# SAM - UFRGS ANADEM 30m

> ANADEM: a bare-earth Digital Terrain Model for South America at ~30 m resolution, produced by the Federal University of Rio Grande do Sul (UFRGS/IPH) with the…

- **Collection ID:** `sam-ufrgs-anadem-30m`
- **Resolution:** 30 m
- **Products:** Digital Terrain Model
- **Coverage:** 82.5°W to 31.9°W, 56.8°S to 14.1°N
- **Time range:** 2011 – 2015
- **Items indexed:** 1
- **License:** [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)
- **STAC JSON:** https://api.darly.io/collections/sam-ufrgs-anadem-30m

ANADEM: a **bare-earth Digital Terrain Model for South America** at ~30 m resolution, produced by the Federal University of Rio Grande do Sul (UFRGS/IPH) with the Brazilian National Water and Sanitation Agency (ANA).

**Source & method:** A true **Digital Terrain Model (DTM)** — it removes the vegetation bias from the Copernicus DEM GLO-30 surface model with a machine- learning correction calibrated specifically for South America, combining Landsat-8 / Sentinel-2 spectral indices (EVI, NDMI, MSAVI) with GEDI spaceborne- lidar ground elevations.

**Resolution:** 30 m nominal, on a single continent-wide mosaic (one item, not tiled).

**Coordinate reference:** Geographic SIRGAS 2000 (EPSG:4674 — WGS84-equivalent at this resolution); elevations in meters on the EGM2008 geoid (EPSG:3855).

**Hosting:** The asset references the public, anonymously readable Cloud-Optimized GeoTIFF on OpenTopography (`opentopography.s3.sdsc.edu`) **in place** — Darly does not re-host or copy the pixels.

**Coverage:** Continental South America (82.5°W–31.9°W, 56.8°S–14.1°N).

**Version:** v1 (current). New non-breaking versions overwrite this mosaic in place; a breaking change (different resolution/CRS/datum) would get its own collection.

**Documentation:**
- [ANADEM project page](https://hge-iph.github.io/anadem/)
- [OpenTopography dataset](https://portal.opentopography.org/raster?opentopoID=OTSDEM.082025.4674.1)
- [Remote Sensing paper (DOI 10.3390/rs16132321)](https://doi.org/10.3390/rs16132321)

## Providers

- [Universidade Federal do Rio Grande do Sul (UFRGS/IPH)](https://hge-iph.github.io/anadem/) (producer, processor, licensor)
- [Agência Nacional de Águas e Saneamento Básico (ANA)](https://www.gov.br/ana/) (producer)
- [OpenTopography](https://portal.opentopography.org/raster?opentopoID=OTSDEM.082025.4674.1) (host)
- [Darly](https://darly.io) (processor)

## Citation

Laipelt, L.; Andrade, B.C.; Collischonn, W.; Teixeira, A.A.; Paiva, R.C.D.; Ruhoff, A. (2024). ANADEM: A Digital Terrain Model for South America. Remote Sensing, 16(13), 2321.

## Access

```bash
curl "https://api.darly.io/collections/sam-ufrgs-anadem-30m/items?limit=5"
```

Browse it in the [Data Explorer](https://darly.io/explorer) or read the [STAC API docs](https://darly.io/docs/stac).