How do I order an Orthomosaic?

The orthomosaic results from a photogrammetric survey with drones and a deliverable that allows us to appreciate the context of a specific area more clearly.

How works capture an Orthomosaic map?

An orthomosaic map is an aerial photo of an earth's surface. An orthomosaic map is an aerial photo of an earth's surface an aerial photograph captured in support of drone mapping software. Creating orthomosaic maps with the captured image collection can help in construction projects or construction sites.

To generate an orthomosaic image is necessary to use a camera with the appropriate specifications; the camera tilt will depend on the topographic relief. In addition, another common error that can occur is that lens distortion generates images that need to be fixed or are properly geometrically corrected.

Construction orthomosaic maps

An orthomosaic is a photogrammetrically orthorectified image product mosaicked from an image collection. The geometric distortion has been corrected, and the imagery has been color balanced to produce a seamless mosaic dataset.

To correctly build and generate an orthomosaic, the construction site or project must be established.

The information above orthomosaic maps

To request an Orthomosaic service, you must consider the following factors:

Resolution

This concept refers to the number of centimeters per pixel or cm/px and is indirectly proportional to the resolution of the final image; that is, the lower the number of centimeters per pixel, the higher the resolution of the photograph or orthomosaic.

The increase in resolution is directly proportional to the weight of the files, which sometimes, if computers are not robust enough, can impede viewing or working with them in other software.

Georeferencing

Drones by themselves have a geo-positioning system that helps them to locate themselves in space when they are mapping through a previously defined route; that positioning is metric grade, that is, its absolute precision is greater than 50 cm, but with With the help of a correct ground control carried out with sub-meter positioning systems, absolute errors of less than 10 cm can be achieved in combination with the requested resolution.

Currently, RTK real-time positioning systems help us make the initial product from the original photographs more accurate than with the original drone positioning system. Still, to achieve greater precision, you must confirm with geo targets located on the ground.

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Deliverable format

As the orthomosaic is a raster or image, it has different ways of being delivered, and it is important to note that the orthomosaics can be delivered as one or in parts:

• All in one big orthomosaic (usually in .tiff or .jpg)

Advantages

• It is a single file.
• Easy to browse by having a single image open.
• It can be reduced in size by sacrificing resolution.

Disadvantages

• It can be very heavy.
• Not all computers can open it.
• Slower to download.

Divided into tiles or tiles, that is, generating the orthomosaic in equal divisions

Advantages

• Much lighter.
• You can turn it on or off, whatever you want.
• Ideal for importing into AutoCAD.
• Faster to download.

Disadvantages

• Each tile must be accessed to review it, which hurts the experience of visualizing the full context of the area.
• Many files are generated.

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In high resolution

Advantages

• Details are much better appreciated.
• Represents the resolution for which the flight was made.

Disadvantages

• Weight can increase a lot
• Difficult to download
• More robust equipment is required to visualize

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In low resolution

Advantages

• Very manipulable
• No robust equipment required
• Easy to share

Disadvantages

• The resolution for which the work was done was lowered
• This prevents details from being reviewed in depth

In Google Earth, we recommend this version since no special software or licenses are required. GE is a very intuitive program that almost everyone knows how to use as a reference tool.

Advantages

• No licenses required
• Very intuitive
• Can be shared in high or low resolution
• You can rely on the satellite context
• Layers can be turned on at different times to visualize the changes between them quickly.

Disadvantages

• When sending high-resolution images, the files are heavy
• Do not sync

It is important to mention that in addition to the context provided by the Orthomosaic, it is widely used for vectorization work such as planimetry, that is to say, making a plane in AutoCAD from tracing the limits of objects, properties or infrastructure that are seen in it in the same way It is a useful tool for cadastre work.

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