How Accurate Are Your Maps?

Short answer: with ground control, our maps are accurate to about a centimeter — roughly 25 to 50 times tighter than a handheld GPS. Here's what that means, how we prove it, and where the honest limits are.

Two different things people mean by 'accuracy'

It's worth separating two ideas that get mixed up:

1. Resolution (detail) — how much fine detail you can see. Our aerial maps are 1–3 cm per pixel, so a crack in a slab or a fence staple is visible. For comparison, satellite imagery is often ~50 cm per pixel — a completely different level of detail.
2. Positional accuracy (correctness) — how close a point's mapped position is to its true position on Earth. This is the 'about a centimeter' number, and it's what matters when you're measuring or handing data to an engineer.

How we get to centimeter accuracy: ground control

We don't just take the drone's word for where things are. For engineering-grade work we use ground control points (GCPs) — marker targets placed on the ground and recorded with centimeter-grade RTK GPS. They do two jobs:

1. Control points are fed into the processing to lock the whole map into its true position and scale.
2. Check points are deliberately held back from processing. After the map is built, we compare where the map places each check point against its known real position. The difference is an independent grade of the map's accuracy.

That check-point comparison produces an RMSE figure — think of it as the map's typical error, in centimeters. It's included in your Ground-Control Accuracy Report, so your accuracy isn't a marketing claim; it's a measured, documented number for your specific flight.

Without ground control

A flight flown without placed control still produces a beautiful, internally-consistent map — great for visuals, relative measurements, and getting the picture. Its absolute position on Earth just leans on the drone's onboard GPS, which is looser. If you need to defend a measurement, put it in a report, or align with civil design, choose a package with the ground-control accuracy option.

What affects the number in practice

• Ground control — the single biggest lever. Placed, precisely measured targets are what unlock centimeter-level positional accuracy.
• Tree and brush cover — a standard photo map measures the top of the canopy, not the ground. For accurate bare-earth terrain and volumes under cover, you need a LiDAR scan, which sees through gaps to the dirt.
• What you're measuring — crisp, well-defined features (a corner, a painted line, a marker) measure tighter than fuzzy ones (the exact edge of a bush).
• Vertical vs. horizontal — heights (vertical accuracy) are typically a bit looser than horizontal position. Your accuracy report states both.

What you can confidently do with the data

• Measure distances, areas, and acreage right in the browser viewer.
• Calculate stockpile and cut/fill volumes you can put in a report and defend.
• Plan grading, drainage, siting, and expansion off real elevation data.
• Hand georeferenced files to an engineer or GIS team that drop straight into their stack.

Tip: Want the tightest, most defensible numbers? Ask for the ground-control accuracy option when you scope the job, and leave the placed targets undisturbed until we've finished flying (see How to Prep Your Site).

The honest limit

Accurate as it is, this is mapping, not licensed land-surveying. Our data is engineering-grade for planning, measuring, and documentation — but it is not a legal survey. Embry Solutions LLC does not perform land surveys. For boundary, subdivision, or title surveys, please consult a licensed Texas surveyor. That line is on every deliverable on purpose — it protects you as much as us.