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Platform: Windows 11

1. Aim trying to achieve: I have some very high quality multispectral data (drone multispectral imagery), from which I am trying to create an orthomosaic. My multispectral data consists of .tif files in G band. I need a GeoTIFF orthomosaic which is also georeferenced.

2. Steps followed for georeferencing: First I converted the raw .tif files into georeferenced .tif files with GDAL. The files already had GPS metadata. Below is the gdalinfo for one of the georeferenced .tif file:

Driver: GTiff/GeoTIFF
Files: DJI_20231104164259_0001_MS_G.TIF
Size is 2592, 1944
Coordinate System is:
GEOGCRS["WGS 84",
    ENSEMBLE["World Geodetic System 1984 ensemble",
        MEMBER["World Geodetic System 1984 (Transit)"],
        MEMBER["World Geodetic System 1984 (G730)"],
        MEMBER["World Geodetic System 1984 (G873)"],
        MEMBER["World Geodetic System 1984 (G1150)"],
        MEMBER["World Geodetic System 1984 (G1674)"],
        MEMBER["World Geodetic System 1984 (G1762)"],
        MEMBER["World Geodetic System 1984 (G2139)"],
        ELLIPSOID["WGS 84",6378137,298.257223563,
            LENGTHUNIT["metre",1]],
        ENSEMBLEACCURACY[2.0]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["geodetic latitude (Lat)",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["geodetic longitude (Lon)",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    USAGE[
        SCOPE["Horizontal component of 3D system."],
        AREA["World."],
        BBOX[-90,-180,90,180]],
    ID["EPSG",4326]]
Data axis to CRS axis mapping: 2,1
Origin = (77.533600277777794,23.247076472222201)
Pixel Size = (0.000001000000000,-0.000001000000000)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_DATETIME=2023:11:04 16:42:59
  TIFFTAG_IMAGEDESCRIPTION=default
  TIFFTAG_SOFTWARE=10.12.05.45
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  77.5336003,  23.2470765) ( 77d32' 0.96"E, 23d14'49.48"N)
Lower Left  (  77.5336003,  23.2451325) ( 77d32' 0.96"E, 23d14'42.48"N)
Upper Right (  77.5361923,  23.2470765) ( 77d32'10.29"E, 23d14'49.48"N)
Lower Right (  77.5361923,  23.2451325) ( 77d32'10.29"E, 23d14'42.48"N)
Center      (  77.5348963,  23.2461045) ( 77d32' 5.63"E, 23d14'45.98"N)
Band 1 Block=2592x1 Type=UInt16, ColorInterp=Gray

3. Steps followed for generating orthomosaic: I created a list of .tif files and stored the names in a text file. Then I ran this command:

gdal_merge.py -o mosaic.tif --optfile tiff_list.txt

4. Output: This gave me an output, but not what I wanted. The output orthomosaic was just all the .tif files stack on top of each other, I guess there is no blending of common pixels between them (although all the images have 80% of overlapping).

What else can be done here?

The output: This is in PNG format (original output is in .tif file and is a large file)

Improve this question
8
  • Are you able to get IMU data (roll, pitch yaw) from the drone or images?
    – Cary H
    Commented Apr 24 at 18:58
  • Explain your conversion from raw.tif to georeferenced.tif? Are you sure you have georeferenced images and not geotagged images? Is this answer helpful? gis.stackexchange.com/questions/468347/…
    – GBG
    Commented Apr 24 at 21:38
  • 1
    @CaryH If I check the exif metadata (with exiftool), it displays the Gimbal roll, pitch, yaw degrees.
    – DevM
    Commented Apr 25 at 5:54
  • I had used a script with osgeo gdal python bindings, I used SetGeoTransform() and SetProjection() member functions to make it georeferenced (WSG-84). To cross verify the georeferencing, I plotted my tif file to qgis. It was not accurate, I will have to make some changes to it. Maybe that is what causing this issue.
    – DevM
    Commented Apr 25 at 6:28
  • It looks like your images may be spun 180. Are you using any code to adjust the orientation of the image?
    – Cary H
    Commented Apr 25 at 11:59

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