A one-dimension position measurement system comprising: - a first ruler, on which is applied a first one-dimension code, - a second ruler, on which is applied a second one-dimension code, - a camera for acquiring simultaneously a picture of a portion of the first one-dimension code and of a portion of the second one-dimension code, and - some processing means, said second ruler being disposed parallel to said first ruler, one end of said first ruler being tied to one end of said second ruler, the other end of said first and second rulers being free, said first and second rulers being made of material having different temperature expansion coefficients, characterized in that said first ruler and said second rule comprise each an absolute code, said one-dimension position measurement system comprising means to project horizontally said pictures so as to provide a first and second regular signal which are suitable to perform an interpolation on respectively said first and second one-dimension code, and in that said processing means are implemented for - dividing horizontally the acquired picture depicting the portion of code of one of said first or second one-dimension position into a top half-pictures of height h and a bottom half-picture of height h, - computing a precise position pt of the portion of code in said top half-picture, - computing a precise position p b of the portion of code in said bottom half-picture, and - computing the tilt angle θ between said camera and said first and second rulers from: θ = arctan Δx / h where Δx=p t -p b, - calculating a temperature independent position of said camera with reference to said first and second rulers, the influence of the computed tilt angle θ being removed in the calculation. and in that, at a temperature T, said processing means are implemented for computing a position x b0, x b0 being the position of the portion of the first one-dimension code with respect to the camera when the position of the second one-dimension code with respect to the camera is null, and further in that said processing means are implemented for computing said temperature independent position x from the relation: x = α b x a − α a x B α b − α a, with x B =x b -x b0 where x a is the measured position of the portion of said first one-dimension code with respect to the camera, x b is the measured position of the portion of said second one-dimension code with respect to the camera, α a is the temperature expansion coefficient of said first ruler and α b is the temperature expansion coefficient of said second ruler. - a first ruler, on which is applied a first one-dimension code, - a second ruler, on which is applied a second one-dimension code, - a camera for acquiring simultaneously a picture of a portion of the first one-dimension code and of a portion of the second one-dimension code, and - some processing means, - dividing horizontally the acquired picture depicting the portion of code of one of said first or second one-dimension position into a top half-pictures of height h and a bottom half-picture of height h, - computing a precise position pt of the portion of code in said top half-picture, - computing a precise position p b of the portion of code in said bottom half-picture, and - computing the tilt angle θ between said camera and said first and second rulers from: θ = arctan Δx / h where Δx=p t -p b, - calculating a temperature independent position of said camera with reference to said first and second rulers, the influence of the computed tilt angle θ being removed in the calculation.