Camera distortion

Undistorting with camera parameters

Due to lens properties, images taken with almost all cameras are distorted and a correction step needs to be applied to process them properly. As seen in the input image, the square grid is deformed when captured by the camera. Therefore, it can be difficult to match features in different images, especially close to the borders of the images. This is automatically taken into account during processing with Pix4Dmapper.

Pix4D Desktop estimates the distortion parameters for the camera during step 1.Initial Processing. These parameters are used internally to undistort the images. For further processing, it is possible to save the undistorted images: Menu Process > Save Undistorted Images.

Original image: The square grid is distorted because of the lens of the camera.  Undistorted image: The square grid is now perfectly aligned.

Rolling shutter effect

Some cameras have a shutter mechanism called a rolling shutter. This means that the image is read line by line and moving the camera during this reading time creates artifacts in the image. 

In the case of a linear flight plan, such as a grid flight plan or the regular mapping of a facade, Pix4Dmapper can model the rolling shutter and therefore increase the accuracy of the reconstruction. To use this feature, the correct shutter model must be selected: How to use the Editing Camera Model Options.

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1 comment

  • Ilkka Korpela


    This Pix4D feature is really cool, but to make it even better, can you explain how to interpret
    the image coordinate system with respect to the camera coordinate system?

    Is the optical axis now in image center (no offsets in principal point location with respect to the center pixel of the undistorted image)?
    Is the pixel size same as in the original image (in millimeters)? 

    Ilkka Korpela, U Helsinki

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