Hi everyone. I used DJI terra(V3.9.4) to process M3M multispectral images, and finished radiation correction by two plates, when I check the single-band images by Qgis, I found they are not normalized to 0-1, what happened

Divide by 32768. middle of the 16Bit space

LV_Forestry Posted at 3-16 02:59
Divide by 32768. middle of the 16Bit space

Thanks my dear friend. I'm not the expert in this area, if I divided by 32768, the range of "result_NIR" will be like 0.001258-0.102582, is that right?

fansbea42186 Posted at 3-16 04:54
Thanks my dear friend. I'm not the expert in this area, if I divided by 32768, the range of "result_NIR" will be like 0.001258-0.102582, is that right?

It's possible. But from your screenshot with reflectance panel, i assume that something is wrong.
M3M is designed to be used with the Solar sensor and does a good job in that way.https://dl.djicdn.com/downloads/ ... essing_Guide_EN.pdf



Also be aware of that which is valid for both P4M and M3M :
Faulty Red-Edge Band | DJI FORUM

LV_Forestry Posted at 3-16 05:09
It's possible. But from your screenshot with reflectance panel, i assume that something is wrong.
M3M is designed to be used with the Solar sensor and does a good job in that way.https://dl.djicdn.com/downloads/ ... essing_Guide_EN.pdf

Thanks again for your posts. I read them all and tried some tests. I update the Terra to V4.0.8, and used the same data to processed again, the strange things happed, the values looks normal now. This just a part of my experient area, I will rebuild the whole area and see if it is ok.

Is there possible I can simply normalize the value to 0-1, or if I must divide by 32768 ?

syqkyle Posted at 3-16 08:44
Thanks again for your posts. I read them all and tried some tests. I update the Terra to V4.0.8, and used the same data to processed again, the strange things happed, the values looks normal now. This just a part of my experient area, I will rebuild the whole area and see if it is ok.
[view_image]

In the "update" raster, the values are normalized from 0 to 1 if you divided by 32768.

QGIS displays the minimum and maximum values by default. Feel free to adjust from 0 to 1 in Properties -> Histogram if you want to visually compare the image.

If you are doing computer analysis, there is no need.

LV_Forestry Posted at 3-16 11:35
In the "update" raster, the values are normalized from 0 to 1 if you divided by 32768.

QGIS displays the minimum and maximum values by default. Feel free to adjust from 0 to 1 in Properties -> Histogram if you want to visually compare the image.

Thanks my friend, I will follow your advice.