Forum

Author Topic: Aerial Orthophotos of Multispectral Camera // settings for colouring / grey?  (Read 2499 times)

toxicmag

  • Jr. Member
  • **
  • Posts: 87
    • View Profile
Dear community,

i am using a MicaSense RedEdge-M for creating orthomosaics from aerial inspections.

In a single project i create a new chunk for every flight i did.
Processing is always done with the same parameters.

Viewing the different Orthomosaics in the separate chunks is strange. Sometimes they appear almost like RGB; sometime just grey like a single band.

Palette settings, or raster transformation was not touched.

Any ideas?

Thanks a lot
Alex
#multirotor #VTOL #Trinity #Quantum-Systems #a6000 #a7R #RedEdge #ALTUM #RX1II

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13297
    • View Profile
Hello Alex,

By default PhotoScan in the ortho view would display RGB colors if it can find the bands marked as Red, Green and Blue among the source channels. Otherwise, only the first band will be displayed by default.

So if you usually see RGB representation for RedEdge camera by default, but for certain dataset it is not working, then there might be some issues with the source imagery and meta information. Are you using latest PhotoScan Pro version 1.4.3?
Best regards,
Alexey Pasumansky,
Agisoft LLC

toxicmag

  • Jr. Member
  • **
  • Posts: 87
    • View Profile
Hey Alexey,
thanks for the quick reply.

It's 1.4.3 build 6529 (64bit) which i am using and the reason might be, that for the first chunk i copied all Micasense files to a single folder before adding them in PS. I was doing so, cause i did not like the Micasense way to create all these subfolders on the SD card.

At the second dataset i simply uses the "add folder" option and gave PS all folders and subfolders at one...  :D  A little lazy, but this one is displayed in RGB.  ::)

Is there a way to correct the first dataset other than re-processing it all?

Greetings

Alex
#multirotor #VTOL #Trinity #Quantum-Systems #a6000 #a7R #RedEdge #ALTUM #RX1II

toxicmag

  • Jr. Member
  • **
  • Posts: 87
    • View Profile
Hello Alexey,

with the current version of Metashape (1.5.2.7838) i experienced another issue yesterday.

I did a comparison between Micasense Rededge-M and MX after there was a firmware update from Micasense and created 2 different chunks for this.
I wanted to check the PPK process and the offset of the Orthomosaics later.

When the processing was finished the Orthos looked not like RGBs but more like green and blue colors. Looks like red might be missing, even though every exposure has all bands available. Primary channel is set to default.

Because it looks like red band is somehow missing, i switched the primary band to red and found a black ortho (birghtness level gives no improvement here), even though all bands are fine in their single TIFs.

Panel calibration is partly failing (s. attachement) and 2 bands are not detected automatically. This might be another reason. On the other hand when i import panel settings manually it shows nothing better.

Thanks for possible ideas.

Greetings from Germany

Alex
#multirotor #VTOL #Trinity #Quantum-Systems #a6000 #a7R #RedEdge #ALTUM #RX1II

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13297
    • View Profile
Hello Alex,

Can you please provide the processing log related to the Calibrate Reflectance operation?

Also when you say that you have manually input the reflectance values for Red and NIR bands, have you also manually applied the masks to the corresponding calibration images? If the masks have not been applied to all the bands in the calibration images that contain the panel, such images would be skipped.
See Appendix A of the related instruction:
https://agisoft.freshdesk.com/support/solutions/articles/31000148780-micasense-rededge-mx-processing-workflow-including-reflectance-calibration-in-agisoft-metashape-pro
Best regards,
Alexey Pasumansky,
Agisoft LLC

toxicmag

  • Jr. Member
  • **
  • Posts: 87
    • View Profile
Hello Alexey,

thanks a lot for your reply.
I know it's not easy to deal with all the different camera models and fw updates and settings and stuff...

Ok, so:

1) I didn't know what exactly you mean. Is there a separate log i can create for the panel calibration, or is it the concole messages i could add here?

2) When i imported the values manually, i did so by importing the corresponding csv-table to my panel. The two missing bands were then filled out.
So i followed your recommendation and by zapping through the primary channels to find out about the masks i found images of specific bands that had no mask at all. I corrected this by applying a new mask and everything is fine now.

So what i learned now is to check this manually and to take the calibration pictures at a shorter distance (they were maybe too small for autodetection of the grey panel).

It could be also a nice feature for those users who do multispectral work if Metashape would give a notification if masks are missing after autodetection (or is it that ratio given by numbers i.e. 3/5 in the calibration dialogue?) or if the size or shape of the masks varies too much between the bands (which indicates a faulty autodetection).

Nevertheless thanks for your great support and looking forward to compare now the RedEdges against the ALTUM.
:)

Greetings

Alex
#multirotor #VTOL #Trinity #Quantum-Systems #a6000 #a7R #RedEdge #ALTUM #RX1II

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13297
    • View Profile
Hello Alex,

In the Console pane of the Metashape Pro window you should be able to see, if all the bands are considered during the reflectance calibration operation or some are skipped (for example, if the masks are not applied).

The ratio in the panels section of the Calibrate Reflectance dialog indicates, how many bands from the total number (per camera location) have the masks applied. So in proper case it should be 5/5 (or 5/6 for Altum camera, since thermal band doesn't require calibration).

The masks are applied basing on the location of the QR-code. If it is misplaced or not seen on the image, then the mask couldn't be applied automatically.
Best regards,
Alexey Pasumansky,
Agisoft LLC