Hi all,


I am trying to find RGB Zoom Photo Pixel values from Thermal Photo Pixel Values. Is there any offset formula for the same.? I am trying this in python.
Drone = M300
Payload = Zenmuse H20T


and M2EA drone.

It looks very interesting what you are trying to do, but I don't understand. Can you elaborate?

LV_Forestry Posted at 8-26 11:22
It looks very interesting what you are trying to do, but I don't understand. Can you elaborate?

HI
Thanks For the reply.
I have identified some points on thermal ortho-photo and plotted in corresponding Thermal Raw Photo through mapping software. (Eg. Agosoft) in my case.
Now I want to know the pixel values of the same point in RGB too. I don't have any information about how Thermal photo and RGB photos are mapped to each other.

All I know is RGB has extra area cover from Thermal as expected from sensor size.

For Eg..
Given - Thermal_T.JPG x=100,y=100
Required RGB_Z.JPG x,y=?

arpit.p Posted at 8-26 20:12
HI
Thanks For the reply.
I have identified some points on thermal ortho-photo and plotted in corresponding Thermal Raw Photo through mapping software. (Eg. Agosoft) in my case.

Ok now i see. Its pretty simple.
If you are using Agisoft Metashape for reconstruction then its a good thing. It means that both thermal and visible raster are georeferenced.
The precision of georeferencing is crucial for the task you want to achieve.
You must use a dedicated GIS software to run a script that will pickup thermal value according to a position selected on the visible Orthophoto.
For instance with QGIS you can use "sample single raster value"

https://pvanb.wordpress.com/2010/02/15/sampling-raster-values-at-point-locations-in-qgis/

I forgot to mention, keep in mind that you must convert the raw DJI thermal images into a TIF image with min max temperature value before processing in Agisoft.
Otherwise you will end up with a huge nonsense raster.

LV_Forestry Posted at 8-26 20:57
I forgot to mention, keep in mind that you must convert the raw DJI thermal images into a TIF image with min max temperature value before processing in Agisoft.
Otherwise you will end up with a huge nonsense raster.

I tried that. Unfortunately processing both thermal and visibal orthomosaic together is impossible and if I use same geo-referencing for both. there's still some shift.
I am able to get points in Thermal Raw from thermal Orthomosaic but how to get the same points in RGB too?

arpit.p Posted at 8-26 21:16
I tried that. Unfortunately processing both thermal and visibal orthomosaic together is impossible and if I use same geo-referencing for both. there's still some shift.
I am able to get points in Thermal Raw from thermal Orthomosaic but how to get the same points in RGB too?

You can't process both at the same time. You must create two different chunk. Important is to use Ground Control Point.
You do not need to measure it with precision, but the most important is that there are matching on both chunk.
When i talk about chunk i ts all about Agisoft process.
Then both rasters must be perfectly aligned.
Otherwise you can use the merge chunk function, but if you did the GCP procedure it must be fine.
A GCP is not necessary a cross painted on the ground. Any not movable object that can be easily recognize is a GCP. A rock, a street corner, sewage water door... Is fine

You may also be obligated to have an ultra high overlap on the M2EA  thermal dataset. Something like 85% maybe more. Because the sensor is very small. I know it takes lot of flight time.

LV_Forestry Posted at 8-26 21:33
You can't process both at the same time. You must create two different chunk. Important is to use Ground Control Point.
You do not need to measure it with precision, but the most important is that there are matching on both chunk.
When i talk about chunk i ts all about Agisoft process.

Thanks I will try!