NIR and Red Edge values are over 1

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi there,

I have been using Pix4D to process RedEdge-M images. I am new in this area. When I processed a new dataset, and found that the values of NIR and Red Edge are over 1.0. I know there must be something wrong, but can you please let me know what are the possible reasons and how can I correct them?
image

Thank you a lot for your help in advance.

Regards,

1 Like
2

Hi,

Not using the reflectance target could lead to this. Did you use one?

3

Hi Jose,

Is reflectance target reflectance panel? If so, Yes I used.
If I do not use it, the calibration for each camera is yellow !

image
image803×732 52 KB

with these inputs, will outputs be correct?

Thanks.

4

Hi Jose,
Let me jump into the discussion.
Yes - we did use the reflectance target, that’s why it seems rare to me to have reflectances above 1. Would you guys have any tip on what we should do to correct this?

5

Hi,

Could you make sure the reflectance panel images and well taken? Not shadow, no over exposure. You can check clicking “Calibrate”.
You can read https://support.micasense.com/hc/en-us/articles/1500001975662-How-to-use-the-Calibrated-Reflectance-Panel-CRP-

Besides, make sure the values that are shown under “Calibrate” are correct, you can write to Micasense support https://micasense.com/prv/ asking for the values of your panel.

Last, you can check if any image is over exposed that could giving some outlier and not process it, or, process using “Correction Type: camera only”

Hope this helps.
José

6

Hello Jose,

  1. Reflectance panel images double checked - were well taken
  2. Panel reflectance values used were suggested by MicaSense - according to its serial number
  3. Reprocessed using ‘camera only’ settings. Minimized a lot, but still presented values above 1 (white gaps in the figs below).

NIRrefl_over1
NIRrefl_over11844×2512 1.07 MB

Fig 1 - Top and mid: processed using ‘Camera, Sun Irradiance and Sun Angle using DLS IMU’; bottom: processed using ‘Camera only’

BTW, sky conditions were very clear.

Any suggestion?

7

Hi,

Thanks for the information sent. Could you send the log files(\project_name\project_name.log).

Best,

8

Links for the logs of the two runs below:

One thing it came in my mind. I’m not sure if it has to do with, but RedEdge firmware wasn’t updated in this specific flight.
Soon we’ll be able to take another flight with updated firmware, so we can discard this hypothesis.

Many thanks for the follow-up, Jose. And will be waiting for the .log analysis.

9

I see that the Calibration target was used for each band and Sun irradiance correction was applied, nothing wrong.

Let us know after the firmware update.