I'm trying to interpolate a point file that comes from a surface water model output. Each subgrid point has an elevation, and that was used with the cell water levels to generate values for percent of period record inundated. I want to smooth out the blocky shape for a few reasons that aren't important to get into here. I'm using Qgis for a few things that I'd need a more expensive license in Arc.

So here's my grid of points. Cancel that, I'm only allowed to post two images. The points are 130' apart.

I set it to 25' resolution and ran the interpolation. This is what resulted.You can see the point layer in the background

The right third is beautiful and exactly what I want, but the left two thirds are all screwed up. I thought it might be the non-rectangular shape, so I exported a perfectly rectangular set but that didn't help. I tried adjusting everything I could think of to no avail. I tried to manipulate the projections, but I'm not very good with Q and couldn't figure that out.

The one thing I did that seemed to elucidate it was I cut out a section of points to the left of the part that worked, and tried that. enter image description here

Amazingly that worked. It looks like the TIN basically only will do a certain width. I may have a lot of these to do and really don't want to have to chop them all into pieces and then glue them back together. There's got to be a solution to this. Any ideas?

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