

determine a pose of the mobile communications device relative to a point-cloud map representing the local environment, wherein the point-cloud map representing the local environment is a concealed representation of a point-cloud map;

map the derived key-point descriptors onto the point-cloud map, thereby associating each derived key-point descriptor with a position in the point-cloud map, by

matching the concealed representations of the derived key-point descriptors with concealed representations of key-point descriptors comprised in the concealed representation of the point-cloud map, the key-point descriptors comprised in the concealed representation of the point-cloud map representing visual features of the local environment, and

associating the derived key-point descriptors with positions of concealed representations of key-point descriptors comprised in the concealed representation of the point-cloud map which match the concealed representations of the derived key-point descriptors; and

transmit the concealed representations of the derived key-point descriptors, together with associated positions of the derived key-point descriptors in the point-cloud map, to a map server,

wherein the current permutation is a shared secret or is derivable from a shared secret, which shared secret is available to a group of mobile communications devices comprising the mobile communications device.

2 . The mobile communications device according to claim 1 , further operative to:

acquire the concealed representation of the point-cloud map from the map server, and

reconstruct the key-point descriptors representing visual features of the local environment from the concealed representations of the key-point descriptors comprised in the concealed representation of the point-cloud map, by applying an inverse of the current permutation to the concealed representations of the key-point descriptors comprised in the concealed representation of the point-cloud map.

3 . The mobile communications device according to claim 1 , operative to derive key-point descriptors from the visual sensor data by:

extracting key points from the visual sensor data, and

deriving the key-point descriptors from the extracted key points.

4 . The mobile communications device according to claim 1 , wherein the current permutation is a combined permutation of a sequence of incremental permutations, and the shared secret is a subsequent incremental permutation, the mobile communications device further operative to derive a subsequent permutation by applying the subsequent incremental permutation to the current permutation.

5 . The mobile communications device according to claim 1 , further operative to:

receive current concealed representations of key-point descriptors from the map server,

derive subsequent concealed representations of the key-point descriptors from the received current concealed representations of the key-point descriptors, which subsequent concealed representations are different from the received current concealed representations, and

transmit the subsequent concealed representations of the key-point descriptors to the map server.

6 . The mobile communications device according to claim 5 , operative to derive the subsequent concealed representations of the key-point descriptors by applying a subsequent incremental permutation to the received current concealed representations of the key-point descriptors.

7 . The mobile communications device according to claim 1 , wherein the concealed representations of the derived key-point descriptors are transmitted to the map server for merging of the concealed representations of the derived key-point descriptors with another concealed representation of the point-cloud map comprising concealed representations of key-point descriptors, which concealed representations of key-point descriptors comprised in the another concealed representation of the point-cloud map have been concealed using the same current permutation as the transmitted concealed representations of the derived key-point descriptors.

8 . The mobile communications device according to claim 1 , wherein the at least one visual sensor comprises one or more of a monocular camera and an RGB camera, and the visual sensor data comprises one or more digital images.

9 . The mobile communications device according to claim 1 , being any one of: a smartphone, a mobile phone, a tablet, a laptop, a smartwatch, a head-mounted display device, an Augmented-Reality device, a Mixed-Reality device, an autonomous vehicle, and a drone.

10 . A method for performing localization and mapping, the method being performed by a mobile communications device and comprising:

capturing visual sensor data of a local environment of the mobile communications device, using at least one visual sensor comprised in the mobile communications device;

deriving key-point descriptors from the visual sensor data, the derived key-point descriptors representing visual features of the local environment;

deriving concealed representations of the derived key-point descriptors, by applying a current permutation to each derived key-point descriptor;

determining a pose of the mobile communications device relative to a point-cloud map representing the local environment, wherein the point-cloud map representing the local environment is a concealed representation of a point-cloud map;

mapping the derived key-point descriptors onto the point-cloud map, thereby associating each derived key-point descriptor with a position in the point-cloud map, by

matching the concealed representations of the derived key-point descriptors with concealed representations of key-point descriptors comprised in the concealed representation of the point-cloud map, the key-point descriptors comprised in the concealed representation of the point-cloud map representing visual features of the local environment, and

associating the derived key-point descriptors with positions of concealed representations of key-point descriptors comprised in the concealed representation of the point-cloud map which match the concealed representations of the derived key-point descriptors; and

transmitting the concealed representations of the derived key-point descriptors, together with associated positions of the derived key-point descriptors in the point-cloud map, to a map server,

wherein the current permutation is a shared secret or is derivable from a shared secret, which shared secret is available to a group of mobile communications devices comprising the mobile communications device.

11 . The method according to claim 10 , further comprising:

acquiring the concealed representation of the point-cloud map from the map server, and

reconstructing the key-point descriptors representing visual features of the local environment from the concealed representations of the key-point descriptors comprised in the concealed representation of the point-cloud map, by applying an inverse of the current permutation to the concealed representations of the key-point descriptors comprised in the concealed representation of the point-cloud map.

12 . The method according to claim 10 , wherein deriving key-point descriptors from the visual sensor data comprises:

extracting key points from the visual sensor data, and

deriving the key-point descriptors from the extracted key points.

13 . The method according to claim 10 , wherein the current permutation is a combined permutation of a sequence of incremental permutations, and the shared secret is a subsequent incremental permutation, the method further comprising:

deriving a subsequent permutation by applying the subsequent incremental permutation to the current permutation.

14 . The method according to claim 10 , further comprising:

receiving current concealed representations of key-point descriptors from the map server,

deriving subsequent concealed representations of the key-point descriptors from the received current concealed representations of the key-point descriptors, which subsequent concealed representations are different from the received current concealed representations, and

transmitting the subsequent concealed representations of the key-point descriptors to the map server.

15 . The method according to claim 14 , further comprising:

deriving the subsequent concealed representations of the key-point descriptors by applying a subsequent incremental permutation to the received current concealed representations of the key-point descriptors.

16 . The method according to claim 10 , wherein the concealed representations of the derived key-point descriptors are transmitted to the map server for merging of the concealed representations of the derived key-point descriptors with another concealed representation of the point-cloud map comprising concealed representations of key-point descriptors, which concealed representations of key-point descriptors comprised in the another concealed representation of the point-cloud map have been concealed using the same current permutation as the transmitted concealed representations of the derived key-point descriptors.

17 . The method according to claim 10 , wherein the at least one visual sensor comprises one or more of a monocular camera and an RGB camera, and the visual sensor data comprises one or more digital images.

18 . The method according to claim 10 , wherein the mobile communications device comprises one of: a smartphone, a mobile phone, a tablet, a laptop, a smartwatch, a head-mounted display device, an Augmented-Reality device, a Mixed-Reality device, an autonomous vehicle, and a drone.