Did you say LiDAR or LADAR?

Early in my career I was a GIS Analyst for a small county government in upstate NY. At the time, the county was acquiring LiDAR data along with orthophotography to augment its GIS database. The plan was to use the LiDAR data to produce 2' elevation contours and digital elevation models for watershed modeling and environmental planning.

A few years later I found myself working for an engineering organization.  My boss asked me if I knew anything about LADAR. I said, do you mean LiDAR? He said, no LADAR, our intelligence customer uses it to identify targets. And this was my first introduction to the use of LiDAR vs. LADAR terminology.

LiDAR stands for Light Detection And Ranging and LADAR stands for LAser Detection And Ranging. They are both acronyms that represent one type of remote sensing technology that can determine the distance between a sensor and an object. Coupled with the known location of the sensor, the range information can be used to produce a highly detailed 3-dimensional map of the object. So why the distinction?

It's a story of community adoption. LiDAR was probably first on the scene when the technology started to emerge in the 1950's. As the technology gained adoption by the military the term LADAR emerged. My guess is that LADAR was popular with the defense community due to its similarity to RADAR (RAdio Detection And Ranging, a similar range finding technology that uses a different type of electromagnetic signals).

Today, you'll find that LiDAR is typically used by folks interested in mapping terrain or collecting information about the atmosphere. Whereas, LADAR is used by people who are interested in locating and characterizing smaller point targets like vehicles or other manmade objects. Either way, it is the same basic technology, only the type of target being 'ranged' is different.