SOLAR NYCSean C. Ahearn
CARSI Hunter College – CUNYNGAC Meeting, September 23, 2010
CARSI, 2010 -- preliminary LIDAR data
Hunter College - CUNY
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CollaborationsThese are the four project partners that are working on the SOLAR NYC Project. These partners have signed an MOU outlining specific roles and responsibilities.
Our utility and state partners. These groups provide financial and advisory support.
We work with these City agencies on various solar initiatives. They provide expertise on how to integrate solar into their processes and programs.
Sustainable CUNY on behalf of the City University of New York
Mayor’s Office of Long-Term Planning and Sustainability
NYC Solar America Cities Advisory Board
• Eight industry representatives • Ten non-profit solar/energy advocacy organizations • Six additional government agencies
SOLAR NYC: The Players
CUNY Players
CARSI TeamSean C. AhearnYo Jin AhnJake GarciaGordon GreenYlli Kellici
Sustainable CUNYTria CaseAlison KleinNoah Ginsburg
LiDAR as input to Solar Insolation Model
• Create surface model for City– Testing of resolution– 1 foot
• Use LIDAR to examine roof morphology– Useable roof area
• Use ESRI insolation tool• Calibrate with installation data
SOLAR NYC WEB Portal
LiDAR Coverage for New York City (1119 Tiles, > 15 billion points)
LiDAR Points Overlaid with Orthophoto and Signal Intensity
View from North-East: Columbus Circle, Central Park South-West Manhattan, New York City
LiDAR Point Clouds Displayed by Height Coloration
Quality Assurance of LiDAR
• Minimum density of 8 points per m2 (QL 1)• Accuracy 9-10 cm RMSE Raw LAS format 1.2
including X, Y, Z and Intensity information• DSM• Bare Earth• Classification (ASPRS)
– 1 Unclassified– 2 Bare Earth– 7 Noise– 12 Overlap
Ground Control for QA (2cm RMSE)
• Manhattan: 198 points• Queens: 260 points• Brooklyn: 450 points• Bronx: 290 points• SI: 190
Density of 0.74 = 8 pts per m2
Ground Control for Manhattan
RMS
• LiDAR and 196 Ground Control Points
• Average Difference = -1.64 cm (error in the Z of the airplane derived from airborne RTK GPS?)
• RMSE = 6.69 cm
LiDAR Data Quality Check Points
1. Artifacts or Outliers by Profile Analysis 2. Check ground survey points placed non-ground
Bare Earth only Bare Earth and Unclassified
QA 3 : Check Classification
Using just bare earth, an error of 4 feet was found due to misclassification
Digital Elevation Model (1ft)
Building Extraction
Digital Surface Model
Application Example 1: Building Extraction
Example.2: Separation and Quantification of the Slant Rooftops from a LiDAR Point Clouds