How to smooth convex surfaces using a whitebox tool ?

[lucas parisi]

Good morning,

I have a question regarding tools related to convex surfaces at the surface of a raster. We scanned a ski slope last summer at a ski resort with a Lidar and a drone and my team and I would like to know if, with one of the tools from WhiteboxGeospatial, it would be possible to detect convex surfaces (potentially extended over several meters) in order to "remove" them from the raster by replacing them with planar surfaces that follow the slope of the ski slope?



For example here are the profiles of a ski slope. The curve in black color is the raster 0 without snow, in light blue is the raster with the snow and in yellow/red/green are differents results of the Gaussian filter that I applied on the raster 0 (in order to smooth the surface). But the Gaussian filter is not what I am looking for.
So here, how could I detect and smooth convex surfaces in order to have something more like the blue raster ? 

The goal is to make the raster as smooth as possible!

Thanks in advance for you answer !

Lucas

[Whitebox Geospatial Inc]

Good morning Lucas,

 

In the past we have encountered this problem when we’ve needed to remove residual vegetation from our lidar DEMs, after interpolating last-returns only. We’ve come up with the following approach, although I should say that it does rely on functionality in Whitebox Workflows for Python Professional.

 

 

And here’s an example of how well it works:

 

I think we can agree, the technique can work very well indeed. I hope that helps you out.

 

Regards,

 

John

 

From: whiteb...@googlegroups.com <whiteb...@googlegroups.com> on behalf of lucas parisi <l.pari...@gmail.com>
Date: Monday, April 3, 2023 at 5:16 AM
To: WhiteboxTools <whiteb...@googlegroups.com>
Subject: How to smooth convex surfaces using a whitebox tool ?

Good morning,

I have a question regarding tools related to convex surfaces at the surface of a raster. We scanned a ski slope last summer at a ski resort with a Lidar and a drone and my team and I would like to know if, with one of the tools from WhiteboxGeospatial, it would be possible to detect convex surfaces (potentially extended over several meters) in order to "remove" them from the raster by replacing them with planar surfaces that follow the slope of the ski slope?

For example here are the profiles of a ski slope. The curve in black color is the raster 0 without snow, in light blue is the raster with the snow and in yellow/red/green are differents results of the Gaussian filter that I applied on the raster 0 (in order to smooth the surface). But the Gaussian filter is not what I am looking for.
So here, how could I detect and smooth convex surfaces in order to have something more like the blue raster ? 

The goal is to make the raster as smooth as possible!

Thanks in advance for you answer !

Lucas

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[Whitebox Geospatial Inc]

Hello Lucas,

 

I am very sorry, I obviously skimmed, read ‘smoothest possible raster’ and jumped to my answer. I can hear the voice of my high school math teacher in my head saying, don’t jump to the answer until you’ve fully read and comprehended the question! Anyhow, with that said, you may want to explore the ShapeIndex tool and as well the multiscale version of the shape index provided by the MultiscaleCurvatures tool. This can be used to map convex landforms, which can then be punched out of the DEM and then interpolate across the void using the fill missing data tool, as in the script below (see the ‘con’ statement for punching out and the fill_missing_data function for filling back in). I hope that helps.

 

Cheers,

 

John

 

From: Lucas Parisi <lucas....@eldatechnology.fr>
Date: Monday, April 3, 2023 at 6:48 AM
To: Whitebox Geospatial Inc <sup...@whiteboxgeo.com>, lucas parisi <l.pari...@gmail.com>, WhiteboxTools <whiteb...@googlegroups.com>
Subject: RE: How to smooth convex surfaces using a whitebox tool ?

Thank you for your reply John.

Unfortunately, this is not the answer I was looking for.

Indeed, with PDAL and other libraries in Python, we are able to easily remove residual vegetation from our lidar DEMs.

What I am looking for is a tool that can detect convex surfaces on a raster and remove them.

Regards,

 

Lucas

 

 

 

	Lucas PARISI
	CPO
	+33 (0)6 61 01 70 74
	@   lucas....@eldatechnology.fr
	www.eldatechnology.fr
	10 Avenue Edouard Belin, BP 54032       31055 TOULOUSE

 

 

---

De : Whitebox Geospatial Inc <sup...@whiteboxgeo.com>
Envoyé : lundi 3 avril 2023 12:38
À : lucas parisi <l.pari...@gmail.com>; WhiteboxTools <whiteb...@googlegroups.com>
Objet : Re: How to smooth convex surfaces using a whitebox tool ?

 

[Jóhannes Guðbrandsson]

Hi thanks for a wonderful tool

I was wondering if there is any update on the topological breach burn tool?

I am using r.carve from Grass GIS in my pipeline and it would be great
to have a faster tool.

All the best

Jóhannes

[Whitebox Geospatial Inc]

Hello Jóhannes,

This is something that I am actively working on at the moment and we're hoping to release the TopologicalBreachBurn tool sometime either towards the end of this month or beginning of next month. However, we are planning on releasing it as part of WTE rather than WbT. Having just moved two of the WTE tools related to stream network analysis into the open-core, we are looking to invest again in the extension starting with TopologicalBreachBurn. I hope that answers your question and thanks for the interest.

Regards,

John

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From: whiteb...@googlegroups.com <whiteb...@googlegroups.com> on behalf of Jóhannes Guðbrandsson <johannes.g...@gmail.com>
Sent: Monday, April 3, 2023 4:08 PM
To: whiteb...@googlegroups.com <whiteb...@googlegroups.com>
Subject: Topological Breach Burn

 

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