Unfortunately, much LIDAR data has been delivered in text format (American Standard Code for Information Interchange, ASCII) rather than the rich binary LAS format. Many agencies now have disk drives of LIDAR, in ASCII format, on the shelf that accompanied more familiar LIDAR-derived products such as gridded Digital Elevation Models (DEMs) and digital contour files. So is there value in these ASCII LIDAR files?
To this question, I would say most emphatically yes! Generally the value will be limited when compared to a full LAS data set but, in most cases, there will be information above and beyond the DEMs and contours that were delivered as standard products.
We recently visited a municipality that has been using gridded elevation data derived from LIDAR. They have various files of ASCII format LIDAR data that were delivered with the project but have remained unused. We were asked to have a look at these data to see if useful additional information could be derived. Upon inspecting the files, I noted that they have data sets labeled as “Ground” files and separate files of “non-Ground.” LP360 includes an import function for reading ASCII files so I decided to attempt to use this as a method to create a merged LAS file of ground and non-ground. I first imported the ground file (the import tool is under the LP360 drop-down on the main LP360 toolbar in the ArcGIS® version and under the File menu item for LP360 for Windows®). Note that if the files are different, you will need to import them one at a time.