Ground truth

The term "ground truthing" refers to the process of gathering the proper objective (provable) data for this test.

Examples include cartography, meteorology, analysis of aerial photographs, satellite imagery and other techniques in which data are gathered at a distance.

When the identity and location of land cover types are known through a combination of field work, maps, and personal experience these areas are known as training sites.

The spectral characteristics of these areas are used to train the remote sensing software using decision rules for classifying the rest of the image.

Additional ground truth sites allow the remote sensor to establish an error matrix that validates the accuracy of the classification method used.

Ground truthing ensures that the error matrices have a higher accuracy percentage than would be the case if no pixels were ground-truthed.

Geographic information systems such as GIS, GPS, and GNSS, have become so widespread that the term "ground truth" has taken on special meaning in that context.

The ground truth being estimated by those coordinates is the tip of George Washington's nose on Mount Rushmore.

In practice a smart phone or hand-held GPS unit is routinely able to estimate the ground truth within 6–10 meters.

[5] US military slang uses "ground truth" to refer to the facts comprising a tactical situation—as opposed to intelligence reports, mission plans, and other descriptions reflecting the conative or policy-based projections of the industrial·military complex.