TRUE ORTHOPHOTO / true ortho imagery

True orthophotos give a vertical view of the earth's surface, eliminating building tilting and allowing a view of nearly any point on the ground.

Comparison orthophoto and true orthophoto: in the right picture the roof of the building is directly above its ground plan.

True orthophoto services at a glance

• rectified and true to scale image without object tilting
• flying with increased image coverage (80%/60%)
• no blind spots
• four channel image (RGB + infrared)
• derivation of surface models

True Orthophotos in detail

The true orthophoto is created on the basis of pixel-sharp surface models in a fully automated process.

The benefit of the true orthophoto compared to a classic orthophoto is that objects outstands from the terrain, such as buildings, are not displayed tilted in the image. This avoids the creation of obscured parts.
The basis for the creation of a true orthophoto is the aerial survey with increased overlap of images. For an orthophoto, an overlap of 60 percent in the flight direction and 30 percent across the flight direction is sufficient. For a true orthophoto, these overlaps must be doubled to at least 80 percent in the flight direction and 60 percent across the flight direction.
The orientation data for the stereo models are calculated with the use of high-precision aerotriangulation. Based on this orientation data, elevation points are derived from the aerial survey data using the semi-global matching algorithm. The result of this process is a terrain model. For well defined points such as roads or roofs, the height accuracy of the individual points is less than 10 cm.
Due to the geometric accuracy of the true orthophoto, the benefit in technical surveying is much better than using normal orthophotos. For the processing of true orthophotos and 3D meshes GeoFly uses the software "SURE" from nFrames. Together with the nFrames team we are continuously working on the optimization of the true ortho process chain.

fields of application for true orthophotos

• disaster control e.g. flood prevention newspaper articles: Business Geomatics 4/16
• cadastre (outside areas, tree cadastre, etc.)
• topography capturing
• communal applications
• urban planning

You can also visit our Geoshop and order your geodata online.

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