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Valued Contributor
Posts: 517
Registered: ‎10-27-2015
Accepted Solution

SGM Point Cloud EDITING

[ Edited ]

Dear all,

Using SGM with two Worldview3 stereo imageres I extracted a point cloud over an urban area. Now I want to edit/filter the point cloud for have a better DEM. What is the correct workflow in ERDAS IMAGINE? What tools can I use?



For esample: this is a screenshot of the point cloud:

sgm_1.JPG

 

If I do a profile you can see those error point over the buidings:

sgm_02.JPG

 

 

I would like to liminate those error pointS in order to have a better DEM. 

thank you very much

Staff
Posts: 34
Registered: ‎04-19-2016

Re: SGM Point Cloud EDITING

Hi

 

This would likely cover all you need to know: http://community.hexagongeospatial.com/t5/ERDAS-IMAGINE/Using-Point-Cloud-Editing-In-ERDAS-IMAGINE/t...

 

kind regards,

Frequent Contributor
Posts: 153
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

This was good - however one further request I have is that if you want to do manual edits like in traditional photogrammetric work then we have good tools in Terrain Editor in Photogrammetry. However it has limitation to have stereo model while editing so you can not edit pure LAS/DTM there but you must have a stereo block from same set. In this exact case it might work as you have stereo pair for SGM and feeding that to Terrain Editor might work.

 

So my request is that can we drop out stereo pair requirement from Terrain Editor so that all those editing tools would be available just for pure LAS/DTM files?

Valued Contributor
Posts: 517
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

[ Edited ]

Thank you Angelamanchester

But those point clouds in the training video you post are LIDAR classified point clouds.

My point cloud is not classified

 

regards

Frequent Contributor
Posts: 153
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

Point cloud classification is simple run while running SGM, just choose that tick box. There is also a classifier tool in Terrain section of Imagine but that most likely does not work with SGM data as in SGM there is just single return.

Valued Contributor
Posts: 517
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

Thank you Timo!

In IMAGINE 16.1 I do not see any classification tick box in SGM wizard.

In the Point Cloud toolbar the Classify tool is grey when I load my SGM point cloud.

I'm doing a test with the classification tool in  Surface Prep Tool.

 

Any advice is welcome

 

regards

Giuseppe

Frequent Contributor
Posts: 153
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

It could be that classification tick is just in eATE....some of these Stereo to point cloud toos for sure had that. I have some doubts that your result in Terrain Prep or Point Cloud Toolbar as your point cloud is a special kind of point cloud and I doubt those tools are designed for this kind of data.

Regular Contributor
Posts: 214
Registered: ‎11-16-2015

Re: SGM Point Cloud EDITING

Funnily enough I've been looking at exactly the same issue with WV3 data this week. I've been getting similar errors over buildings - and in fact just lots of spikes / holes in general - that need cleaning up. 

 

Classification isn't going to help so far as I can see - and classification isn't available in either SGM process. What I really need within IMAGINE to sort this out is the sort of noise removal functionality that is available in LASTools. 

 

However, it's strange that classification isn't availabel for you from the point cloud tab. I've no idea why that should be the case. Again, though, LASTools has more sophisticated routines for point cloud classification. I've issues with the IMAGINE routine as it apears that using Greeness degrades the result rather than helping and there's no way to use NIR successfully in the process.

 

For me it seems that if you want to automate a decent point cloud creation flow line from stereo high res satellite data, you will need to use LASTools as the functionality just isn't there/good enough within the IMAGINE toolset. It's just a shame the LASTools isn't yet integrated into v16.1.

Valued Contributor
Posts: 517
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

Hello everybody,

I installed LAS Tools for ERDAS IMAGINE 15.1 on a virtual machine and I'm tryng to cleaning up my point cloud.

I tried the Remove Noise tool, with default value, but the noise is still there.

Any suggestions on the workflow I can use?

thank you

Valued Contributor
Posts: 517
Registered: ‎10-27-2015

Re: SGM Point Cloud EDITING

I pushed, for error, on the "accept as solution" button

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