How to fix DEM scanline artifacts

Started by sboerner, January 12, 2021, 11:46:47 pm

Previous topic - Next topic

sboerner

Does anyone know of a way to smooth out these spikes, while keeping the underlying displacement? This is a 1-meter DEM file, and it looks like they're caused by noise in one of the scanlines. I thought a smoothing filter shader (which I've never used before) with a mask plugged into the scale modulator might work, but no.

WAS

Quote from: sboerner on January 12, 2021, 11:46:47 pmDoes anyone know of a way to smooth out these spikes, while keeping the underlying displacement? This is a 1-meter DEM file, and it looks like they're caused by noise in one of the scanlines. I thought a smoothing filter shader (which I've never used before) with a mask plugged into the scale modulator might work, but no.
I think the only real definitive way is a clone tool in Photoshop. Clone as close to the area as possible, and use ctrl + shift to do a straight line (if it is), and follow the scan lines to mask them out with "good" data.

Dune

Maybe they are nodata areas? They can be filled somehow by some check. I also had trouble loading certain DEM's, and had to change to lineair color space. This is why I prefer greyscale tiff's to work with, so best to indeed convert the DEM and clone out.

sboerner

Thanks.

The DEM is an img file, not a tiff. Not sure how I'd convert that to something editable, but I'd rather not anyway because it is part of a matrix of 50+ DEM files that have been tiled to create a large-scale scene. The artifacts aren't no-data areas - I did check that. The good news is that they are in the background. I am saving out the combined DEMs as a ter heightfield file, and found that if the resolution is reduced most of the artifacts average out. So problem solved this time. 

I guess I was hoping there might be a procedural way to fix things like this, but understand why there isn't.

Dune