EP-4584948-B1 - METHOD FOR TRANSMITTING TYPE OBJECT DETECTION DATA, METHOD FOR PROCESSING AN ELECTRONIC DEVICE RECEIVING DETECTION DATA TRANSMITTED BY A PLURALITY OF ACQUISITION DEVICES; ASSOCIATED TRANSMITTER AND RECEIVER DEVICES

EP4584948B1EP 4584948 B1EP4584948 B1EP 4584948B1EP-4584948-B1

Inventors

PESQUET-POPESCU, Béatrice
THEBAULT, DIDIER

Dates

Publication Date: 20260506
Application Date: 20230907

Claims (10)

Method for transmitting type object detection data implemented by a transmitter device (4_1) intended for a receiver (2) via at least one wireless transmission link (3), the transmitter device (4_1) comprising an image capture unit (40_1) and a detection unit (43_1) detecting if type objects defined in a predefined list (L1) are present in an image captured by the capture unit (40_1) and according to which detection probability, said method comprising, after the detection process has been carried out on a captured image, the following steps implemented by the transmitter device (4_1): - if a detection probability greater than a predetermined threshold S for a type object has been determined for the considered image, and if the current state of the transmission link does not verify predefined threshold transmission conditions, then the transmitter device (4_1) applies the following rules to determine the content to transmit relative to the image: - not transmitting a portion of the image comprising said detected type object is not carried out; - transmitting data indicating at least one of an identifier of the detected type object, the detection probability of said object and a geographical position; - if, for the considered image, a detection probability greater than said predetermined threshold S has not been determined, but if a detection probability of between said threshold S and another predetermined threshold S' strictly less than S and strictly positive has been determined, then the transmitter device (4_1) applies the following rules to determine the content to transmit relative to the image: - transmitting at least one portion of the image comprising said detected type object associated with data indicating at least one of an identifier of the detected type object, the detection probability of said object and a geographical position, and whereby, before transmission, an image compression is selectively applied to said image portion as a function of the current state of the transmission link, including for transmission link states not verifying said predefined threshold transmission conditions; the image portion being, following said compression, transmitted in compressed form.
Data transmission method according to claim 1, whereby the compression mode being selected between several compression modes as a function of said transmission link current state.
Data transmission method according to claim 1 or 2, whereby if a detection probability greater than the predetermined threshold S for at least one type object has been determined for the considered image, and if the current state of the transmission link verifies said predefined threshold transmission conditions, then, the transmitter device (4_1) applies the following rules to determine the content to transmit relative to the image: - transmitting at least one portion of the image comprising said detected type object associated with data indicating at least one of an identifier of the detected type object, the detection probability of said object and a geographical position.
Transmitter device (4_1), said device being adapted to transmit type object detection data intended for a receiver (2) via at least one wireless transmission link (3), and comprising an image capture unit (40_1) and a detection unit (43_1) adapted to detect if type objects defined in a predefined list (L1) are present in an image captured by the capture unit and according to which detection probability, said transmitter device (4_1) being adapted to, after the detection process has been carried out by the detection unit on a captured image by the capture unit, if a detection probability greater than a predetermined threshold S for a type object has been determined for the considered image, and if the current state of the transmission link does not verify predefined threshold transmission conditions, apply the following rules to determine the content to transmit relative to the image: - not transmitting a portion of the image comprising said detected type object is not carried out; - transmitting data indicating at least one of an identifier of the detected type object, the detection probability of said object and a geographical position; said transmitter device (4_1) being adapted to, after the detection process has been carried out by the detection unit on an image captured by the capture unit, if, for the considered image, a detection probability greater than said predetermined threshold S has not been determined, but if a detection probability of between said threshold S and another predetermined threshold S' strictly less than S and strictly positive has been determined, apply the following rules to determine the content to transmit relative to the image: - transmitting at least one portion of the image comprising said detected type object associated with data indicating at least one of an identifier of the detected type object, the detection probability of said object and a geographical position, and before transmission, applying an image compression selectively to said image portion as a function of the current state of the transmission link, including for transmission link states not verifying said predefined threshold transmission conditions; the image portion being, following said compression, transmitted in compressed form.
Processing method implemented in a receiver electronic device (2) receiving, via wireless transmission links, detection data coming from a plurality of acquisition devices (1) capturing images, and detecting if type objects defined in a predefined list are present in a captured image, the receiver device comprising a base storing visual characteristics associated respectively with type object identifiers, said method comprising the following steps implemented by the receiver device: i/ recieving detection data coming from an acquisition device indicating at least one of an identifier of the type object detected in an image, the detection probability of said object and a geographical position; ii/ determining if said image or if a portion of said image comprising the detected type object is present in said detection data; ii_1/ if it has been determined that neither said image, nor a portion of said image comprising the detected type object are present in said detection data, reconstructing the type object as a function of at least the visual characteristics associated with its identifier indicated in the received detection data stored in the base and inserting said reconstructed type object in an overall image as a function of at least said geographical position; ii_2/ if it has been determined that said image or a portion of said image comprising the detected type object is present in said detection data: determining if at least one other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position; if at least one other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position, obtaining of a third image or image portion by combining said image or portion of said image with said other image or image portion and application of a detection processing of type objects of the predefined list on said third image or image portion obtained, determining if one or more objects of the list delivering detection data.
Processing method according to claim 5, whereby the detection, during step ii_2 in said third image or image portion, a type image with a detection probability less than S, triggers the transmission by the receiver to at least one of the two acquisition devices of a request of a new associated image capture in said geographical position.
Processing method according to claim 5 or 6, comprising at least, in step ii_2, one of the two following steps, from among: if no other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position, inserting the image or of image portion in an overall image as a function of at least said geographical position; if at least one other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position, inserting said third image or image portion in an overall image as a function of at least said geographical position.
Processing method according to any one of the preceding claims, whereby the receiver triggers an action coming from step ii_1 or ii_2, as a function of at least the detection data, from among: triggering of an alarm; requesting an image capture additional to said geographical position; determining a command for controlling movable vehicles transporting said acquisition devices, as a function of said geographical position; controlling effectors, as a function of said geographical position.
Processing method according to any one of claims 5 to 8, whereby, in step ii_2/, a decompression processing of said image or image portion is carried out according to a decompression mode selected from among several, as a function of an indication appearing in said received detection data.
Receiver device (2) adapted to receive, via wireless transmission links, detection data coming from a plurality of acquisition devices (1) capturing images, and detecting if type objects defined in a predefined list are present in a captured image, the receiver device comprising a base storing visual characteristics associated respectively with type object identifiers, said receiver device (2) being adapted to receiver detection data coming from an acquisition device indicating at least one of an identifier of the type object detected in an image, the detection probability of said object and a geographical position, to determine if said image or if a portion of said image comprising the detected type object is present in said detection data; said receiver device being adapted to, if it has been determined that neither said image, nor a portion of said image comprising the detected type object are present in said detection data, reconstruct the type object as a function of at least the visual characteristics associated with its identifier indicated in the received detection data stored in the base and to insert said reconstructed type object in an overall image as a function of at least said geographical position; said receiver device being adapted to, if it has been determined if said image or a portion of said image comprising the detected type object is present in said detection data, determine if at least one other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position; and said receiver device is adapted to, if at least one other image or image portion has been received beforehand coming from another acquisition device in detection data indicating the same geographical position, obtain a third image or image portion by combining said image or portion of said image with said other image or image portion and apply a detection processing of said image with said other image or image portion and apply a detection processing of type objects of the predefined list on said third image or image portion obtained, determining if one or more objects of the list delivering detection data.

Description

Domaine technique : L'invention se situe dans le domaine de la détection d'objet d'intérêt sur des images capturées par des dispositifs d'acquisition d'images et trouve un intérêt tout particulier dans les systèmes de télécommunication tactiques, par exemple déployés localement et ponctuellement sur un terrain d'intervention, par exemple sanitaire ou militaire (une zone de catastrophe, géologique ou autre, une zone de conflit etc.), dans lequel des dispositifs d'acquisition, dans des engins mobiles, capturent des images et effectuent une détection/classification d'objets types dans les images, les résultats de cette détection étant ensuite transmis à un dispositif récepteur distant. Technique antérieure : Les caractéristiques de transmission ne sont pas stables dans de tels contextes : elles sont fréquemment rompues sans préavis (par exemple par brouillage intentionnel), ou connaissent des occurrences, bien plus fréquentes que dans les réseaux grands publics classiques, de variations de capacités du réseau de transmission, par exemple en termes de bande passante ou de latence. Les solutions existantes font la détection et suivi de l'objet d'intérêt au niveau du capteur, par des circuits programmés qui réalisent ces fonctions à partir de l'image captée. Ou bien la transmission de l'image en entier prend beaucoup de bande passante, qui n'est généralement pas disponible, ou bien les méthodes de transmission de région d'intérêt (ROI) par les standards de compression d'image/vidéo conduisent à des zones mal délimitées, ou avec des artefacts sur les bords, ou requiert plus de bande passante que disponible. Même dans le cas de transmission de région d'intérêt, souvent le reste de l'image est transmis aussi, à bas débit, ce qui en fait n'est pas nécessaire pour l'application (détection d'un petit objet dans une grande image). La transmission par toutes ces méthodes à travers un réseau à bande passante limitée conduit également à des délais dans la réception de l'information, qui ne sont pas compatibles avec le temps réel nécessaire pour la décision basée sur la détection attendue. Les capteurs optroniques font l'acquisition des images et vidéos très haute résolution pour la détection de cibles d'intérêt. Cependant, la transmission de cette quantité de données est parfois impossible, dans les conditions de réseaux de transmission à bande limitée entre le capteur e tle récepteur. Il existe donc un besoin de permettre une détection plus fiable dans un contexte de transmission instable, i.e même à faible débit. Résumé de l'invention : A cet effet, suivant un premier aspect, la présente invention décrit un procédé de transmission de données de détection d'objets types mis en œuvre par un dispositif émetteur à destination d'un récepteur via au moins une liaison de transmission sans fil, le dispositif émetteur comprenant un bloc de capture d'images et un bloc de détection détectant si des objets types définis dans une liste prédéfinie sont présents dans une image capturée par le bloc de capture et selon quelle probabilité de détection, ledit procédé comprenant, après que le processus de détection ait été effectué sur une image capturée, les étapes suivantes mises en œuvre par le dispositif émetteur : s'il a été déterminé pour l'image considérée une probabilité de détection supérieure à un seuil prédéterminé S pour un objet type et que l'état courant de la liaison de transmission ne vérifie pas des conditions de transmission seuil prédéfinies, alors le dispositif émetteur applique les règles suivantes pour déterminer le contenu à transmettre relativement à l'image : aucune transmission d'une portion de l'image comportant ledit objet type détecté n'est effectuée ;transmission de données indiquant au moins d'un identifiant de l'objet type détecté, la probabilité de détection dudit objet et une position géographique ;si, pour l'image considérée, il n'a pas été déterminé une probabilité de détection supérieur audit seuil prédéterminé S mais qu'il a été déterminé une probabilité de détection comprise entre ledit seuil S et un autre seuil S' prédéterminé strictement inférieur à S et strictement positif, alors le dispositif émetteur applique les règles suivantes pour déterminer le contenu à transmettre relativement à l'image : transmission d'au moins une portion de l'image comportant ledit objet type détecté associée à des données indiquant au moins d'un identifiant de l'objet type détecté, la probabilité de détection dudit objet et une position géographique, et selon lequel avant transmission, une compression d'image est sélectivement appliquée à ladite portion d'image en fonction de l'état courant de la liaison de transmission, y compris pour des états de liaison de transmission ne vérifiant pas lesdites conditions de transmission seuil prédéfinies ; la portion d'image étant, suite à ladite compression, transmise sous forme compressée. Dans des modes de réalisation, un tel procédé comprendra en outre l'une au moins des caractér