# How maximum elevation figures are calculated for a Joint Operations Graphic

The Calculate Maximum Elevation Figures tool computes the maximum elevation figures for a Joint Operations Graphic (JOG) based on the type of the highest vertical obstruction in a quadrangle. Two obstruction types influence the calculation: man-made and natural terrain. The calculation differs if one type is higher than the other.

## Man-made vertical obstruction

When within a designated quadrangle, a man-made vertical obstruction is higher than the highest natural terrain feature plus an allowance of 46 meters (150 feet) for nonrepresented man-made obstructions, the Calculate Maximum Elevation Figures tool follows this process:

- Determine the elevation of the top of the obstruction above sea level.
- Add the vertical error of the source material to the above figure.
- Round the resultant figure up to the next higher hundred-foot level, if necessary, to achieve a complete value in even hundreds of feet. This final figure is the MEF.

### Example

Elevation of obstruction top (above mean sea level) = 2424 Possible vertical error =+ 250Sum Vertical error + obstruction top elevation = 2674 Raise to next higher 100-foot level = 2700 Maximum Elevation Figure (MEF) = 2^{7}

## Natural terrain feature vertical obstruction

If at least **one** of the following conditions exist within a designated quadrangle:

- A man-made vertical obstruction is lower than the highest natural terrain feature plus an allowance of 46 meters (150 feet) for nonrepresented man-made obstructions.
- A natural terrain feature is the highest point.

The Calculate Maximum Elevation Figures tool will compute maximum elevation figures following this process:

- Determine the elevation of the feature.
- Add the possible vertical error (one contour interval) of the source to the above figure.
- Add a 46-meter (150 foot) allowance for natural or man-made obstructions that are not portrayed because they are below the maximum height at which the specification requires their portrayal by an obstruction symbol.
- Round the resultant figure up to the next higher hundred-foot level, if necessary, to achieve a complete value in even hundreds of feet. This final figure is the MEF.

### Example

Highest Terrain Elevation = 3440 Possible vertical error = 250 Allowance =+ 200Sum highest elevation, vertical error, and allowance = 3890 Raise to the next higher 100-foot level = 3900 Maximum Elevation Figure (MEF) = 3^{9}