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