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Terrain
Elevation, slope, landform, erosion, visibility and the physical shape beneath every other layer.
Mission
Make local reality legible.
Public agencies collect extraordinary amounts of geographic information. Too often it remains trapped behind specialist interfaces, technical formats or maps that hide how the conclusion was made. Ground Truth Now exists to translate that evidence without stripping away its provenance.
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Water
Drainage, flood exposure, watersheds, surface water and how water actually moves through a place.
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Infrastructure
Roads, utilities, structures, access and the built systems layered over natural geography.
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Change
Imagery, climate records and historical comparisons that show what changed, where and when.
A map is not evidence because it looks precise. It becomes useful evidence when a reader can trace the data,
understand the processing and see where uncertainty begins.
Method
Source it. Map it. Test it. Publish it.
Every investigation follows the same basic chain so the result can be reproduced rather than merely trusted.
01 / SOURCE
Start with provenance.
Prefer primary government, scientific or locally authoritative geospatial sources. Record vintage, coverage and license.
02 / MAP
Build the spatial argument.
Align projections, inspect geometry, preserve raw data and perform only transformations that can be explained.
03 / TEST
Look for contradictions.
Compare independent layers, imagery and field observations. A clean narrative is not more important than conflicting evidence.
04 / PUBLISH
Show your work.
Publish the map beside its sources, methods, date and limitations so another person can inspect the conclusion.
Planned investigations
One place. One question. One inspectable map.
The first projects can stay deliberately small. Useful work does not require pretending to solve an entire region at once.
Hydrology
Where does the water actually go?
Combine elevation, mapped hydrography and flood information to explain drainage paths at neighborhood scale.
Terrain
What is the land doing here?
Use elevation and slope to make ridges, fans, channels, scarps and low points understandable to non-specialists.
Change
What changed between images?
Compare dated imagery and public records to document development, vegetation loss, disturbance or recovery.
Heat + climate
Why does this block feel hotter?
Compare land cover, shade, built form and climate observations without confusing correlation for causation.
Infrastructure
What does this system serve?
Map access, transportation or utility context to reveal how infrastructure relates to terrain and surrounding land use.
Field imagery
Can the map be checked on the ground?
In future projects, incorporate legally acquired field and aerial observations as additional evidence with date and location metadata.
Ground Truth evidence standard
Trust the chain, not the branding.
Every serious map published here should carry enough metadata for another GIS user to understand what happened between raw source and final image.
SOURCE + DATE + CRS + METHOD + LIMITATIONS = INSPECTABLE MAP
Name the source
Agency, dataset, service or field source with a direct reference whenever possible.
Record the vintage
Publication, acquisition or observation date matters. “Current” is not metadata.
State the spatial frame
CRS, resolution, relevant scale and any reprojection or resampling that affects interpretation.
Preserve raw inputs
Derived products should not quietly replace the original data used to create them.
Describe processing
Clips, joins, filters, interpolations, classifications and calculations belong in the record.
Publish uncertainty
Coverage gaps, positional accuracy, assumptions and conflicting datasets stay visible.
Primary source shelf
Start where the data comes from.
These are examples of foundational U.S. public geospatial sources suitable for future investigations. Each project should cite the exact dataset actually used.
U.S. Geological Survey — The National Map
National elevation, hydrography, structures, boundaries, transportation and other foundational geospatial data.
FEMA — National Flood Hazard Layer
Effective digital flood hazard information and related regulatory flood mapping products.
U.S. Census Bureau — TIGER/Line
Geographic boundaries and features that can be linked with Census demographic data.
NOAA/NCEI — Climate Data Online
Historical weather and climate observations including temperature, precipitation, wind and climate normals.
Ground Truth Now is an independent public-interest project and is not affiliated with USGS, FEMA, the U.S. Census Bureau or NOAA. Maps published by this project are explanatory products unless explicitly identified as an official agency product.