Once out of the cave all of the data must be reduced or analyzed. The cave data consisting of compass bearings, distances, and inclinations must be put into a form that allows a map to be drawn. The major problem with that data collected in the cave is that the distances measured in the cave are SLOPE DISTANCES and not HORIZONTAL DISTANCES which is the distance that must be drawn on the map.

Using trigonometry, and the data collected in the cave, the slope distances can be reduced to horizontal distances. This reduction is given by the formula: horizontal distance = Slope distance times the Cosine of the inclination. For example, if the distance measured from one station to another is 100 feet but the passage was going down a slope at a 30 degree angle, the horizontal distance would be 86.6 fee [100 x COS(30) = 100 x .866].

Similarly the depth of each station can be calculated using trigonometry. In this case, the rise or fall from station to station is given by the formula: Rise = Slope distance times the Sin of the inclination. In the example above, the second station would be 50 feet below the other station [100 x SIN(30) = 100 x .500]. By using trigonometry on each of the 27,000 sets of readings, the true horizontal distances and depths of each station in the cave can be calculated relative to a known point (the cave entrance).

Of course, al these calculations provide the information necessary to draw an accurate map if all the readings in the cave were done with perfect accuracy. This is never the case, especially when the instruments have to be read under the conditions found in the cave. To correct such errors, complex statistical corrections (called LEAST SQUARES) are performed on the analyzed data and in recent years electronic underground radio location devices called cave radios have been used to help correct errors in the cave surveys.

The Wind Cave Map today is produced by feeding all the survey data into a computer where complex trigonometric calculations are performed and the statistical corrections are done taking into consideration the locations proved by cave radios. It is the most accurate map of Wind Cave that can be produced by modern technology. Yet despite such marvelous advances, the actual surveying process still requires long hours in the cave, crawling and climbing around, searching for that ever elusive discovery...and the cavers who explore Wind Cave would not want it any other way.