Does Pix4Dag support VARI algorithms?

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Does Pix4D support the VARI algorithm to evaluate plant health.

Visible Atmospherically Resistant Index. Data is collected with a standard RGB Camera / Sensor.

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2

Hey Michael,
I don’t think VARI is a pre-defined formula in Pix4D however you can make your own formula in Index Calculator. I believe the formula for VARI is:
(Green - Red)/(Green + Red - Blue)

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Hello everyone;

I just tried to apply VARI formula in an RGB based proyect. When pocessed in the desktop version the algorythm seemed to work properly. However when I uploaded it to the cloud, it all went very strange, the “index map” did not show a correct VARI map. 

Please help!

4

Hi Pedro,

Could you please share the URL of the project?

5

Hello Julie. Here it is: https://cloud.pix4d.com/ag/farm/43631/project/307479/map?shareToken=bfeaf2e5933249319803c24cc1512de8

Thank you!

6

If you tweak the histogram values of the VARI map, it should show correct index values as, I believe, the problem you describe is only related to visual display. You can apply a specific range in order to detect the areas on the map falling into that interval.

Does this help?

7

Hi,

Interesting topic. 

I am able to obtain RGB-Vegetation indexes in desktop version but I do not know how to upload a VARI or TGI into the cloud… Could you please let me know how to do it? Thanks ¡¡

8

Hi Pedro,

 

Could you please let me know how you uploaded the VARI file? Thanks,

 

Gonzalo

9

Hi Gonzalo,

 

On Pix4Dfileds Cloud, at the moment it is only the results under the NDVI folder are displayed on the cloud. In case you would like to display VAri you will first have to generate it and after replacing the file in the NDVI folder. 

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The cloud processing works as following:

  • If you upload the images directly via the  web uploader , the images will be automatically processed with _Ag Multispectral Template. _With this template, one is generating automatically NDVI that will further on be displayed on the Cloud.
  • If you upload via the  Pix4D Desktop  application, then the cloud processing will respect the settings that you have selected within the software. Hence if with the software you have created your personalized indices (e.,g. VARI) and opted for their generation then they will be generated on the Cloud as well. However, they will not be displayed since it is only NDVI that we display at the moment. Following you will have to replace the file for visualization. 

 

To create your index, please see: https://support.pix4d.com/hc/en-us/articles/202560489

To automatically generate these indices while step 3 runs you will have to enable them as per the example below:

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Cheers,

Ina

 

10

In the formula given by Pix4D it´s min(1; max(-1; (GREEN − RED) / (GREEN + RED − BLUE) )) but I cannot place in mapper min nor max, and also “;” or “,”
How do I add VARI formula?
Thanks

11

@jzanelli, Pix4Dfields uses the min, max functions to clamp the values between -1 to +1. In Pix4Dmapper you will not be able to clamp the values, you will need to use the original formula for VARI: (Green - Red)/(Green + Red - Blue). You could also use any 3rd party GIS software that has min, max in their raster calculator.

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OK will do

13

Is required the reflectance values or just with the digital values is possible obtain the index?

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Hi,
You can obtain it with both, if you have the digital values is not a problem.