1. LP DAAC OPeNDAP Services
Jason Werpy
LP DAAC Enterprise Architect
SGT, Inc., Contractor to the USGS EROS Center
*Work performed under USGS contract G15PD00766

2. OPeNDAP – The base of LP DAAC Data access
Tiered Concept
LP DAAC created a tiered approach to data access

3. A Quick Aside – HTTP access to everything
OPeNDAP utiilzes HTTP to access data, so LP DAAC decided to deploy all the components for data access as HTTP services as well.
Why HTTP services?
Simple
Standard based protocol
Securable
Dynamic interaction methods (get/post, etc.)
Stream based data delivery

4. OPeNDAP – The base of LP DAAC Data access
Data Access methods
OPeNDAP - Open-source Project for a Network Data Access Protocol. Provides a direct way of subsetting LP DAAC data from our Data Pool.

5. LP DAAC OPeNDAP Deployment
Hyrax was chosen for the LP DAAC deployment because of its capabilities for handling of MODIS tile data.
Due to the uniform tiled nature of the LP DAAC’s MODIS data, we chose to aggregate data based on date.
Due to the configuration of the ECS data pool we chose to programmatically create and update our aggregation files instead of using the scanning based aggregation capabilities.
Aggregation scripts are available at ECC, contact me for further details.
LP DAAC OPeNDAP Services

6. LP DAAC OPeNDAP Deployment
To handle large volumes of data access LP DAAC deployed a cluster of servers to provide OPeNDAP services.

7. OPeNDAP Data Access
Data Services
Middleware
API UI

8. OPeNDAP Data Access
Data Services
Middleware
API UI

9. LP DAAC OPeNDAP Data Access
link
Data Services
Middleware
API UI

10. OPeNDAP Data Access Access and extract discrete subsets
Spatial
Band/Layers
Temporal (from aggregation)
Request data via URL
Returns data that the user intends to use!
Reduces time spent downloading and processing
Minimizes the amount of data downloaded
Converts the data format if desired
Data Services
Middleware
API UI

11. OPeNDAP Data Access OPeNDAP request: Return:
Return:
{ "name": "h11v04.ncml",
"attributes": [ {"name": "HDF_GLOBAL","attributes": [ {"name": "HDFEOSVersion", \
"value": ["HDFEOS_V2.9"]} ] } ],
"leaves": [ { "name": "sur_refl_b01", "type": "Float32", "attributes": [
{"name": "coordinates", "value": ["Latitude Longitude"]}, {"name": "long_name", "value": ["Surface_reflectance_for_band_1"]}, {"name": "units", "value": ["reflectance"]},
{"name": "scale_factor_err", "value": [ ]}, {"name": "add_offset_err", "value": [ ]}, {"name": "calibrated_nt", "value": [5]},
{"name": "orig_scale_factor", "value": [ ]}, {"name": "orig_add_offset", "value": [ ]},
{"name": "_FillValue", "value": [-28672]}, {"name": "valid_min", "value": [ ]}, {"name": "valid_max", "value": [ ]},
{"name": "grid_mapping", "value": ["MOD_Grid_250m_Surface_Reflectance_eos_cf_projection"]}
], "shape": [1,11,11],
"data": [[[0.5359, , , , , , , , , , ],
[0.5759, , , , 0.432, , , , , 0.455, 0.446],
[0.4594, , , , , , , , , , ],
[0.5831, , , , , , 0.612, , , 0.332, ],
[0.6329, , , , , 0.612, , , , , ],
[0.6092, , , , , , , , , , ],
[0.5712, , , , , , , , , , ],
[0.5737, , 0.524, , , , , , , , ],
[0.5606, , , , , 0.343, 0.26, 0.26, , , ],
[0.5883, , , , 0.343, , 0.626, 0.626, , , ],
[0.5435, , , , , , 0.626, , , , ]]] } ], "nodes": [] }
Data Services
Middleware
API UI

12. OPeNDAP Data Access OPeNDAP URLs are complex Need to know: Syntax
Product name
Layer name
Time
Geolocation
Tile locations (H & V) – Data is aggregated over time by tile
Pixel location (Ydim & Xdim)
Data Services
Middleware
API UI

13. With the OPeNDAP in Place what can be done?
Using these building blocks the LP DAAC (or anyone who wants to really) can build new interfaces and systems like….

14. AppEEARS
Application for Extracting and Exploring Analysis Ready Samples
Web application interface for accessing and extracting LP DAAC’s tiled MODIS and WELD data
Data Services
Middleware
API UI

15. https://lpdaacsvc.cr.usgs.gov/appeears/
AppEEARS location
Data Services
Middleware
API UI

16. Questions?
Questions?
Data Services
Middleware
API UI

17. AppEEARS Built on top of services and tools Capabilities
Easy access and selection of MODIS and WELD land data
Extracts pixel values for sample point locations
Data exploration and interaction
Dynamic Graphs
Tables
Download Bundle
Analysis-ready data
Data Services
Middleware
API UI

18. For More Information about our services
Subscribe to our listserv:

19. BEDI – LP DAAC Response Middleware Web Services
Tilemap – Coverts Latitude and Longitude values into tile and pixel values for datasets located on a common grid structure.
Fromjulian – Converts dates from a Julian date format to a mm-dd-yyyy format.
Tojulian – Converts dates from a mm-dd-yyyy format to a Julian date format of the number of days since
Product (coming soon!) – Service that provides information about the different products available from the LP DAAC.
Inventory – Service that returns information about the granules in the LP DAAC inventory. Powered by NASA Common Metadata Repository (CMR).
Data Services
Middleware
API UI