Community characteristics
Three layers count buildings, housing units, and people on a 30 m grid. They come from the USDA Forest Service's Wildfire Risk to Communities program (Populated Areas publication, RDS-2020-0060-2), derived from building footprints overlaid with U.S. Census records. Buildings are counted from footprints above a 40 m² (430 ft²) minimum on habitable land — no water or permanent ice/snow. AOI sums are the meaningful number; a single 30 m pixel value is an estimate, not a head-count.
How WyldFire processes every layer
Each WRC raster is clipped to the USGS Wyoming state boundary plus a
24-km buffer for edge tolerance on AOIs that straddle
the state line, scaled to compact integer storage using a documented
scaleFactor where appropriate, and re-encoded as a Cloud
Optimized GeoTIFF on S3, addressable via /vsicurl/ HTTP
range reads. The viewer multiplies by scaleFactor when
rendering and reporting; direct COG readers must apply it themselves.
Layers at a glance
| Layer | What it measures | Native res | scaleFactor | Years |
|---|---|---|---|---|
bc |
Building count | 30 m | 1.0 |
2020 |
hu |
Housing unit count | 30 m | 0.1 |
2020 |
pc |
Population count | 30 m | 0.01 |
2020 |
Building count bc
What it is
"The approximate number of buildings within a 30-meter pixel. No spatial smoothing is applied to this layer."
Whole-number counts. Only buildings with footprints larger than the WRC minimum of 40 m² (≈430 ft²) are included, and only those falling on habitable ground (open water and permanent ice/snow excluded).
How upstream computes it
WRC starts from a CONUS building-footprint dataset and assigns each footprint centroid to its containing 30 m pixel. The pixel value is a count of the number of qualifying footprint centroids that fall inside it.
How WyldFire processed it
Clipped to Wyoming + 24-km buffer. No scaling
(scaleFactor = 1.0) because buildings are genuinely
countable objects — fractional values would have no physical
meaning. Re-encoded as a COG on S3.
Storage vs display
Native integer counts. Viewer renders with a class-breaks color ramp (the bins are a viewer convention for legibility, not part of the raster).
30 m semantics
A pixel of 3 means three qualifying footprints had
their centroid in that 30 m × 30 m square (≈0.22 acres). Aggregate
across an AOI for the headline number; individual pixels are useful
for finding clusters but should not be read as building inventories.
Caveats
"The datasets presented here are the product of modeling, and as such carry an inherent degree of error and uncertainty. These datasets are intended to provide nationally-consistent information for the purpose of comparing relative wildfire risk among communities nationally or within a state or county. Data included here are not intended to replace locally-calibrated state, regional, or local risk assessments where they exist."
Outbuildings under 40 m² are excluded. Footprint completeness varies by region. Not for parcel-level analysis.
Year availability
2020.
Provider & citation
USDA FS WRC, RDS-2020-0060-2. Jaffe, Melissa R.; Scott, Joe H.; et al. Wildfire Risk to Communities: Spatial datasets of wildfire risk for populated areas in the United States. Fort Collins, CO: Forest Service Research Data Archive. doi.org/10.2737/RDS-2020-0060-2
Housing unit count hu
What it is
"Housing is defined as buildings that are likely to have occupants, according to building footprints and 2021 U.S. Census Bureau datasets. … The approximate number of housing units in each 30-meter pixel."
A subset of bc restricted to the buildings most likely
to contain occupants, then Census housing-unit counts are allocated
across those qualifying footprints.
How upstream computes it
Census-block housing-unit counts (2021 American Community Survey vintage) are distributed onto the WRC building footprints judged habitable, then aggregated to 30 m pixels. The allocation step is why per-pixel values are not whole numbers — Census counts are block-level, and dividing them across multiple footprints in the same block produces fractional pixel values.
How WyldFire processed it
Clipped to Wyoming + 24-km buffer. Scaled by
scaleFactor = 0.1 so the Census-allocation values
(typically 0 to ~10 per pixel, often fractional) compress to small
integers in storage. Re-encoded as a COG on S3.
Storage vs display
Multiply raw integer pixel values by 0.1 to recover
housing-unit counts. Viewer renders with a class-breaks color ramp.
30 m semantics
A pixel of 0.7 hu does not mean "0.7
households live here." It reflects the Census allocation step —
a fractional share of a block's housing-unit total has been
attributed to this pixel. Sum across the AOI for the headline
number; never read a single pixel as a household count.
Caveats
Subject to the same WRC use-limitations quoted in the bc
section. Allocation uncertainty is highest where blocks are large
relative to the building footprint density. Census vintage is 2021;
anything built more recently is missing.
Year availability
2020.
Provider & citation
USDA FS WRC, RDS-2020-0060-2. doi.org/10.2737/RDS-2020-0060-2
Population count pc
What it is
"The approximate number of people living in each 30-meter pixel. No spatial smoothing is applied to this layer."
How upstream computes it
Census-block population counts are allocated onto the same
habitable-footprint set used for hu, then aggregated to
the 30 m grid. Same general allocation approach as hu,
with the population numerator substituted for the housing-unit
numerator.
How WyldFire processed it
Clipped to Wyoming + 24-km buffer; scaled by
scaleFactor = 0.01 (population values per 30 m pixel
run higher than housing-unit values, so a finer scale is used);
re-encoded as a COG on S3.
Storage vs display
Multiply raw integer pixel values by 0.01 to recover
person counts. Viewer renders with a class-breaks color ramp.
30 m semantics
A pixel of 2.4 pc means an estimated 2.4 people are
attributed to this 30 m square through the Census-allocation step.
Aggregate across the AOI for population sums; per-pixel values are
estimates, not headcounts.
Caveats
Same WRC use-limitations quoted in the bc section.
Allocation uncertainty applies; transient population (workplaces,
tourism, seasonal residences) is not separated from residential
population.
Year availability
2020.
Provider & citation
USDA FS WRC, RDS-2020-0060-2. doi.org/10.2737/RDS-2020-0060-2