FAQs

Here are our answers to some frequently asked questions from users.

I never received an account invitation email. What should I do?

Please check your spam inbox. If you still don't see the invitation email, reach out to [email protected] for assistance.

Can I browse the catalog even if I haven't ordered any data?

Yes! Please email [email protected] requesting a demo account.

You can also check out our Open Data Program, which you won't need an account to access.

What is STAC?

STAC stands for "SpatioTemporal Asset Catalog". It's a standardized framework for indexing, cataloging, and describing geospatial data. It makes Hydrosat data easier to work with, especially if you're integrating it with data from other sources.

What do the different assets in a STAC item represent?

Each STAC item includes several assets representing the individual data and metadata files associated with the scene. Items from different collections have different assets, as defined below and on our Product Details page.

vz-viri-l1a
Asset
Description
File Type

BLUE

Blue band digital number (DN) values

COG

GREEN

Green band DNs

COG

NIR

NIR band DNs

COG

RED

Red band DNs

COG

REDEDGE1

Red edge 1 band DNs

COG

REDEDGE2

Red edge 2 band DNs

COG

REDEDGE3

Red edge 3 band DNs

COG

QUALITY_ASSURANCE

Radiometric saturation mask

COG

PREVIEW

Full-resolution RGB preview image

COG

THUMBNAIL

Low-resolution RGB thumbnail

PNG

METADATA

Ancillary metadata file

JSON

COGs from the vz-viri-l1a collection are provided at the resolution of the VIRI sensor (~30 m).

vz-liri-l1a
Asset
Description
File Type

LWIR1

LWIR 1 band digital number (DN) values

COG

LWIR2

LWIR 2 band DNs

COG

QUALITY_ASSURANCE

Radiometric saturation mask

COG

PREVIEW_LWIR

Full-resolution LWIR preview image

COG

THUMBNAIL

Low-resolution thumbnail

PNG

METADATA

Ancillary metadata file

JSON

COGs from the vz-liri-l1a collection are provided at the resolution of the LIRI sensor (~70 m).

vz-l1b
Asset
Description
File Type

BLUE

Blue band digital number (DN) values

COG

GREEN

Green band DNs

COG

NIR

NIR band DNs

COG

RED

Red band DNs

COG

REDEDGE1

Red edge 1 band DNs

COG

REDEDGE2

Red edge 2 band DNs

COG

REDEDGE3

Red edge 3 band DNs

COG

LWIR1

LWIR 1 band DNs

COG

LWIR2

LWIR 2 band DNs

COG

QUALITY_ASSURANCE

Radiometric saturation mask

COG

CLOUD_MASK

Mask indicating cloud, cloud shadow, and snow or ice

COG

PREVIEW

Full-resolution RGB preview image

COG

PREVIEW_LWIR

Full-resolution LWIR preview image

COG

THUMBNAIL

Low-resolution RGB thumbnail

PNG

METADATA

Ancillary metadata file

JSON

COGs from the vz-l1b collection are provided at 30 m resolution.

vz-l2
Asset
Description
File Type

BLUE_SR

Blue band surface reflectance

COG

GREEN_SR

Green band surface reflectance

COG

NIR_SR

NIR band surface reflectance

COG

RED_SR

Red band surface reflectance

COG

REDEDGE1_SR

Red edge 1 band surface reflectance

COG

REDEDGE2_SR

Red edge 2 band surface reflectance

COG

REDEDGE3_SR

Red edge 3 band surface reflectance

COG

LWIR1_BT

LWIR 1 band brightness temperature

COG

LWIR2_BT

LWIR 2 band brightness temperature

COG

LWIR1_EMIS

LWIR 1 band emissivity

COG

LWIR2_EMIS

LWIR 2 band emissivity

COG

LST

Land surface temperature

COG

LST_UNCERTAINTY

Land surface temperature uncertainty

COG

QUALITY_ASSURANCE

Radiometric saturation mask

COG

CLOUD_MASK

Mask indicating cloud, cloud shadow, and snow or ice

COG

PREVIEW

Full-resolution RGB preview image

COG

PREVIEW_LST

Full-resolution LST preview image

COG

THUMBNAIL

Low-resolution RGB thumbnail

PNG

THUMBNAIL_LST

Low-resolution LST thumbnail

PNG

METADATA

Ancillary metadata file

JSON

COGs from the vz-l2 collection are provided at 30 m resolution.

I only see thumbnail assets for certain scenes. Where's the rest of the data?

You have full access to the scenes you've ordered and thumbnail access to the rest of the catalog.

What do the different values in the cloud mask mean?

The cloud mask encodes information about clouds, cloud shadows, and snow present within each pixel.

Specifically, the cloud mask contains bit-packed pixel values; each pixel value is a decimal representation of binary strings, in which each bit represents a different condition.

For simplicity, we recommend using the look-up table below. The table displays common pixel values and their meanings.

Value
No data
Cloud
Cloud shadow
Snow or ice
1
2
4
8

If you see a value of 2 in the cloud mask, for example, this would indicate cloudy conditions.

You can also review our how-to guide on using the cloud mask for additional information.

How can I use Hydrosat data with Google Earth Engine?

We recommend using the Google Earth Engine Python API along with the xee extension to smoothly integrate the two data sources.

I want to learn more about Hydrosat's data products. Where can I find more information?

You can find additional details in our product guide. Please reach out to your organization point of contact if you don't already have this document.

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