[Qgis-user] Trouble in georeferencing

[Patrick Dunford]

Hi, you should read the documentation for this tool, as at least four 
points are needed for a projective transformation.

https://docs.qgis.org/3.16/en/docs/user_manual/working_with_raster/georeferencer.html

This is probably the reason for distortion, but if the original is 
oblique, as implied by the use of the projective transformation, it can 
be hard to mark points accurately.

Output quality depends on the resampling method chosen. It is also of 
course affected by the original quality.

On 31/01/22 06:35, Akanksha Chugh wrote:
> 1.I clicked on Raster>Georeferencer
> 2. Open raster>Add points (X and Y)
> 3. Open Transformation settings
> 4. Define transformation type as projective, resampling method as 
> nearest neighbour, target SRS as EPSG:4326- WGS 84, Compression as 
> none and then ok.
> 5. Start georeferencing.
>
>
>
>
> On Sun, Jan 30, 2022, 10:21 PM Patrick Dunford 
> <enzedrailmaps at gmail.com> wrote:
>
>     Ok. Can you give us a bit of detail of what you're trying to do.
>     List the steps that you undertook to get this result.
>
>
>     There are a lot of possible factors that can cause blurring, which
>     includes the resolution of the source raster, and the
>     transformation method employed.
>
>     Assuming you're using aerial photography, there are technical
>     factors that can cause visual distortion of distances.
>
>     On 31/01/22 02:10, Akanksha Chugh wrote:
>>     Raster>Georeferencer
>>
>>     On Sun, Jan 30, 2022, 6:38 PM Patrick Dunford
>>     <enzedrailmaps at gmail.com> wrote:
>>
>>         Wjat is the name of the tool or plugin you are using.
>>
>>         On 31/01/22 01:25, Akanksha Chugh wrote:
>>         > There appears black area around the image and also it is
>>         stretched out
>>         > and blurred.
>>         >
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