Earth observation / Vegetation condition
MODIS 16-day vegetation indices over Tbilisi
Microsoft Planetary Computer hosts NASA MOD13Q1 Collection 6.1 as STAC items and signed cloud-optimized GeoTIFF assets. The Tbilisi tile supplies 250-metre 16-day NDVI, EVI, red/NIR/blue/MIR reflectance, viewing and solar angles, composite day, a packed VI-quality layer and a four-class pixel-reliability layer. Metadata search and short-lived SAS signing are public, but the collection itself declares license=proprietary and attributes NASA LP DAAC as licensor.
Provenance and access
How the data is reached
Unauthenticated STAC search. Asset URLs must be signed through the public Planetary Computer SAS endpoint; signed URLs are temporary. The signed TIF URL returned HTTP 200 during validation.
STAC collection declares proprietary; NASA LP DAAC is listed as producer/licensor/processor. Follow LP DAAC product citation and Planetary Computer terms rather than assuming public-domain status.
Tbilisi MOD13Q1 search
https://planetarycomputer.microsoft.com/api/stac/v1/search?bbox=44.70,41.67,44.88,41.80&collections=modis-13Q1-061&datetime=2026-06-01T00:00:00Z/2026-07-22T23:59:59Z&limit=2 ↗- Method
- GET
- Format
- GeoJSON/STAC JSON
- Authentication
- None
- Method
- GET
- Format
- STAC Collection JSON
- Authentication
- None
- Method
- GET
- Format
- JSON
- Authentication
- None
Returns temporary signed href
Field-level detail
What is actually returned
MOD13Q1 STAC Item
Composite identity, interval and tile metadata.
| Field / path | Type | Null? | Example | Meaning | Freshness |
|---|---|---|---|---|---|
id / collection / bbox / geometry | string / string / bbox / polygon | No | MOD13Q1.A2026145.h21v04.061.2026163134454 / modis-13Q1-061 | Composite identity and coverage | reference |
properties.datetime | null | Yes | null | Single instant is unused because item has an interval | reference |
properties.start_datetime / end_datetime | ISO datetime | No | 2026-05-25T00:00:00Z / 2026-06-09T23:59:59Z | 16-day composite interval | reference |
properties.platform / instruments[] | string / array | No | terra / [modis] | Satellite platform and sensor | reference |
properties.modis:tile-id / horizontal-tile / vertical-tile | string / integers | No | 51021004 / 21 / 4 | MODIS sinusoidal tile identity | reference |
properties.eo:cloud_cover | percentage number | No | 0 | Catalog cloud-cover metadata | derived |
assets | object | No | 15 asset keys | COG measurements, HDF source, preview and tile service | reference |
Vegetation and supporting raster assets
Each COG has href, TIFF media type, data role, title and raster:bands metadata.
| Field / path | Type | Null? | Example | Meaning | Freshness |
|---|---|---|---|---|---|
250m_16_days_NDVI | int16 COG; scale 0.0001; 250m | No | stored 7234 → NDVI 0.7234 | Normalized Difference Vegetation Index | historical |
250m_16_days_EVI | int16 COG; scale 0.0001; 250m | No | EVI raster | Enhanced Vegetation Index | historical |
250m_16_days_red_reflectance / NIR_reflectance / blue_reflectance / MIR_reflectance | COG rasters | No | four reflectance assets | Surface reflectance inputs and context bands | historical |
250m_16_days_VI_Quality | uint16 COG; 250m | No | packed quality bits | Detailed vegetation-index QA flags | reference |
250m_16_days_pixel_reliability | int8 COG; 250m | No | 0 | Simplified pixel reliability0 good; 1 marginal; 2 snow/ice; 3 cloudy | reference |
250m_16_days_composite_day_of_the_year | COG raster | No | day-of-year values | Observation date selected within composite | historical |
250m_16_days_relative_azimuth_angle / sun_zenith_angle / view_zenith_angle | COG rasters | No | angle layers | Acquisition/view geometry | reference |
hdf / rendered_preview / tilejson | HDF / image / JSON assets | No | source product and visualization helpers | Original product, preview and tiled rendering metadata | reference |
common asset metadata | href,type,roles,title,raster:bands[] | No | COG URL; scale; data_type; spatial_resolution | Download and pixel-decoding metadata | reference |
Representative evidence
Sample records
Tbilisi MODIS vegetation composite
Retrieved 2026-07-22 14:04 Asia/Tbilisi
{"id":"MOD13Q1.A2026145.h21v04.061.2026163134454","properties":{"start_datetime":"2026-05-25T00:00:00Z","end_datetime":"2026-06-09T23:59:59Z","platform":"terra","modis:horizontal-tile":21,"modis:vertical-tile":4},"NDVI":{"title":"16 day NDVI","scale":0.0001,"data_type":"int16","spatial_resolution":250},"pixelReliabilityClasses":{"0":"good","1":"marginal","2":"snow/ice","3":"cloudy"}}Boundaries
Reliability, caveats, and privacy
What held up
- Live search returned h21v04 for the Tbilisi bbox
- A signed asset URL returned HTTP 200
- Temporal extent starts in 2000, supporting long comparisons
What can go wrong
- Apply scale 0.0001 to NDVI/EVI stored integers
- Use QA and pixel-reliability layers; do not compare cloudy/snow pixels as vegetation change
- 250m pixels mix multiple urban surfaces
- Temporary SAS signatures expire
- Collection explicitly says proprietary
Cross-source possibilities
Ideas using this source
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Primary pages and documentation
https://planetarycomputer.microsoft.com/api/stac/v1/collections/modis-13Q1-061- DocumentationNASA MOD13Q1 product page ↗
https://lpdaac.usgs.gov/products/mod13q1v061/ - DocumentationPlanetary Computer data-license guidance ↗
https://planetarycomputer.microsoft.com/docs/overview/about/#data-licenses