What is an orthomosaic map in drone surveying?

• Find out what an orthomasaic map is and how it differs from a standard aerial photo;

• Learn about flight planning to create an orthomosaic;

• How orthomosaics benefit a range of industries and how they differ from other drone survey outputs;

• Best DJI drones for creating orthomosaics;

• How heliguy™ survey department can help you start and scale your drone survey workflows.

An orthomosaic map is one of the most valuable outputs in drone surveying — especially for construction, infrastructure, and land projects.

Unlike a normal aerial photo, an orthomosaic is corrected for distortion, stitched together accurately, and scaled so you can measure real-world distances.

In this guide, we’ll explain what an orthomosaic map is, how drones create them, and when they’re the best deliverable for your workflow.

heliguy™ has an in-house survey department to help you start and scale your drone surveying workflows.

Key takeaways

• An orthomosaic is a stitched aerial map made from many photos that’s geometrically corrected and to scale.

• Orthomosaics are used for measurements, progress tracking, mapping, and reporting,

• Drones capture overlapping images, then photogrammetry software processes them into a single accurate map.

• Orthomosaics are often used alongside outputs like point clouds and 3D models.

• Orthomosaics outputs include RGB, thermal, and multispectral.

Expert insight

“Orthomosaics are one of the most client-friendly survey outputs — they’re easy to interpret but still powerful enough for measurements and project documentation.”

— Richard Dunlop, Head of heliguy™ Geospatial

Definition of an orthomosaic map

An orthomosaic is a high-resolution image map created by stitching together multiple overlapping aerial images into one corrected output.

Unlike a simple drone photo, an orthomosaic is processed so that the scale is consistent and the image can be used for mapping purposes.

The word 'ortho' refers to something being corrected or 'straightened', while 'mosaic' refers to many images being combined into one.

Orthomosaics are commonly used because they’re:

• Easy to understand visually.

• Simple to share with stakeholders.

• Valuable for measurement and planning.

How orthomosaics differ from standard aerial photos

A standard aerial photo looks good, but it usually contains distortion. This distortion happens because the camera captures a scene from a specific perspective, and objects closer to the camera can appear larger than objects further away.

Orthomosaics correct this distortion by:

• Aligning multiple images together.

• Modelling the surface geometry.

• Removing perspective 'warping'.

• Producing a consistent scale across the entire output.

This is why orthomosaics are more reliable for measurements than a single standalone drone image.

How drones create orthomosaic maps

Creating an orthomosaic map is a two-stage process: capture + processing. Good results depend on both steps being done correctly.

If either the capture is inconsistent (blur, low overlap) or the processing settings are wrong, the orthomosaic may contain distortions, misalignment, or gaps.

Flight planning and image capture

Orthomosaic capture normally involves flying a grid pattern over the target area with the camera facing straight down (nadir). The drone takes photos automatically at set intervals to ensure overlap.

Key capture considerations include:

• Stable altitude and flight path.

• Correct overlap settings.

• Consistent camera exposure.

• Suitable shutter speed to avoid blur.

• Calm weather conditions, where possible.

Even on small sites, professional planning matters — it improves the quality of the output and reduces processing failures.

Processing images in photogrammetry software

After the images are captured, photogrammetry software processes them into an orthomosaic. This involves aligning the photos, building a surface model, and stitching them into a corrected image.

Most processing workflows involve:

• Image alignment.

• Point cloud generation.

• Surface reconstruction.

• Orthomosaic output export.

The final orthomosaic can often be exported in formats suitable for mapping tools, reports, or GIS workflows.

Why orthomosaics matter for projects

Orthomosaics are valuable because they turn drone flights into decision-making tools. Instead of 'here’s a nice picture', you can say 'here’s a map you can measure and plan from'.

This is especially useful in industries where time, safety, and accuracy matter.

Measurement and analysis from orthomosaics

Orthomosaics can support measurements such as:

• Distance and area calculation.

• Site boundary checking.

• Progress comparison over time.

• Identifying layout changes.

• Quick checks for surface features.

While orthomosaics are not a replacement for every type of survey requirement, they provide a strong blend of accessibility and technical value.

Sharing orthomosaics with stakeholders

One reason orthomosaics are so popular is that they’re easy for non-specialists to interpret. A project manager can look at an orthomosaic and instantly understand what’s happening on a site.

Orthomosaics are commonly used for:

• Client reports.

• Planning meetings.

• Site coordination.

• Contractor communication.

• Evidence and documentation.

This makes them a practical deliverable even when stakeholders don’t have survey software expertise.

Drone orthomosaics vs other drone survey outputs

Orthomosaics are only one piece of drone survey data. Other outputs like point clouds and 3D models are often generated from the same dataset — but they support different types of analysis.

Choosing the right output depends on whether the priority is 2D mapping clarity or 3D geometric detail.

Orthomosaic vs point cloud

A point cloud is a 3D dataset containing millions of points that represent the shape of the surveyed area. Point clouds are powerful for engineering and modelling but are not always simple to interpret for general stakeholders.

Key difference:

• Orthomosaic: 2D map view, easy to share.

• Point cloud: 3D geometry dataset, more technical.

Many workflows use orthomosaics for visual reference and point clouds for deeper modelling tasks.

Orthomosaic vs 3D model

A 3D model is typically a textured mesh output that shows surfaces and structures in realistic detail. It can be valuable for visualisation and understanding complex shapes.

Key difference:

• Orthomosaic: Best for plan-view measurement.

• 3D model: Best for height/structure visualisation.

If your client needs “a map we can measure”, orthomosaic is often the best output. If they need “a model we can inspect from all angles”, a 3D model may be the better choice.

What types of orthomosaic maps can you create?

The above images show standard RGB orthomosaics, but drone 2D maps aren't limited to visual imagery.

Other orthomosaic outputs include thermal (pictured below) and multispectral. While LiDAR doesn’t create a traditional photo-based orthomosaic, LiDAR surveys can produce intensity or reflectance maps that behave similarly to orthomosaics.

The type of orthomosaic depends on the sensor your drone has.

Orthomosaic drone survey outputs by sector

This table shows how drone orthomosaic mapping can benefit a range of applications.

*LiDAR does not create a traditional image-based orthomosaic, but LiDAR surveys often generate intensity or elevation maps that are used alongside RGB orthomosaics in professional drone surveying workflows.

Best drones for orthomosaics

The best DJI drones for orthomosaics include:

Software and tools for orthomosaic generation

Orthomosaics require photogrammetry processing tools. While drones can automate the flight, the processing stage is where the final output is created and quality is determined.

Selecting the right software depends on your required deliverables, output formats, and workflow complexity.

For DJI drones, DJI Terra offers a DJI ecosystem solution, designed for rapid 2D orthomosaic generation.

This includes Gaussian Splatting functionality to generate distortion-free orthomosaics, further improving the quality of the results.

Working with heliguy™ survey specialists

If you want orthomosaic outputs without workflow guesswork, heliguy™ can help you, with survey specialists who understand capture planning, processing standards, and deliverable expectations.

Our in-house survey team offers drone and software consultancy and supply, dedicated survey training, data processing advice and assistance, and on-going survey support.

Orthomosaic maps: Summary

Orthomosaics are one of the most practical drone survey deliverables because they combine accessibility with real mapping value. They’re easy to share, easy to interpret, and useful for measurements, progress tracking, and reporting.

If your project needs a clear 2D overview that supports planning and decision-making, an orthomosaic map is often the ideal choice.