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22 comments

• 
  Centro Nacional de Prevención de Desastres April 23, 2019 18:12

  
  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) April 23, 2019 19:43

  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 April 24, 2019 14:30

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

• 
  Holden (Pix4D) April 24, 2019 19:43

  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 April 25, 2019 16:10

  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) April 25, 2019 16:21

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

  Edited by Holden (Pix4D) April 25, 2019 16:22
• 
  Centro Nacional de Prevención de Desastres April 25, 2019 18:14

  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 April 26, 2019 10:14

  Found it:

  https://support.pix4d.com/hc/en-us/community/posts/255588446-Phantom-4-Pro-Camera

• 
  Holden (Pix4D) April 30, 2019 20:49

  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 May 01, 2019 23:19

  I have that:

  

  and I have that:

  

• 
  Holden (Pix4D) May 03, 2019 16:57

  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 October 05, 2019 23:31

  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) October 09, 2019 15:53

  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) October 09, 2019 15:54
• 
  Joshua Doran November 21, 2019 21:01

  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) November 25, 2019 19:07

  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 June 03, 2020 19:04

  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) June 03, 2020 22:14

  Thanks for the update!

• 
  Assako Darel June 30, 2020 21:53

  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) July 06, 2020 16:54

  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?

• 
  Gary Roberson November 03, 2020 01:56

  The GSD calculator looks like a valuable tool.  I also see reference to the camera database.  Is there a convenient way to view the database in a more readable form?

  Also, I do not see the sensor width displayed in the database.  Is this value derived by calculating from another parameter?

• 
  Holden (Pix4D) November 04, 2020 16:24

  Hi Gary. THe camera database can be found using the info in the link below. It can be viewed in any text editor. I recommend Notepad++. Some values are derived from other parameters. 
  
  https://support.pix4d.com/hc/en-us/articles/202559349-Which-Cameras-exist-in-Pix4Dmapper-Database-and-which-Parameters-are-used

• 
  Karina Puma March 11, 2021 19:56

  Hello friend.

  You can help me with a concern about the parrot sequoia camera.

  What is the value of the sensor width?. I used  a value of 4.83 mm. 

  

  or what is the methodology to determine that value. Finding the sensor width value is very complex.

  Edited by Karina Puma March 11, 2021 19:59