3d image sensing system and associated electronic device and time-of-flight distance measurement method

A time-of-flight distance measurement method, comprising:

• emitting a structured light to a target, wherein the structured light has a known pattern;
• receiving a reflected structured light reflected by the target;
• performing a time-of-flight distance measurement to obtain a first distance corresponding to the target based on time-of-flights of the structured light and the reflected structured light, wherein the first distance has a global offset;
• establishing an unknown distance image based on the reflected structured light;
• estimating a disparity between the unknown distance image and a known distance image according to the known pattern, wherein the known distance image is created based on the structured light with respect to a reference object with a known distance;
• calculating a global compensation coefficient based on the disparity;
• and
• compensating the first distance according to the global compensation coefficient to eliminate the global offset.

An electronic device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, wherein the processor, when running the computer program, is configured to:

• performing a time-of-flight distance measurement to obtain a first distance corresponding to a target based on time-of-flights of a structured light having a known pattern projected to the target and a reflected structured light from the target, wherein the first distance has a global offset;
• generating an unknown distance image based on the reflected structured light;
• estimating a disparity between the unknown distance image and a known distance image according to the known pattern, wherein the known distance image is created based on the structured light with respect to a reference object with a known distance;
• calculating a global compensation coefficient based on the disparity;
• and
• compensating the first distance according to the global compensation coefficient to eliminate the global offset.