Foreign object detection with surfel maps

A system comprising:

• one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising:
• receiving sensor data representing reflection characteristics of electromagnetic waves in an operating environment of an autonomous vehicle;
• obtaining a surfel map representing a portion of the operating environment of the autonomous vehicle, wherein a plurality of surfels in the surfel map are associated with reflection data representing one or more reflection characteristics of a surface in the operating environment represented by the surfel map;
• computing a reflection distance between (i) reflection characteristics of surfaces in the operating environment detected by the sensor data and (ii) reflection characteristics of surfels in the surfel map representing the surfaces In the operating environment detected by the sensor data;
• determining that the reflection distance between (i) reflection characteristics of a surface detected by the sensor data and (ii) reflection characteristics of a surfel in the surfel map representing the surface detected by the sensor data satisfies a threshold;
• and
• in response, detecting a foreign object at a location in the operating environment corresponding to the surfel in the surfel map, wherein detecting the foreign object comprises:
• detecting, from the sensor data, an elevation of the surface corresponding to the reflection characteristics having the reflection distance that satisfies the threshold;
• obtaining, from the surfel map, an elevation of the surfel corresponding to the surface detected by the sensor data;
• and
• computing a height difference between the elevation of the surfel and the elevation of the surface.

One or more non-transitory computer storage media encoded with computer program instructions that when executed by one or more computers cause the one or more computers to perform operations comprising:

• receiving sensor data representing reflection characteristics of electromagnetic waves in an operating environment of an autonomous vehicle;
• obtaining a surfel map representing a portion of the operating environment of the autonomous vehicle, wherein a plurality of surfels in the surfel map are associated with reflection data representing one or more reflection characteristics of a surface in the operating environment represented by the surfel map;
• computing a reflection distance between (i) reflection characteristics of surfaces in the operating environment detected by the sensor data and (ii) reflection characteristics of surfels in the surfel map representing the surfaces In the operating environment detected by the sensor data;
• determining that the reflection distance between (i) reflection characteristics of a surface detected by the sensor data and (ii) reflection characteristics of a surfel in the surfel map representing the surface detected by the sensor data satisfies a threshold;
• and
• in response, detecting a foreign object at a location in the operating environment corresponding to the surfel in the surfel map, wherein detecting the foreign object comprises:
• detecting, from the sensor data, an elevation of the surface corresponding to the reflection characteristics having the reflection distance that satisfies the threshold;
• obtaining, from the surfel map, an elevation of the surfel corresponding to the surface detected by the sensor data;
• and
• computing a height difference between the elevation of the surfel and the elevation of the surface.