Vignetting in multispectral orthomosaics when processing in Pix4D Mapper

[joan]

Hello, I processed 400 hectares in various areas, which were flown with a Mavic 3M. The procedures for the multispectral flights were correct, flying at solar noon and using a calibration panel for all flights.

My surprise is that Pix4D (version 4.8.4) seems to create vignetting of the orthomosaics, right at the edges where a clipping box was applied. This throws the reflectivity values ​​off the charts.

I’m going to test processing without the clipping box, but I wanted to share this in case anyone has had the same problem and how to fix it.

Thanks,
Joan

[joan]

I just tried without clipping box and the result is the same. Vignetting around borders.

[Kapil_Khanal]

Hello there, This is happening due to the quality of the raw images. PIX4Dmapper uses the exif information to do the vignetting correction. However, if it is not able to remove it completely then you need to redo the flight or use the data that you have.

[joan]

@Kapil_Khanal

Hello there, This is happening due to the quality of the raw images. PIX4Dmapper uses the exif information to do the vignetting correction. However, if it is not able to remove it completely then you need to redo the flight or use the data that you have.

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Hi, maybe I explained it wrong. The vignetting appears in the orthomosaic, not in the images.

Best regards

[Kapil_Khanal]

@joan

wrong. The vignetting appears in the orthomosaic, not in the images.

Hello @joan, If you are seeing it on the reflectance map, it is mainly due to the presence of it on the raw images or wrong values on the metadata, so try using either Camera Only correction or No correction under Radiometric Processing and Calibration.