Before anyone marks this as a duplicate, hear me out. This question:
asks my question but not for QGIS. Furthermore, the answer is vague and not entirely useful. That being said...
My problem is simple. I have xyz data for a river. The river is curved, and I would like to produce a bathymetric map of the bottom. Interpolation is the (nearly) perfect tool. I struggle to get maps that do not highlight the actual data points. The blending is quite poor, and I think this is because the interpolation is happening on a square, or a polygon, depending on which method of interpolation in QGIS you use. The tool does not know that the area of interest is a strange and specific shape!
Is there any way or plugin to tell QGIS to focus the interpolation from a line (which I would draw down the center of the river, or a polygon, (which I could draw outlining the river) in order to interpolate in a very specific area?
I do not want to use a polygon to clip my interpolation result. It is extremely close to what I want but I feel like the rest of the interpolation that I do not want is affecting the river.
I have a feeling GRASS can do this. If someone can confirm this and tell me the function I will learn how to use GRASS (although I'm kind of scared of it). If there is a function or plugin in QGIS that would be awesome. Thanks for the help people!
Adding this image to help with a comment I made. Demonstrates the problem and also another issue with the actual path of the sensor being too visible.