Cannot export orthomosaic from DJI P4

[vladal]

I have a set of images from DJI Phantom P4 multispectral camera. It did well in alignment, dense cloud, DEM and orthomosaic generation. However, I am having trouble with orthomosaic export (DEM exported fine).
Particularly, I'm getting a .tif orthomosaic with values, but the histogram is blank and the image itself is black.

I tried 3 settings in Raster Calculator - (a) unmodified, (b) divided by 32768 - same result, (c) divided by 65535 - export error (could not create file).
In Calibrate Reflectance I marked 'Sun Sensor'.

Agisoft Metashape version is 1.8.4


Am I missing something?

[Keith Johnson]

Not sure if this applies to your situation -- I also could not export an orthomosaic, but could export the DEM --- or rather, it output a file but reported an error.  The file was 4.29 GB and could not be opened in QGIS.

In the Export Orthomosaic - TIFF panel, turn on "Split in blocks" and set to something under 20k x 20k pixels.

That created a set of tiles which QGIS loaded correctly.

[vladal]

Keith, thank you for your reply.

I tried your approach with tiles and got several files, but they were also blank and black.

I did overcome the error when bands where divided by 65535 (Big TIFF flag in the Export Orthomosaic settings), however I still got a blank black TIFF that looks the same in QGIS or ArcPRO, and makes ENVI crash when I tried to open it. Either way, it seems that by the reflectance values - 32768 is the value to divide by.

Also, I've noticed that the Sun Sensor setting does not persist - I mark it and press "OK", but the next time I open it, it is unmarked.

[Alexey Pasumansky]

Hello vladal,

If you are still having the difficulties with orthomosaic export, please provide the following screenshots:
- Transform tab of Raster Calculator dialog with all the input bands and output formulas visible,
- Palette tab of Raster Calculator dialog for any of the output formula (for example, B1, then on Palette tab press Update and Auto buttons before taking the screenshot),
- Export Orthomosaic dialog with all the parameters that you are using.

[vladal]

Hi Alexey
I re-did the project from the start yesterday and I got the orthomosaic right this time.
I think the problem was that initially in Camera Calibration I did not select all of the fixed parameters (b1, b2, k4 were not marked).

I did want to make sure, is it normal that in Calibrate Reflectance when I select "Sun Sensor" and press OK, Metashape does a calculation and the window closes, but the next time I open it Sun Sensor is not selected?