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Surdex Corporation■ Surdex headquartered in St. Louis, MO area■ Over a half-century of photogrammetric mapping
~100 employees8 aircraft – 4 Cessna 441 (Conquest) Turbine Aircraft3 Intergraph Digital Mapping Cameras (DMC)1 UltraCam Xp Wide Angle5 film camerasLeica ALS 50-II LiDAR
■ Very progressive R&DLarge amount of proprietary algorithms and softwareFocus on cost-efficiency and performance
LiDAR ProcessingGPS/IMU
ProcessingIMU
DataReductionGC Check
Position
Attitude
GPS
LASERMeasurements(Range, Angle, Time)
Classification
X,Y,Z
Point Cloud
Stereo QC / Edit
Classified Points (Bare-earth, veg/building)
Stereo
Images
DataThinning
TIN
Break-
lines
DTM
Surface
AUTOMATIC
MANUAL2D Edit
TIN
LASER Intensity,
RGB
Ortho Photos
First Return DEM
Bare Earth DEM Calculations
1. Identify man made structures
• Determine ground elevation at edges
2. Identify vegetated areas
• Search for ground points within area
3. Identify open areas
4. Interpolate between available points
5. Filtering and clean-up
Bare Earth DEM
Automatically extracted Bare Earth DEM
• Ground surface with vegetation and man-made structures removed
• Critical for terrain and hydrology modeling
Bare Earth DEM with 1 meter contours
Raw vs. Edited LiDAR Contours
Contours from raw LiDAR data Contours from raw LiDAR data with photogrammetric edits
Types of LiDAR DTM & Contours
Level I• Classified to bare earth, automated generation
Level II• Classified to bare earth
• Automated, minimal cartographic edits
Level III• Classified to bare earth
• Break lines added to hydrology
• Similar cartographic edits of Level II
Level IV (Specified contour accuracy)• Classified to bare earth
• Full break line enhancement
• Full cartographic edits
Level 1-2 surface
Level 1
Level 1 Surface and Contours
Level 2 Contours
Level 2 Surface and Contours
Level 3 Hydro Breaklines
Level 3 surface
Level 1-2 Surface Level 3 Surface
Level 3 Surface and Contours
Level 3 Contours
Project Area, St. Louis MO
Contours from Bare Earth
Hydro and terrain breaklines
Full break line enforced contours
Full break line enforcement
Contours from LiDAR Data
■ Understand the various data available
■ Understand the cost associated with additional editing and processing
■ Discuss the project requirements with your LiDAR provider
■ Get ready for A LOT of data!
