Dilution of precision (GPS)
![Understanding the Geometric Dilution of Precision (GDOP) with a simple example. In A someone has measured the distance to two landmarks, and plotted their point as the intersection of two circles with the measured radius. In B the measurement has some error bounds, and their true location will lie anywhere in the green area. In C the measurement error is the same, but the error on their position has grown considerably due to the arrangement of the landmarks.](/Images/godic/202501/18/Geometric_Dilution_Of_Precision.svg1923.png")
![Navigation satellites with poor geometry for Geometric Dilution of Precision (GDOP).](/Images/godic/202501/18/Bad_gdop1924.png")
![Navigation satellites with good geometry for Geometric Dilution of Precision (GDOP).](/Images/godic/202501/18/Good_gdop1924.png")
Dilution of precision (DOP), or geometric dilution of precision (GDOP), is a term used in satellite navigation and geomatics engineering to specify the additional multiplicative effect of navigation satellite geometry on positional measurement precision.