Opaque cloud detection
AssigneeSandia Corporation
InventorJohn K. Roskovensky
Life of this patent
Estimating the term…
Abstract
A method of detecting clouds in a digital image comprising, for an area of the digital image, determining a reflectance value in at least three discrete electromagnetic spectrum bands, computing a first ratio of one reflectance value minus another reflectance value and the same two values added together, computing a second ratio of one reflectance value and another reflectance value, choosing one of the reflectance values, and concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.
Claims15
A method of detecting clouds in a digital image, the method comprising the steps of:
- for an area of the digital image, determining a reflectance value R1 in a discrete electromagnetic spectrum band from 400 nm to 460 nm, a reflectance value R2 in a discrete electromagnetic spectrum band from 630 nm to 690 nm and a reflectance value R3 in a discrete electromagnetic spectrum band from 830 nm to 890 nm;
- computing in a first computing step a first ratio of the R3 reflectance value minus the R1 reflectance value and the same two values added together;
- computing in a second computing step a second ratio of the R3 reflectance value and to the R2 reflectance value;
- choosing the R2 reflectance value;
- and
- concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.
A method of detecting the existence of snow in a digital image, the method comprising the steps of:
- for an area of the digital image, determining a reflectance value R1 in a discrete electromagnetic spectrum band from 400 nm to 460 nm and a reflectance value R2 in a discrete electromagnetic spectrum band from 830 nm to 890 nm;
- computing a ratio of one reflectance value selected from R1 and R2 minus another reflectance value selected from R1 and R2 and the same two values added together;
- and
- concluding that snow exists in the area if the result of the computing step falls outside a predetermined range.
Computer software stored on a computer-readable medium for detecting clouds in a digital image, said computer software being embodied on a computer readable medium and comprising:
- software stored on a computer-readable medium that, for an area of the digital image, determines a reflectance value in at least three discrete electromagnetic spectrum bands;
- software stored on a computer-readable medium computing a first ratio of one reflectance value minus another reflectance value and the same two values added together;
- software stored on a computer-readable medium computing a second ratio of one reflectance value and another reflectance value;
- software stored on a computer-readable medium computing one of the reflectance values;
- and
- software stored on a computer-readable medium for concluding that an opaque cloud exists in the area if the result of each of the three computing steps falls within three predetermined ranges.
Computer software stored on a computer-readable medium for detecting clouds in a digital image, said computer software being embodied on a computer readable medium and comprising;
- software stored on a computer-readable medium that, for an area of the digital image, determining a reflectance value in at least two discrete electromagnetic spectrum bands;
- software stored on a computer-readable medium computing a ratio of one reflectance value minus another reflectance value and the same two values added together;
- and
- software stored on a computer-readable medium for concluding that snow may exist in the area if the result of the three computing step falls outside a predetermined range.
Dependencies are inferred from the claim text.