The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
Figure 1. Comparison of conventional and MPiA 
operating envelope 
2. PROJECT OVERVIEW 
2.1 Project Location and Coverage Area 
The project area consists of the entire Alberta province 
(-640000 km 2 ), along with adjacent parts of British Columbia 
and Saskatchewan provinces. In total, the project area 
encompasses 750,000 km 2 . In addition to its sheer size, this 
project is distinguished by the fact that it is largely an “on-spec” 
project. Although some portions of the collected data was 
flown for specific clients, the remainder of the area is being 
flown without a specific client. 
A small portion of the data (-5%) had been previously flown 
and processed, and was therefore available from archive. The 
progress toward acquisition and processing of the remaining 
portions of this project are the subject of this investigation. 
2.2 Project Duration 
The project was started in May 2007 and is multi-year in nature, 
owing to its large size and restrictions in operating season. The 
data being collected covers both mountainous and prairie areas. 
For the mountainous areas, the flying season is limited to July 
and August in order to maximize the area uncovered by 
snowpack. Despite this limited flying season, some areas flown 
are permanently covered with snow and/or ice. For prairie 
areas, the flying season is substantially longer, starting in May. 
Permanent seasonal snow cover begins in October, at which 
point operations are suspended for the year. In each flying 
season, roughly one-third of the project is completed. 260 
flights were completed in 2007. 200 of these flights were made 
using a single aircraft. The remaining 60 flights were made 
using aircraft and LIDAR systems from a subcontractor. These 
additional flight were made primarily to ensure a full supply of 
data to be processed over the non-flying season. 
2.3 Project Specifications 
Since the project is being done primarily “on spec”, there is 
some freedom to determine specifications for point density and 
accuracy. However, the specifications selected are fairly 
typical for medium or large-area jobs. The objective is to create 
a bare-earth DEM with a point spacing of 1 to 1.5 meters. 
Accuracy objectives are RMS values of 20 cm Z and 50 cm XY. 
2.4 Aircraft Used 
The aircraft used for the majority of the data acquisition was a 
Cessna 335. This is an unpressurized aircraft with twin piston 
engines and propeller propulsion. The was no optical window 
through which the LIDAR system had to fire, and thus 
refraction corrections for an air/glass/air interface was not 
needed. Other similar aircraft were also used at points in the 
project. 
Figure 2. Cessna 335 survey aircraft 
2.5 LIDAR System Used 
Figure 3. Leica Geosystems ALS50-II LIDAR system 
The LIDAR system employed was a Leica geosystems ALS50- 
II, and was equipped for MPiA operation. The ALS50-II 
system is capable of pulse rates up to 150 kHz in both 
conventional and MPiA modes. In MPiA mode, the system 
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