Interpolation results smaller than field boundary

[felippehsk]

Hi @gustavowillam,

As I mentioned on Issue #3 there are a few fields which the interpolation results are a bit smaller than the field boundary. Result of a very "tight" bounding box. In my opinion a buffer on the bounding box should solve the issue. I attached an image representing what I am talking about. In purple you see the points I am using for interpolation, on Red-Yellow-Green scale is the interpolation result and the line represents the boundary delineation.

I also believe that a buffer could help solving some of the situations when the issue #3 is observed.

Please, let me know if you need an further information or an extra hand as a contributor!

[gustavowillam]

Hello @felippehsk! I used the data you provided to perform the interpolation. The plugin references the center of the pixel to determine if it is part of the outline or not. In this image below I used a size 5 for the pixel, so it delimited the outline with greater precision.

In this other example, the pixel is with size 15, so its center is further away causing a less precise delimitation, as can be seen in the figure below.

A possible solution would be to perform the interpolation in the plugin without using a contour polygon. With the map interpolated by Smart Map, use the QGIS function: Clip Raster by Mask Layer. I tested it here and the result was very close to those produced by the plugin. Abraços!

[sarviovalente]

Dear all,

Another simple solution is. Make a buffer using your border polygon.

Best Sarvio

Em seg., 16 de ago. de 2021 às 16:33, Gustavo Willam < @.***> escreveu:

Hello @felippehsk https://github.com/felippehsk! I used the data you provided to perform the interpolation. The plugin references the center of the pixel to determine if it is part of the outline or not. In this image below I used a size 5 for the pixel, so it delimited the outline with greater precision. [image: image] https://user-images.githubusercontent.com/42176577/129617197-c49dcdbc-269f-404e-bd7c-6a741979996b.png

In this other example, the pixel is with size 15, so its center is further away causing a less precise delimitation, as can be seen in the figure below. [image: image] https://user-images.githubusercontent.com/42176577/129618560-fc9359c1-c8be-4179-95b3-d0d92b79413e.png

A possible solution would be to perform the interpolation in the plugin without using a contour polygon. With the map interpolated by Smart Map, use the QGIS function: Clip Raster by Mask Layer. I tested it here and the result was very close to those produced by the plugin. Abraços!

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[felippehsk]

@gustavowillam, thank you for the reply!

Definitely. That is how I have used it before. Instead of using the boundary within the plugin, I would interpolate it and later clip the raster based on the boundary. As @sarviovalente mentioned, getting a buffer from the boundary would be a great solution.

I can do both scenarios and that would not be a problem! However, thinking about making it easier for the user, it would be ideal if all the activities would performed within the plugin. This is my personal opinion as well as what I heard from other users.

@gustavowillam, let us know what are your thoughts!

[gustavowillam]

Correct @felippehsk

I will implement a buffer for the contour polygon. Once it's done, I'll make it available in the next version of the plugin. Thank you for your contribution.

[felippehsk]

Sounds good, @gustavowillam! Thank you so much for working on those issues!