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I am working on a project for the university and have to use TIN-Interpolation to analyse the raster. I have the issue that the raster doesn't fit to the points. I found a post that recommend to covert them into vector points but that also doesn't work out. Does someone have a tip what could cause this problem?

TIN-Interpolation

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  • Hi Philip, and welcome to Gis.Stackexchange! Feb 9, 2022 at 16:17
  • Could you please specify if the gray octagon is the output raster of the interpolation process from the red dots? If so, there is a scale problem (I would estimate a 2x scale factor). Could you also share some details about the reference system (CRS) of the point vector and of the output raster? Feb 9, 2022 at 16:19
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    Thanks for you answer! Yes that's right, the Gray octagon is the output of the red dots with the TIN interpolation function. I also used the red dots layer as expansion Layer. The reference system is 5650. A reference System for Bavaria, Germany. I didn't found a scale option in the TIN function. When i select the red dots as expansion layer he sets the size automatically. I saw videos on youtube where this works perfect. But i get this strange result. I would guess that there is something wrong with the basic settings but i checked everything i could found in the internet so far.
    – Philip
    Feb 9, 2022 at 16:37

1 Answer 1

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Check CRS coherence

This sounds like a CRS mismatch problem.

Probably your input dataset (the point vector file) has a CRS (EPGS:5650) while your project has a different one.

Start out by making sure they are both on the same CRS:

  1. Edit the CRS of the project: Menu Project->Properties, select CRS, set it to EPGS:5650

enter image description here

  1. Check/Set the layer's CRS: Right click on the layer's name ->Layer CRS->Set Layer CRS..., then choose the same CRS (for example EPGS:5650)

  2. Only then use the interpolator, taking care to set a proper pixel size:

enter image description here

and hopefully the output raster will be aligned with the input points layer.

enter image description here

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    I controlled it but it didn't work. So i tried something else. I was working on a mac using qgis 3.22. Now i installed version 3.16. and here its working fine even in an old file. So i guess there is something wrong with the mac Version. Thanks a lot for you help!
    – Philip
    Feb 9, 2022 at 18:33

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