The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
186 
Side 
overlap 
required 
20 
27 
38 
53 
56 
79 
Net swath 
width 
927 
583 
721 
376 
514 
170 
MPiA 
advantag 
e 
1.59:1 
1.92:1 
3.02:1 
Table 1. Comparison of planned swath width for MPiA and 
conventional operation with varying terrain relief. 
3. DATA PROCESSING SOFTWARE 
3.1 Initial Processing 
Initial processing of the LIDAR data accomplished using 
standard software. Standard tools included Waypoint GrafNav 
for DGPS processing, Leica Geosystems IPAS Pro for 
GNSS/IMU processing, and Leica Geosystems ALS Post 
Processor for point cloud generation. 
3.2 Boresight Calibration 
Boresight calibration was performed using a combination of 
standard and in-house software. Factory boresight calibration is 
set using Leica Geosystems Attune software. Additional 
boresight adjustments were made if needed. Any additional 
adjustment were made using project data from one flight and 
either Terrasolid’s TerraMatch software or other in-house 
software tools in order to maximize accuracy. 
3.3 Filtering for Bare-Earth Model 
Filtering prior to final “delivery” to archive is performed using 
Terrasolid’s TerraScan and TerraModeler software. All point 
clouds are processed to delete redundant data in the overlap 
regions. All points are classified (e.g., bare earth vegetation, 
etc.) and all remaining points after redundant data removal are 
retained for archiving. No thinning of point data is performed 
prior to final storage. In that manner, end customers can order 
data products at a variety of spatial resolutions and still be able 
to access embedded classification information. 
3.4 Finished Product Storage 
After completion of filtering and final data QC, all data is 
ultimately backed up to tape devices. 4 
4. LOGISTICS AND STAFFING REQUIREMENTS 
Logistics and staffing are both important considerations on a 
project of this magnitude. Equipment availability, personnel 
skill sets and utilization, processing workflow and, of course, 
weather are all significant constraints 
4.1 Mission Planning Staffing 
Mission planning consumes roughly 1.5 full-time-equivalent 
staff members. Although this sounds significant, it is in line 
with typical estimates of 10-20% of total job labor. 
4.2 Data Acquisition Staffing 
For each aircraft, two flight crews were used. Each flight crew 
consisted of a pilot and a system operator. Off-duty flight crew 
were used for placement and monitoring of GNSS base stations, 
as well as for copying mission data to backup/transport media. 
Consistent GNSS base station monitoring was considered 
essential, due to the remote locations required. Although 
equipped with large battery supplies capable of up to 4 days’ 
operation, base stations were usually monitored continuously by 
the off-duty flight crew. 
In addition to the 2 flight crew travelling with each aircraft, an 
aircraft mechanic was constantly on-call. Aircraft inspections, 
which occurred every 50 flight hours, might take place at nearly 
any day of the week or time of day, depending on weather 
conditions. Inspections would occur every 5 days if good 
weather prevailed, and the inspection would essentially take the 
place of one flight. Most inspections were performed at the 
field location. 
This staffing level was adequate to support a continuous duty 
cycle of two 5-6 hour missions per day, providing acceptable 
weather conditions. Mission durations as long as 7 hours were 
attained and. in some instances, 3 mission per day were 
accommodated. It should be noted that this “burst mode” could 
only be accommodated for a very short time without 
introducing excessive fatigue in the flight crew. 
Though most of the acquisition was performed with a single 
aircraft, additional aircraft were deployed late in the season to 
maximize data collection for off-season processing. Similar 
staffing was employed for each additional aircraft. 
4.3 Data Logistics 
At the conclusion of each flight, mission data from the ALS50- 
II removable hard drive was copies to two independent stand 
alone 1 TB USB or Firewire drives. Each of these drives could 
accommodate mission data from several flights. Once several 
days’ data was accumulated on these derives, one drive would 
be sent to the processing center. The other would be retained at 
the job site. Due to the remote location of some of the 
acquisition areas, express mail services were not always 
available. As an alternative small-package delivery services by 
bus transport lines was sometimes used. A maximum time 
interval of 3-4 days between data shipments was targeted. 
When a backup drive was received at the processing center, 
data would be immediately checked for proper GNSS/IMU and 
point cloud processing. This process runs approximately in a 
1:1 ratio with flight time given a single workstation. As soon as 
point cloud processing was complete and initial data QC 
performed, the field crew was notified and the duplicate backup 
drive retained at the field site was then freed to be overwritten 
with new data. 
It is interesting to note that incoming data QC was initially 
performed using point clouds that were subsampled 2:1 prior to 
evaluation. However, the additional processing time required 
for non-subsampled point cloud processing was not too 
significant and provided much better insight into the overall 
quality of the incoming data. Therefore, the incoming 
inspection process was modified to include 1:1 processing of all 
data.