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I have two GeoTIFF referenced files of a tree orchard and when imported into QGIS they are slightly misaligned from each other and I want to ensure alignment of the corresponding tree with each raster so I can undertake zonal statistics. I am using the trees on each corner of the farm on Raster A to be the Ground control points for Raster B. Google maps plugin confirms they are in the right world location.

What causes the Georeferencer to scale up the output file Raster B?

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Illustration showing the offset. Raster A base map is Blue points and Raster B is Red Points. Ideally red should align on top of blue indicating trees in raster A and raster B are aligned.

Left Raster A. Right Raster B

When using Georeferencer with the following settings the output file scale is massive. What settings to I need to effectively “Move” Raster B so it aligns to Raster “A” without any scaling, warping etc.

Steps are

• Create new QGIS project and set Project CRS to EPSG:4326 - WGS 84

• Import 2 raster. Each rasters native CRS is CSD EPSG:4326 - WGS 84

• Open Georeferencer, load Raster “B” make the following settings

Transform Settings

Set the Ground control points. I did 5 GCP. One on each tree in each corner of the farm and one in the middle of the farm using input point from the map canvas option GCP shift is approx .05m and residual pixels value seem small and within expectations.

GCP Shift

GCP Table

Start Georeferencing --> Results

What causes the Georeferencer to scale up the output file Raster B to be so big?

Results - Raster B is much Larger

1 Answer 1

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Looks like this was a bug in QGIS Version 3.28.3-Firenze. Uninstalled 3.28.3-Firenze and installed 3.28.4-Firenze Works as expected.

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