Hi alealbuquerque any updates? were you able to use Parrot calibration target for processing of DJI P4 Multispectral when using Pix4Dfields?
Hi @deg123
Yes I has good results using Parrot Calibration Target. But, ir was necessary read information for target using ASD FieldSpec 4 Hi-Res: High Resolution Spectroradiometer. This done, I used values in Pix4d Mapper and I have had excelents results.
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Hi alealbuquerque,
Thanks for the response hope you are doing well. I’m in a situation you are previously in, however I don’t have access to laboratory measurement for ir. I’d like to ask if its possible for you to share the reflectance values for the parrot calibration panels so I can use DJI P4 Multispectral?
Thank you very much.
Hello @alealbuquerque
We switched from using the Parrot Sequoia Multispectral camera to the Phantom 4 Multispectral. Just like @deg123, we currently don’t have access to a spectroradiometer for infrared. Would you mind sharing your measured reflectance values with us?
Thank you!
I can share with you my informations about my reflectance panel. But, I think each panel has your own data. My data:
Blue: 0,1780
Green: 0,1982
Red: 0,2095
RedEdge: 0,2336
NIR: 0,2882
I hope this can help you
Regard´s
BUENAS TARDES.
NO ME TERMINO DE ENTERAR BIEN.
YO TENGO UN P4MULTIESPECTRAL Y UN PANEL PARROT, QUE VALORES TENGO QUE USAR??
MUCHAS GRACIAS
Hello @davidramosgraciani,
You can reach out to the parrot to see if you get the reflectance factor values for all wavelengths (it will be a graph or a table) and use those values.
This is for DJI P4m: Blue (B): 450 nm ± 16 nm; Green (G): 560 nm ± 16 nm; Red ®: 650 nm ± 16 nm; Red edge (RE): 730 nm ± 16 nm; Near-infrared (NIR): 840 nm ± 26 nm
Buenas tardes.
Cuáles son los valores que hay que poner a la hora de la calibración de las bandas en el pix4dmapper?
Un saludo.
The training video from Pix4dFields shows PIX4D folks using a calibration target. I have asked which one did they use and how was it set up. Jose_Arnaudo with Pix4d has closed my ticket because he says it is a redundant question and check out this post. I do not see anywhere on this ticket that the question was answered. If I missed it please shed some light on which calibration target was used in the video and how calibration was done. Thanks
Hello @jhfr59, Regarding the setup and the use of the reflectance panel, I would recommend you to go through the below video.
Regarding the reflectance panel, PIX4Dfields supports the following reflectance targets: So, you could use any of the below panels.
- Airinov Aircalib
- Parrot
- MicaSense Calibrated Reflectance Panel
- Sentera
For more information on radiometric correction, visit the below support article
Thanks Kapil. This is the video I am directly referring to. I guess I still do not understand how to use with the DJI P4 MS drone. The video makes it seem like a panel comes with the drone which it does not. They use the panel without any details except to take 3 or 4 pictures. They do not identify which panel was used and how it was calibrated, I have read through the articles and for me they are clear as mud. I understand that different sensors require different values to use. However if the work has been done I want that answer, I do not want to have to reinvent the wheel if the work has already been done. The question is not that hard. Which panel was used in the video, where did they buy it, and was there any calibration needed other then what was shown on the video (taking 3 or 4 pictures).
Hello @jhfr59, The steps to use the reflectance panel are to capture the images of the reflectance panel and then upload them along with other images to PIX4Dfields.
If the reflectance panel is supported, Pix4Dfields will automatically, detect it and use the reflectance value so you don’t need to worry about the reflectance values or doing anything. If you go carefully through the video, it explains how you should capture the images of the reflectance panel and also import those images to the PIX4Dfields along with the raw images.
Regarding which reflectance panel is used in the video, it is from Sentera one. However, as I said in the previous reply, you can use the reflectance panel from MicaSense and Sentera.
Thanks Kapil. I ran with a MicaSense panel, However the program indicates that no reflectance panel was found. I followed the video, Is there something I did incorrectly. Thanks
Kapil
One more question. The weather conditions during capture is greyed out so I cannot select overcast or clear sky. This may be part of my problem. As you know the dji multispectral comes with a sun sensor. Is there something I need to do to activate it so I can choose one of the above parameters?
Hello @jhfr59, Can you send us the dataset with the images of the reflectance panel so that we can understand what is the issue?
Regarding the DJI P4 multispectral: radiometric calibration, please read the following.
- The camera is not fully radiometrically calibrated. Only a relative calibration is done by the manufacturer: All bands are calibrated against the standard NIR band. Therefore the camera will not provide reflectance factors, but only relative values that are proportional to reflectance.
- A reflectance target is required to obtain reflectance factors. Without such a target, only indices that are self-normalizing produce meaningful results, i.e. indices that don’t depend on the absolute value. Examples of such indices are NDVI, NDRE, VARI, SIPI2, LCI, BNDVI, and GNDVI. Not self-normalizing are TGI and MCARI.
- The orientation of the sunshine sensor is not known. Therefore the sun angle cannot be accounted for and only the correction type “Sun Irradiance” can be applied. Hence, the weather condition is not required when processing.
Hello Kapil. I researched the panel used in the above video (titled pix4d fields). I went ahead and purchased the Mapir panel $260 + shipping. But now see that this panel is not supported?
Does that mean I have to buy another panel. It’s a shame that the video discussing pix4d fields and reflectance panels, showcase a panel that is not supported.
Thanks
