A unitless figure of merit expressing the relationship between the error in user position and the error in satellite position. For most purposes and GPS receivers, PDOP values considered good for positioning are small, such as 3. Values greater than 7 are considered poor.…
Electromagnetic Spectrum
Energy from sunlight is called the electromagnetic spectrum. Energy in the form of light waves travels from the sun to Earth. Light waves travel similarly to waves traveling across a lake. The distance from the peak of one wave to the peak of the next wave is the wavelength. Wavelengths are measured in micrometres (µm) or nanometers (nm). One µm is one-millionth of a meter or 1,000 nm. A nanometer is one-billionth of a meter. The visible region (light seen …
Remote Sensing Resampling Methods
When an image is created through remotely sensed data, it needs to undergo some form of validation procedure using observational and/or sampling techniques. Failure to do so will reduce the confidence in the final product. The following are examples of remote sensing resampling methods:
Nearest neighbor
Nearest neighbor is a resampling method used in remote sensing. The approach assigns a value to each “corrected” pixel from the nearest “uncorrected” pixel. The advantages of nearest neighbor include simplicity and the ability …
National Map Accuracy Standards (NMAS)
The National Map Accuracy Standards (NMAS) were established in 1941 by the U.S. Bureau of the Budget to set accuracy standards for all federally produced maps. The current standards were revised in 1947.
Scale and the NMAS