Build a topography grid from 3DEP

Fire spreads uphill, and slope and aspect drive that. This guide builds a topography grid — elevation, slope, and aspect — for your domain from the USGS 3DEP elevation program.

Prerequisites

1. An API key: my-api-key.

2. A domain within CONUS: your-domain-id. See Create a domain.

Step 1 (optional) — Check 3DEP coverage

3DEP publishes seamless 10 m and 30 m DEMs nationwide, plus 1 m lidar where it’s been flown. Before requesting high-resolution data, check what’s available over your domain:

curl

GET topography/3dep/coverage

curl -X 'GET' \
  'https://api-v2-prod-nyvjyh5ywa-uw.a.run.app/domains/your-domain-id/grids/topography/3dep/coverage' \
  -H 'accept: application/json' \
  -H 'api-key: my-api-key'

Response

{
  "resolution": 1,
  "available": false,
  "tile_count": 0,
  "tiles": [],
  "acquisition_dates": null
}

Here available: false means no 1 m lidar tiles intersect this domain — so fall back to the seamless 10 m DEM (the default). When 1 m lidar is available, tiles and acquisition_dates list what would be used.

Step 2 — Create the topography grid

source_resolution picks the 3DEP product to sample (10 for the seamless 10 m DEM; 1 only where the coverage check reports it). bands selects which surfaces to compute — slope and aspect are derived from the elevation surface.

curl

POST topography/3dep

curl -X 'POST' \
  'https://api-v2-prod-nyvjyh5ywa-uw.a.run.app/domains/your-domain-id/grids/topography/3dep' \
  -H 'accept: application/json' \
  -H 'api-key: my-api-key' \
  -H 'Content-Type: application/json' \
  -d '{
  "name": "Topography (3DEP 10 m)",
  "source_resolution": 10,
  "bands": ["elevation", "slope", "aspect"]
}'

Response

{
  "id": "your-grid-id",
  "domain_id": "your-domain-id",
  "name": "Topography (3DEP 10 m)",
  "description": "",
  "status": "pending",
  "progress": null,
  "created_on": "2026-05-25T18:47:45.060982",
  "modified_on": "2026-05-25T18:47:45.060982",
  "source": {
    "name": "3dep",
    "product": "topography",
    "source_resolution": 10,
    "description": "3DEP topographic data (elevation, slope, aspect)",
    "extent_buffer_cells": 0,
    "alignment": {
      "target": "domain",
      "resolution": null,
      "method": null
    },
    "bands": ["elevation", "slope", "aspect"],
    "tile_metadata": null
  },
  "modifications": [],
  "bands": [
    {
      "key": "elevation",
      "type": "continuous",
      "unit": "m",
      "index": 0
    },
    {
      "key": "slope",
      "type": "continuous",
      "unit": "deg",
      "index": 1
    },
    {
      "key": "aspect",
      "type": "continuous",
      "unit": "deg",
      "index": 2
    }
  ],
  "georeference": null,
  "error": null,
  "chunks": {
    "shape": [512, 512],
    "count": null,
    "count_by_axis": null
  },
  "tags": []
}

Record the grid id: your-grid-id.

Step 3 — Poll until completed

poll

GET grid status

curl -X 'GET' \
  'https://api-v2-prod-nyvjyh5ywa-uw.a.run.app/domains/your-domain-id/grids/your-grid-id' \
  -H 'accept: application/json' \
  -H 'api-key: my-api-key'

completed

{
  "id": "your-grid-id",
  "domain_id": "your-domain-id",
  "name": "Topography (3DEP 10 m)",
  "description": "",
  "status": "completed",
  "progress": {
    "percent": 100,
    "message": "Complete"
  },
  "created_on": "2026-05-25T18:47:45.060982Z",
  "modified_on": "2026-05-25T18:47:48.430060Z",
  "source": {
    "name": "3dep",
    "bands": ["elevation", "slope", "aspect"],
    "description": "3DEP topographic data (elevation, slope, aspect)",
    "alignment": {
      "target": "domain",
      "method": null,
      "resolution": null
    },
    "extent_buffer_cells": 0,
    "source_resolution": 10,
    "tile_metadata": {
      "tile_count": 1,
      "acquisition_dates": null,
      "tile_source": null,
      "native_crs": "EPSG:4326",
      "tiles": [
        "https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/13/TIFF/current/n47w115/USGS_13_n47w115.tif"
      ]
    },
    "product": "topography"
  },
  "modifications": [],
  "bands": [
    {
      "key": "elevation",
      "type": "continuous",
      "unit": "m",
      "index": 0
    },
    {
      "key": "slope",
      "type": "continuous",
      "unit": "deg",
      "index": 1
    },
    {
      "key": "aspect",
      "type": "continuous",
      "unit": "deg",
      "index": 2
    }
  ],
  "georeference": {
    "crs": "EPSG:32611",
    "transform": [
      7.7301175133338464, 0.0, 720227.9398802927, 0.0, -7.730117513336364,
      5190652.2875135
    ],
    "shape": [115, 169]
  },
  "error": null,
  "chunks": {
    "shape": [512, 512],
    "count": 1,
    "count_by_axis": {
      "x": 1,
      "y": 1
    }
  },
  "tags": []
}

The three bands come back with units m (elevation) and deg (slope, aspect). On the Blue Mountain domain elevation runs ≈957–1170 m up the valley flank — real sampled terrain, not a placeholder.

Tip

Need it at your fuel grid’s resolution? 3DEP is sampled at source_resolution, then aligned to the domain. To match an existing grid exactly (cell size and origin), build the topo grid, then resample it onto the target grid.

Common pitfalls

• Requesting source_resolution: 1 where lidar isn’t flown. The coverage check (step 1) tells you up front — if available is false, use 10.
• Domain outside CONUS. 3DEP is a US program; domains elsewhere have no coverage.
• Expecting slope/aspect without elevation. They’re derived from the elevation surface; the service computes them from the sampled DEM, so just list the bands you want.