Rededge-M vs. Sequoia

PIX4Dcapture PIX4Dcapture Questions/Troubleshooting
21

Hi Momtanu. I’m not sure which reflectance output images to use to create an RGB composite. Under 4_index/reflectance/tiles there are files _noalpha_reflectance and _transparent_reflectance. Which should I use and what is the difference between these? thanks!

Scott

22

You can use either. For what concerns the two TIFF outputs, the “noalpha_reflectance” gives a black color value to the no value data pixels. It will result in a .tiff file with black color where there is no information.
The “transparent_reflectance” does not display color information (it applies a transparent band) to the no value data pixels. It will result in a .tiff file where areas with no are not displayed as black color.

This is similar to orthomosaics: https://support.pix4d.com/hc/en-us/articles/202558809-Transparency-of-the-orthomosaic

23

Thanks for the info Momtanu. I am finding reflectance values > 1.0 in my data. I thought the reflectance values were normalized between 0-1.0. Is this not correct?

Scott

24

If you use reflectance targets, the values should lie between 0-1.

However, in some cases, there might be error. For example, Generally, we do not recommend using the DLS data if there were some scattered clouds (it was not sunny or uniformly overcast). The DLS will take wrong readings only for such pixels which are actually covered under the cloud but the DLS thinks there is the sun for some portion of those pixels. In those cases, we recommend using only radiometric targets and camera only correction (nothing from DLS)

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25

Hi Momtanu, I have case in my project with this situation. Based on your opinion, how confidence you trust the result data from this case?

26

Hi,

Depends on what kind of project you are working on, but we do not give confidence if scattered clouds were on the dataset. Besides, there are some precautions to take into account if having this situation as Montanu said;

As mentioned in the knowledge base, If you have overcast conditions, please select “Camera and Sun Irradiance”. In PIX4Dmapper, selecting sun angle corrections in cloudy conditions leads to biases.