SRGE internal online workshop 28 July 2020

1. NTL Variation During
Covid-19 Spread
Moataz Kilany

2. Introduction
• Covid-19 spread response patterns In USA.
– Calls for staying home.
– Policies to shut down businesses
(46 states).
• Reduced activities in accordance with new
safety measures.

3. Introduction
• Night-Time Light Analysis (NTL).
– Can study patterns of change in human
activities.
– Assessing different Covid-19 response patterns
in different administrative areas.

4. NTL Data
• Nasa VIIRS Black Marble.
– Latest advancement in NTL imagery.
– Highest spatial resolution in NTL (500 m).
– Highest temporal resolution (Daily Images
since 2012).
– High QA quality.
• Cloud detection.
• Atmospheric effect elimination.
• Diffused light elimination.
– Open access
(https://ladsweb.modaps.eosdis.nasa.gov/search/)

5. Proposed Model
Multi-date
Black
Marble
Images
Cloud
Removal
Geo-
referencing
Image
composition
/ Mosaicking
Change
Detection
(Differencing)
Mapping &
Change
Evaluation

6. Images Acquisition
216 images/days
- December 2019 To July 2020
- Tri-State Area (Newyork / Newjersey &
Connecticut)
Set1
Set2
Set15
14 Days
14 Days
14 Days

7. Cloud Removal / Masking
Cloud Detection
Cloud Removal
Image
Composition

8. Cloud Removal / Masking
Cloud Detection
Cloud Removal
Image
Composition

9. Cloud Removal / Masking
26/12 02/01 21/01 30/01 23/02 18/03
23/04 29/04 14/05

10. Change Detection / Differencing
Set 1 Set 2
Set 1 Set 2
Set 14 Set 15
Thresholding /
Classification
Dec, 1 Jan, 21 Jan, 21 Feb, 23
Feb, 23 March, 18 April, 1 April, 23 April, 29 May, 14

11. Limitations / Future work
26/12 02/01 21/01 30/01 23/02 18/03
23/04 29/04 14/05
Distortions / Likely
moon light effect

12. Limitations / Future work
- Including June analysis with previous results.
- Establishing statistical / Numerical assessment for light
intensity across pandemic time-span.
- Using Blackmarble latest product with moon light eliminated
- Product VNP46A2 (Will be available before summer
ends).

13. Thank you