Orthomosaic aerial photo of small island

What Is Orthomosaic Map?

Estimated reading time: 7 minutes

Also known as an orthophotograph or orthoimage, an orthomosaic map is a geometrically corrected aerial image free of perspective errors and distortions. Creating orthoimages begins with capturing images. These images are then translated into sharp Google map-like quality images. 

Unlike Google Maps, you can zoom in and out of Orthomosaic Maps without distortions.  

Orthomosaic maps reflect the actual features of a terrain, providing even the tiniest details. 

This provides a detailed top-down view of an area, helping constructors, emergency service providers, agriculturalists, realtors, and other professionals make sound project decisions and efficiently manage their projects. 

Keep reading to learn more about Orthomosaic maps, how to make Orthomosaic Maps, their uses, and more!

Let’s dive right in.

What Is Orthomosaic Map?

Orthomosaic maps are geometrically corrected aerial images, free of distortions. They provide precise geolocation and uniform scale, contrary to what traditional aerial photographs provide. 

Orthoimages are translated into sharp Google map-like, high-quality, and accurate images. 

They reflect the real features of terrains, providing information to the tiniest details. Hence, they’re essential for professionals who want to analyze, plan, and decide on their projects. 

The orthomosaic map is in GeoTIFF format, which is commonly used in remote sensing applications and GIS (Geographic Information Systems). The format stores georeferenced raster images, which are commonly used for spatial analysis and mapping. 

Image Credits

How to Make Orthomosaic Maps?

There are three main steps involved in creating Orthomosaic Maps:

  • Flight planning: Determine the flight path, image overlap, and altitude to ensure the targeted area is comprehensively covered. 
  • Image capturing: Drones featuring high-resolution cameras help capture several overlapping photos using a drone or an AUV. 
  • Data processing: Generating the final orthoimages involves importing the captured images into special photogrammetry software like Agisoft, DroneDeploy, or Pix4D. These images are then ‘stitched together’ and all distortions corrected for sharp, high-quality orthoimages. This software is also responsible for aligning images based on GPS coordinates. For uniformity across the map, the photogrammetry software also adjusts the scale. The results? An accurate, well-detailed Orthomosaic Map.

What Are the Common Uses of Orthomosaic Maps?

Some of the most common uses of Orthomosaic maps include agriculture, archaeology, land management, conservation, building and construction, and infrastructure inspection.

Let’s have each of these uses under our microscope for a better understanding. 

Agriculture:

Farmers use Orthomosaic maps to assess and evaluate the growth and health of their plants, and then make well-thought-out decisions to increase their yields. 

Orthomosaic maps help farmers identify inadequately irrigated areas and parts of their crops infested by diseases and pests. 

Archaeology:

Orthomosaic maps enable archaeologists to analyze and document archaeological sites. This is essential in preserving historical information and viewing the excavated areas for better planning and project analysis. 

Aerial panoramic spring view of the ruined Ancient
Aerial panoramic spring view of the ruined Ancient

Management of land:

Land managers can oversee, allocate natural spaces of private or public projects, and conserve land effectively and efficiently after monitoring and analyzing updated aerial imagery of their land. 

Monitoring Environmental Changes:

The government can use Orthomosaics maps to monitor deforestation, poaching, soil erosion, and floods, among other threats to animals and humanity, and take the necessary measures to conserve the environment and save lives.  

Building and construction:

Orthophotographs are free of distortions, making them excellent for providing error-free volumes, distances, and areas during construction. 

Inspection of Infrastructure:

Orthophotographs help inspect bridges, structures, roads, and other infrastructure to effectively and successfully plan repairs and maintenance of faulty structures.

What Are the Benefits of Using Drones in Orthomosaic Mapping?

Orthomosaic mapping has various key benefits, including efficiency and safety, affordability, ease of use, better data collection, and precision and accuracy, among others.

Let’s take a closer look at each of these benefits below.

Affordability:

Using drones for Orthomosaic mapping instead of ground-based surveys or manned aircraft is far cheaper than other tools, especially if surveying large hectares of land. 

Drones quickly survey many hectares of land, lowering the overall cost. 

Efficiency and Safety:

Drones replace people in hazardous working environments. Their ability to access high-risk and hard-to-access areas such as dense forests, flooded areas, and construction sites, among others, saves lives by eliminating the need to hire people whose lives could be highly endangered.  

Ease of Use:

Anyone trained as an Orthomosaic drone operator can easily operate and execute the job without any struggles. Besides, orthomosaic drones have user-friendly interfaces that make them easy to use and operate. 

The automated flight software enables Orthomosaic drone pilots to execute all tasks easily and effortlessly without much drone operation training. 

The versatility of Orthomosaic drones makes them usable in various applications, including agriculture, construction, and research. 

Precision and Accuracy:

Orthomosaic drones provide error-free maps, making them the best choice for professional projects. Due to technological advancements, these drones have GPS and sensors and offer centimeter-level accuracy when taking aerial images. 

This is vital in certain industries, especially building and construction.

Orthomosaic drones capture high-resolution, well-detailed images essential for collecting data, analyzing, and making decisions. These images can be processed to create topographic maps, among other things.

Real-Time Data Collection:

Like other drones, orthomosaic drones have infrared cameras, thermal sensors, video cameras, and LiDAR (Light Detection and Ranging) technology. 

This technology helps them collect vital data in real-time, making it easy to make prompt decisions and take swift actions, especially during emergencies. 

Environmental Impact:

Compared to manned aircraft, drones produce minimal emissions, lowering their environmental impacts. 

How to Make an Orthomosaic Map With a Drone?

If you want to create top-notch, high-quality orthophotos, here are a few steps. 

  • Pre-plan: Before taking any flight, you must pre-plan the drone’s speed, flight path, the overlap needed between images, and altitude. Using specialized software helps identify the best flight parameters for full coverage of an area. Make sure that the weather is drone-friendly before any flight. 

Avoid flying in low visibility, strong wind, or rainy conditions, as these could damage your drone or cause it to fly away. Charge the battery before the flight and ensure the spare batteries are fully charged. Inspect your drone for damage to the motor, battery, and propeller. 

  • Capture images: Position yourself in an open, safe location and launch your drone. Drones have precise GPS systems and high-resolution cameras that enable them to capture well-detailed and accurate images. However, they follow a predetermined path to capture photos. 
  • Process Post-Flight Data: Use your computer to transfer your images to the drone’s memory. To Georeference your images, assign each one GPS coordinates and then process the images using specialized photogrammetry software. 

The software identifies specific features and creates a 3D point cloud to generate the initial map. To rectify distortions caused by the angle of the drone during flights and the terrain, orthorectify the map for accuracy. 

  • Generate and analyze the map: Use the photogrammetry software to stitch together the captured images for an accurate, coherent orthomosaic map. 
  • Inspect the quality: Inspect your images and ensure they’re accurate and well-detailed.   
Photogrammetry software to stitch images

Image Credit

Factors to Consider When Selecting an Orthomosaic Drone:

If you’re looking for an Orthomosaic Drone, here are a few factors to consider:

  • IP Rating considerations: Based on where you live and the weather conditions, check the drone’s IP rating and buy a drone that can withstand varying weather conditions. 
  • Camera resolution: If you want detailed images, buy a drone whose camera offers a resolution of 20 megapixels or more.
  • Battery life: Drones with a flight of 30 minutes and above are better, especially if you want to take many images.
  • Compatibility: Your drone must be compatible with the photogrammetry software to process data and create Orthomosaic maps.
  • GPS accuracy: Drones with PPK (Post-Processing Kinematic) or RTK (Real-Time Kinematic) technology are excellent for ensuring accuracy. 

Parting Shot:

Since Orthomosaic Maps provide accurate data, most industries, including agriculture, building and construction, and search and rescue, depend on them for key information. Besides, they’re cheap, versatile, efficient, and safe.  

Project managers can make well-informed decisions based on the collected information. Remember to follow the key steps for an accurate capture: flight planning, image capturing, and data processing.

HAPPY FLYING!

Summary
Article Name
What Is Orthomosaic Maps?
Description
Keep reading to learn more about Orthomosaic maps, how to make Orthomosaic Maps, their uses, and more!
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Remoteflyer Private Limited
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