# Rasters

Raster data is composed of grids of pixels, where each pixel contains a value representing specific information, such as temperature, elevation, or vegetation indices. These datasets can represent continuous surfaces or sparse data with defined no-data regions. The CARTO platform provides seamless tools for importing, analyzing and visualizing raster sources directly in your data warehouse.

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## Visualizing rasters

To visualize raster sources, they must first be stored in your data warehouse using the **CARTO raster loader**. This tool ensures your raster files are properly uploaded and formatted for seamless integration with the CARTO platform. [Learn more about preparing and uploading your raster data](https://docs.carto.com/carto-user-manual/data-explorer/importing-data/importing-rasters).

To optimize performance, raster sources should include **overviews**—lower-resolution versions of the raster data—enabling efficient visualization at different zoom levels. Additionally, if your raster source contains a **color interpreter** (e.g., palette, grayscale, or RGB), CARTO will automatically apply default styling based on the metadata, making it easier to quickly render the raster on your map.

{% hint style="warning" %}
Note the current limitations and specific requirements for raster sources:

* Raster sources cannot be queried directly through SQL functions, meaning they are not compatible with **SQL Editor** or **SQL Parameters**. This is similar to the behavior of pre-generated tilesets.
* Raster sources are currently supported for **Google BigQuery, Snowflake and Databricks** environments.
  {% endhint %}