Orthomosaic Mapping Explained

An aerial photo shows you what a site looks like. An orthomosaic shows you where things are. That difference is the entire reason this deliverable exists, and it is the thing most people are unclear on when they ask for "drone pictures of the site."

What an orthomosaic actually is

A single photo taken from a drone has perspective distortion built into it. Objects directly below the camera look correct. Objects toward the edges of the frame lean outward, because you are seeing them slightly from the side. Distances measured across that photo are wrong, and they are wrong by different amounts in different parts of the image.

An orthomosaic is built differently. The drone flies a grid and takes hundreds of overlapping photos. Software matches common points between the overlapping frames, works out the three-dimensional shape of the ground, and then re-projects every pixel as though the camera were directly above it. The result is stitched into one continuous image.

The practical effect is that the finished map has a consistent scale across its whole surface. A hundred feet in one corner is the same number of pixels as a hundred feet in the opposite corner. That is what makes it something you can measure on and overlay, rather than something you can only look at.

The file is georeferenced, meaning every pixel carries a real-world coordinate. Dropped into CAD or GIS, it lands in the correct place and at the correct scale without anyone stretching it to fit.

What you receive

A mapping flight produces several things, and which ones matter depends on who is using them.

A note on the surface model, because it is a common source of disappointment. What photogrammetry produces is a model of the surface — the top of whatever the camera can see. Tree canopy, parked vehicles, and stockpile covers are all part of that surface. It is not a bare-earth model of the ground beneath them. If your project needs ground elevation under vegetation, that is a LiDAR job, and we will tell you so rather than sell you something that will not answer the question.

When an orthomosaic is worth paying for

The map earns its cost when someone is going to do something with it beyond looking.

• Monthly construction progress. Flown from the same waypoints each visit, the maps stack cleanly and month three lines up with month one. Owners and lenders can see the sequence rather than a folder of loose photos.
• Earthwork and stockpile quantities. Volume calculated from the captured surface, repeated over time, gives a defensible record of material movement.
• Existing-conditions capture. Before design starts, a current picture of what is actually on the site, rather than a plan drawing from two years ago.
• Land planning and due diligence. Parcel context, access, drainage patterns, and adjacent development, all in one measurable image.

When it is not

Plenty of jobs are better served by ordinary aerial photography, and it costs less.

If the output is going into a brochure, a listing, a board presentation, or a website, you want photographs. Nobody looking at a marketing page is measuring anything, and a well-composed oblique shot from four hundred feet communicates a site far better than a flat overhead map does. See aerial photography for real estate if that is closer to what you need.

Small sites are also a poor fit. The fixed costs of a mapping flight — planning, travel, processing — do not shrink much for a quarter-acre lot, so the price per acre gets steep.

How the flight is planned

Three things determine whether the finished map is usable, and all three are decided before anyone arrives.

Overlap. The software needs to see the same ground feature in many photos to reconstruct it. Flights are planned with heavy overlap front and side. Gaps in overlap become holes or distortion in the finished map, and they cannot be patched afterward without re-flying.

Altitude. Higher covers more ground per battery but resolves less detail. Lower resolves more but takes longer and produces far more images to process. The altitude is set by what the map has to show, which is why the first question is always what the deliverable feeds into.

Georeferencing. Position data is corrected in flight against a network reference, so images carry accurate coordinates as they are captured rather than being fitted to the ground afterward.

What degrades a map

Worth knowing before you schedule, because some of these are avoidable.

• Wind pushes the aircraft off the planned line and introduces motion blur. Beyond a certain point the flight is postponed.
• Harsh midday sun produces hard shadows that hide detail and confuse the matching software. Overcast is often better for mapping than a bright clear day.
• Moving vehicles and equipment appear in some frames and not others, and end up smeared or duplicated. A site that can pause traffic during the flight produces a cleaner map.
• Water, glass, and large blank surfaces have no texture for the software to match. These areas reconstruct poorly, and we flag them in the delivery rather than quietly smoothing them over.
• Dense vegetation hides the ground, as covered above.

What to send when you request one

The more of this you can provide up front, the faster the quote and the less chance of a surprise.

1. The site address, or a boundary file if you have one
2. What the map feeds into — CAD, GIS, an owner report, a volume calculation
3. The coordinate system your team works in, if the file is going into an existing project
4. Any access constraints, active operations, or nearby airports you already know about
5. Whether this is a one-time capture or a recurring schedule

Recurring work is quoted differently from one-off flights, and meaningfully lower per visit. Scope is on the mapping service page and published starting prices are on the pricing page.

Frequently asked questions

How large an area can be mapped in one day?

A single flight day covers a substantial site. The limiting factors are battery cycles, the altitude the deliverable requires, and how much of the day has usable light. Very large parcels are flown across multiple days and merged.

Can the map be delivered in our coordinate system?

Yes. Files come out in UTM by default. Tell us the coordinate reference system and vertical datum your team uses and the deliverable is reprojected before handoff.

Is this the same as a land survey?

No. A licensed land surveyor produces a survey of record, establishes boundaries, and stamps the result. This is a measured aerial capture that supports planning, documentation, and quantity work. The two are often used together, and on projects where a legal boundary matters, the surveyor's work governs.

How long does processing take?

Photogrammetric processing takes substantially longer than the flight itself. Expect delivery several business days after the capture, with larger sites at the longer end.

Can you fly a site next to an airport?

Usually. Most of the Los Angeles basin can be cleared for flight, often the same day. Sites close enough to an airport to need a longer approval exist, and we identify those when you send the address rather than on the morning of the flight. See where we work.