TOOLS - GSD calculator

Click HERE to download the tool in Excel format.
Click HERE to download the tool in Open Office format.

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19 comments

  • Centro Nacional de Prevención de Desastres


    We have a phantom 4 and I entered that      parameters as show in the picture, then we fly the drone and when we entered the flight height the app Pix4DCapture says GSD 5.5, so, the question is Why it does not say 0.77?

  • Holden (Pix4D)

    Hi there. The camera database has the focal length of the Phantom 4 as 3.61, not 20. can you input the correct focal length to see what value is produced?

  • Centro Nacional de Prevención de Desastres

    Ohh very thanks, now the value GSD is 4.27 It's ok?

  • Holden (Pix4D)

    The sensor width is also incorrect. The database has it as 6.3175. Where did you get these values from?

  • Centro Nacional de Prevención de Desastres

    I asked a DJI advisor, I also saw it in the following table:

    According to the specifications on the official DJI page the sensor is 1 / 2.3"

  • Holden (Pix4D)

    I dont see the P4 on the list. Do you have any documentation that shows that size?

    Edited by Holden (Pix4D)
  • Centro Nacional de Prevención de Desastres

    I do not have a document of that information because the advice was an online chat of DJI support but if necessary I ask for it again by mail to justify the parameter

  • Spiros Arethas
  • Holden (Pix4D)

    Those refer to the Phantom 4 Pro. The above is in relation to the Phantom 4 which has a different sensor. 

  • Centro Nacional de Prevención de Desastres

    I have that:

    and I have that:

  • Holden (Pix4D)

    One of my smart colleagues had the answer. Thanks, Andrew!

    "The 20 mm focal length that DJI reports in the camera's specifications is the 35 mm equivalent focal length. The camera's actual focal length is significantly smaller than 20 mm because the camera's sensor is smaller than a standard 35 mm sensor"

  • Jason Kennedy

    There is one very, very important variable missing in this equation for calculating GSD: PIXEL PITCH. Without pixel pitch, you get a much lower (higher res) GSD.  Therefore, this calc does not give a true GSD. 

  • Holden (Pix4D)

    Hi Jason. The pixel pitch is estimated by dividing the sensor size in mm by the number of pixels in each dimension. Both are passed to the calculator.

    Edited by Holden (Pix4D)
  • Joshua Doran

    How can I find the proper sensor width and focal length for the mavic pro and the zenmuse x5s? The numbers on the DJI website seem to be different than what people are posting here about their specific lenses.

  • Holden (Pix4D)

    Hi Joshua. Generally, anything posted by the manufacturer is correct. Sometimes focal length can differ depending on if its real of 35mm equivalent. You can also refer to the camera model used in Mapper by opening the image properties editor and looking at the parameters for the camera model loaded. 

  • ujjal deka baruah

    Hi Holden,

    I would like to highlight and help you an others as well regarding focal length. Here Holden is correct about "The 20 mm focal length that DJI reports in the camera's specifications is the 35 mm equivalent focal length. The camera's actual focal length is significantly smaller than 20 mm because the camera's sensor is smaller than a standard 35 mm sensor"

     

    Below is the DJI Phantom 4 pro photo details . As you can see focal length is 9mm and but camera specs tell it is 20 mm. So i guess focal length varies. To check the focal length you can simply check the image details. if you are on windows just right click on the photo and go to 'details' tab. You will find what you need. Thanks

  • Holden (Pix4D)

    Thanks for the update!

  • Assako Darel

    Hello, please, what is the impact of Yaw, Pitch, Omega, Phi, Kappa angles on image accuracy and the quality of geospatial measurements with a UAV?

    I also need a GSD calculator working material, I tried to download the one on the site, but it is protected and available in read-only. Please provide it to me

    regards

  • Holden (Pix4D)

    Hi Assako. The impact of these options is talked about in the "processing options" section of the article below. 

    https://support.pix4d.com/hc/en-us/articles/202558969-Yaw-Pitch-Roll-and-Omega-Phi-Kappa-angles

    Can you provide screenshots that show where the read only issue is occurring?

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