Enhanced distance data acquisition
A distance acquisition method comprising: initializing an optical ranging system, the optical ranging system including a plurality of pixels operable to covert incident light to electrical charges; collecting electrical charges with the plurality of exposed pixels over an integration time, each pixel collecting electrical charges with an amplification and a sensitivity; correlating the electrical charges collected in each pixel to an exposure value for each pixel, the exposure value corresponding to being adequately exposed, over-exposed, or under-exposed; identifying each exposure value for each pixel as being either valid or invalid, wherein a valid exposure value corresponds to an adequately exposed pixel and an invalid exposure value corresponds to an over-exposed or under-exposed pixel; totalling the number of valid exposure value pixels; totalling the number invalid exposure value pixels; determining an exposure ratio, the ratio being the number of pixels with valid exposure values divided by the number of pixels with invalid exposure values; totalling the number of over-exposed pixels; totalling the number of under-exposed pixels; determining an invalid exposure ratio, the invalid exposure ratio being the number of over-exposed pixels divided by the number of under-exposed pixels; and determining an average valid exposure value, the average valid exposure value being the average of the valid exposure values. The method additionally comprises: using the exposure ratio, the invalid exposure ratio and the average valid exposure to optimise the integration time; using the exposure value for each pixel to optimise the amplification and sensitivity for each pixel; and determining distance data from electrical charges collected from at least one of the plurality of pixels.
1. A distance acquisition method comprising:
initializing an optical ranging system, the optical ranging system including a plurality of pixels operable to covert incident light to electrical charges;
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over an integration time, each pixel collecting electrical charges with an amplification and a sensitivity;
correlating the electrical charges collected in each pixel to an exposure value for each pixel, the exposure value corresponding to an adequately exposed pixel, an over-exposed pixel, or an under-exposed pixel;
identifying each exposure value for each pixel as being a valid exposure value or an invalid exposure value, wherein a valid exposure value corresponds to an adequately exposed pixel and an invalid exposure value corresponds to an over-exposed pixel or an under-exposed pixel;
totaling the number of pixels with valid exposure values;
totaling the number of pixels with invalid exposure values;
determining an exposure ratio, the ratio being the number of pixels with valid exposure values divided by the number of pixels with invalid exposure values;
totaling the number of over-exposed pixels;
totaling the number of under-exposed pixels;
determining an invalid exposure ratio, the invalid exposure ratio being the number of over-exposed pixels divided by the number of under-exposed pixels; and
determining an average valid exposure value, the average valid exposure value being the average of the valid exposure values.
2. The method of claim 1 further comprising increasing the integration time when the invalid exposure ratio is less than the validity threshold value and an exposure threshold value, or decreasing the integration time when the invalid exposure ratio is less than the validity threshold value and greater than or equal to the exposure threshold value.
3. The method of claim 1 further comprising:
correlating the average valid exposure value to a scaling factor when the exposure ratio is greater than or equal to a validity threshold value; and
altering the integration time with the scaling factor.
4. The method as in claim 2 or 3 , further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
correlating the electrical charges collected in each pixel to the exposure
value for each pixel, the exposure value corresponding to an adequately exposed pixel, an over-exposed pixel, or an under-exposed pixel; and
increasing the amplification for each under-exposed pixel and decreasing the amplification for each over-exposed pixel.
5. The method as in claim 2 or 3 , further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
correlating the electrical charges collected in each pixel to the exposure
value for each pixel, the exposure value corresponding to an adequately exposed pixel, an over-exposed pixel, or an under-exposed pixel; and
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel.
6. The method of claim 4 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
7. The method of claim 5 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
8. The method of claim 4 further comprising:
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
9. The method of claim 4 further comprising:
correlating the electrical charges collected in each pixel to the exposure value for each pixel, the exposure value corresponding to an adequately exposed pixel, an over-exposed pixel, or an under-exposed pixel;
identifying each exposure value for each pixel as being a valid exposure value or an invalid exposure value, wherein a valid exposure value corresponds to an adequately exposed pixel and an invalid exposure value corresponds to an over-exposed pixel or an under-exposed pixel;
totaling the number of pixels with valid exposure values;
totaling the number of pixels with invalid exposure values;
determining the exposure ratio, the ratio being the number of pixels with valid exposure values to the number of pixels with invalid exposure values;
totaling the number of over-exposed pixels;
totaling the number of under-exposed pixels; and
determining the invalid exposure ratio when the exposure ratio is less than a second validity threshold value, the invalid exposure ratio being the number of over-exposed pixels divided by the number of under-exposed pixels.
10. The method of claim 9 further comprising increasing the integration time when the invalid exposure ratio is less than a second exposure threshold value, or decreasing the integration time when the invalid exposure ratio is greater than or equal to a second exposure threshold value.
11. The method of claim 9 further comprising:
determining an average valid exposure value when the exposure ratio is greater than or equal to the second validity threshold value, correlating the average valid exposure value to a scaling factor; and
altering the integration time with the scaling factor.
12. The method of claim 10 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
increasing the amplification for each under-exposed pixel and
decreasing the amplification for each over-exposed pixel;
increasing the sensitivity for each under-exposed pixel and
decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
13. The method of claim 10 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
increasing the amplification for each under-exposed pixel and decreasing the amplification for each over-exposed pixel;
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
14. The method of claim 11 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
increasing the amplification for each under-exposed pixel and decreasing the amplification for each over-exposed pixel;
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
15. The method of claim 5 further comprising:
correlating the electrical charges collected in each pixel to the exposure
value for each pixel, the exposure value corresponding to an adequately exposed pixel, an over-exposed pixel, or an under-exposed pixel;
identifying each exposure value for each pixel as being a valid exposure value or an invalid exposure value, wherein a valid exposure value corresponds to an adequately exposed pixel and an invalid exposure value corresponds to an over-exposed pixel or an under-exposed pixel;
totaling the number of pixels with valid exposure values;
totaling the number of pixels with invalid exposure values;
determining the exposure ratio, the ratio being the number of pixels with valid exposure values to the number of pixels with invalid exposure values;
totaling the number of over-exposed pixels;
totaling the number of under-exposed pixels; and
determining the invalid exposure ratio when the exposure ratio is less than a second validity threshold value, the invalid exposure ratio being the number of over-exposed pixels divided by the number of under-exposed pixels.
16. The method of claim 15 further comprising increasing the integration time when the invalid exposure ratio is less than a second exposure threshold value, or decreasing the integration time when the invalid exposure ratio is greater than or equal to a second exposure threshold value.
17. The method of claim 15 further comprising:
determining an average valid exposure value when the exposure ratio is greater than or equal to the second validity threshold value, correlating the average valid exposure value to a scaling factor; and
altering the integration time with the scaling factor.
18. The method of claim 15 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
increasing the amplification for each under-exposed pixel and decreasing the amplification for each over-exposed pixel;
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.
19. The method of claim 16 further comprising:
directing incident light to the plurality of pixels;
collecting electrical charges with the plurality of pixels over the integration time, each pixel collecting electrical charges with the amplification and the sensitivity;
increasing the amplification for each under-exposed pixel and decreasing the amplification for each over-exposed pixel;
increasing the sensitivity for each under-exposed pixel and decreasing the sensitivity for each over-exposed pixel; and
determining distance data from electrical charges collected from at least one of the plurality of pixels.