For the National Enhanced Elevation Assessment, being performed by Dewberry for sponsoring agencies of the National Digital Elevation Program, new “quality level” (QL) terminology has emerged for elevation data produced by different technologies with different vertical accuracy and horizontal resolution specifications.

These QLs are quickly gaining national acceptance. During several national conferences this year, we have heard participants discuss LiDAR QLs 1, 2, and 3 as though everyone understands the meaning of these terms. Four out of the five QLs are straight forward. Only QL4 digital elevation models (DEMs), produced from existing stereo imagery typically used for digital orthophotos, vary significantly because of different image acquisition flying heights and image pixel resolution.

In case you are unfamiliar with elevation data QLs, you may benefit from studying the table below to get a better understanding.

LiDAR-QLs
These Dewberry Quality Level terms may enter the national lexicon in the future.