Support Website Contact Support Blog

ExposureTime effects correction

Hello,

I am researcher in the field of remote sensing,However, I have very less experience in the field of agriculture and photography.

  • So, I am trying to understand, initially, how things works.
  • There is, Exposure Compensation, mathematical formula in following Pix4d document which I am unable to make any sense of how it is working.
  • p′ = p^( k^2/τK)

Can anyone help me out regarding maths behind above formula mentioned on Page 7/10 in following document.

https://support.pix4d.com/hc/en-us/articles/204894705-Camera-Requirements-for-Precision-Agriculture#gsc.tab=0

Regards.

Dear Uzair,

What this formula is saying is that the new pixel value (p’) is equal to the old pixel value § times a multiplicative correction factor. This multiplicative factor is written in the paper and depends on the ISO level, the aperture f number and the exposure time. The new pixel value p’ is the one that is used for the computation after this correction is taken into account. 

However, you do not have to worry about the details of the implementation: if you choose Camera Only for the radiometric correction in the processing options for the third step (see https://support.pix4d.com/hc/en-us/articles/203891879 ), these factors will be taken into account automatically (provided the EXIF tags are written in each image). You can find a list of the EXIF tags read by the software here

https://support.pix4d.com/hc/en-us/articles/205732309-EXIF-Information-read-by-Pix4Dmapper

along with the units. 

Best regards,

Do you use the same equation to correct pixel values based on shutter speed when dealing with the Parrot Sequoia?